This document describes an electric meter circuit that provides an electrically suppressed zero. It achieves this by including a non-linear conductive device, such as a diode, in series with a galvanometer. The non-linear device has a very high resistance for low voltages/currents, resulting in minimal galvanometer deflection. At higher voltages/currents above a threshold like the diode's avalanche point, the device has a nearly constant low resistance, causing the galvanometer to respond nearly linearly to changes in voltage/current. This allows the meter to accurately measure voltages above the suppressed zero point while ignoring lower voltages. The non-linear device is compact and stable, avoiding issues of prior suppressed zero methods.
This document describes an electrical circuit that allows a load to be connected to a voltage source without drawing substantial current from that source. It does this through the addition of an "isolator circuit" parallel to the source-load connection. The isolator circuit generates a compensating current equal to what would be drawn from the voltage source, and feeds that current to the load instead. Several examples of implementations for both alternating current and direct current circuits are provided.
Three phase inverter - 180 and 120 Degree Mode of ConductionMalarselvamV
The document describes the operation of a 3-phase inverter that generates 3-phase AC voltage from a DC source using switches in both 180 degree and 120 degree conduction modes. In the 180 degree mode, each switch is closed for 180 degrees before the next switch closes. In the 120 degree mode, each switch is closed for 120 degrees. Tables show the switch states and resulting phase and line voltages for each 60 degree period. While the output waveforms are not pure sine waves, they approximate the desired 3-phase voltages. The inverter circuit provides a simple example for understanding 3-phase inverter operation.
This lab report summarizes experiments conducted to study Ohm's Law and circuit behavior. The experiments involved measuring currents and voltages in circuits with single and dual power supplies connected to various resistor configurations. The results showed that resistance decreases in parallel circuits as predicted by Ohm's Law. Kirchhoff's Laws and the conservation of energy were also verified. Overall, the experimental findings supported the theoretical understanding of how voltage, current and resistance relate in electrical circuits.
This document provides instructions for testing the short-circuit impedance and load loss of transformers. The short-circuit voltage and loss show the transformer's performance and are important specifications. To measure: the HV windings are supplied while the LV windings are short-circuited, applying a current close to the rated current. Voltage, current and losses are measured in each phase. Losses are corrected to a reference temperature and separated into DC and AC components. Measurements are made at rated, maximum and minimum ranges.
This document discusses bridge circuits and their use in instrumentation and measurements. It describes how bridge circuits like the Wheatstone bridge use a null detection or null balancing principle to measure unknown components. The key advantages of bridge circuits are their high accuracy due to comparison-based measurements and independence from input voltage or source impedance. The document outlines various types of DC and AC bridges, providing examples like the Wheatstone, Kelvin, and Maxwell bridges. It also discusses bridge measurement techniques, sources of error, applications, and the use of bridges in control systems.
This document describes a three phase inverter that converts DC voltage to AC voltage. There are two main modes of conduction for a three phase inverter - 180 degree conduction and 120 degree conduction. 180 degree conduction involves three switches being on at a time, while 120 degree conduction only has two switches on at a time. The document provides circuit diagrams and equations to calculate the output voltages under each conduction mode. Waveforms are also shown to illustrate the phase and line voltages.
Knee point & primary current injection testBasudev patra
This document describes test procedures for determining the knee point voltage and verifying the current transformation ratio of a current transformer (CT). The knee point test involves gradually increasing the voltage source connected to the primary winding while the other windings are open, and recording the voltage and current readings. The primary current injection test involves injecting current into the primary winding with the secondary winding shorted, and recording the actual and calculated current ratios. Both tests are intended to check specifications listed on the CT nameplate.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document describes an electrical circuit that allows a load to be connected to a voltage source without drawing substantial current from that source. It does this through the addition of an "isolator circuit" parallel to the source-load connection. The isolator circuit generates a compensating current equal to what would be drawn from the voltage source, and feeds that current to the load instead. Several examples of implementations for both alternating current and direct current circuits are provided.
Three phase inverter - 180 and 120 Degree Mode of ConductionMalarselvamV
The document describes the operation of a 3-phase inverter that generates 3-phase AC voltage from a DC source using switches in both 180 degree and 120 degree conduction modes. In the 180 degree mode, each switch is closed for 180 degrees before the next switch closes. In the 120 degree mode, each switch is closed for 120 degrees. Tables show the switch states and resulting phase and line voltages for each 60 degree period. While the output waveforms are not pure sine waves, they approximate the desired 3-phase voltages. The inverter circuit provides a simple example for understanding 3-phase inverter operation.
This lab report summarizes experiments conducted to study Ohm's Law and circuit behavior. The experiments involved measuring currents and voltages in circuits with single and dual power supplies connected to various resistor configurations. The results showed that resistance decreases in parallel circuits as predicted by Ohm's Law. Kirchhoff's Laws and the conservation of energy were also verified. Overall, the experimental findings supported the theoretical understanding of how voltage, current and resistance relate in electrical circuits.
This document provides instructions for testing the short-circuit impedance and load loss of transformers. The short-circuit voltage and loss show the transformer's performance and are important specifications. To measure: the HV windings are supplied while the LV windings are short-circuited, applying a current close to the rated current. Voltage, current and losses are measured in each phase. Losses are corrected to a reference temperature and separated into DC and AC components. Measurements are made at rated, maximum and minimum ranges.
This document discusses bridge circuits and their use in instrumentation and measurements. It describes how bridge circuits like the Wheatstone bridge use a null detection or null balancing principle to measure unknown components. The key advantages of bridge circuits are their high accuracy due to comparison-based measurements and independence from input voltage or source impedance. The document outlines various types of DC and AC bridges, providing examples like the Wheatstone, Kelvin, and Maxwell bridges. It also discusses bridge measurement techniques, sources of error, applications, and the use of bridges in control systems.
This document describes a three phase inverter that converts DC voltage to AC voltage. There are two main modes of conduction for a three phase inverter - 180 degree conduction and 120 degree conduction. 180 degree conduction involves three switches being on at a time, while 120 degree conduction only has two switches on at a time. The document provides circuit diagrams and equations to calculate the output voltages under each conduction mode. Waveforms are also shown to illustrate the phase and line voltages.
Knee point & primary current injection testBasudev patra
This document describes test procedures for determining the knee point voltage and verifying the current transformation ratio of a current transformer (CT). The knee point test involves gradually increasing the voltage source connected to the primary winding while the other windings are open, and recording the voltage and current readings. The primary current injection test involves injecting current into the primary winding with the secondary winding shorted, and recording the actual and calculated current ratios. Both tests are intended to check specifications listed on the CT nameplate.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The document discusses three phase voltage source inverters. It begins by introducing inverters and their use in converting DC to AC power. It then classifies inverters as voltage source or current source. The main topic is the three phase voltage source inverter, which converts DC to three phase AC power using six switches in three arms delayed by 120 degrees. The inverter can operate in 180 degree or 120 degree conduction modes, which determine the output phase and line voltages. Applications of three phase inverters include DC power utilization, UPS, induction heating, variable frequency drives, and electric vehicle drives.
The Wheatstone bridge is a circuit invented in 1833 by Samuel Hunter Christie to measure an unknown electrical resistance. It uses a galvanometer to monitor a balanced state where no current flows through the galvanometer (ig=0). By adjusting variable resistors to reach this balanced state, the mathematical ratio of the arms can be used to calculate the fourth unknown resistance. The Wheatstone bridge found many applications in measuring strain, locating breaks in power lines, and indirectly measuring other variables that impact electrical resistance, such as temperature, force, and pressure.
Knee-Point Voltage Determination for Current Transformer Functional Identific...IJERD Editor
An experiment was conducted to determine the knee-point voltage of 4 current transformers (CTs) intended for use in a substation power transformer protection system. Open-circuit tests were performed on the CTs to collect voltage and current readings, from which magnetization curves were generated using MATLAB. The magnetization curves revealed that all 4 CTs had a knee-point voltage of 1000V, indicating they were protection CTs rather than metering CTs, which typically have a lower knee-point voltage of 60-120V. Having a knee-point voltage in the specified range of 200-1900V confirmed the CTs were suitable for the protection requirements of the power transformer.
The document discusses various types of bridges used for instrumentation and measurement, including the Anderson bridge, Hay's bridge, Schering bridge, and Wien bridge. It also covers digital to analog conversion techniques such as binary weighted and R-2R ladder DACs. Key aspects like resolution, accuracy, monotonicity, conversion time, and stability are discussed as performance parameters for DACs.
This practicum report describes experiments using a Wheatstone bridge circuit to determine unknown resistor values. The objectives are to determine resistor values indirectly and more accurately compared to using Ohm's law alone. Two experiments are conducted to find unknown resistor values paired with resistors of known values. The first experiment estimates the unknown resistor at 85.71 ohms and the second at 15.67 ohms. Some error is observed in the measurements. The report concludes by discussing sources of error and reviewing the application of Wheatstone bridge principles.
The Wheatstone Bridge was invented in 1833 to measure electrical resistance using a ratio of three known resistors and one unknown resistor. By balancing the bridge, the unknown resistance can be calculated mathematically. It is widely used to this day to monitor sensors and locate breaks in power lines due to its simple, inexpensive, and accurate design.
This document discusses single phase inverters. It describes:
1. Single pulse width modulation, which controls output voltage by varying the width of pulses in each half cycle compared to a triangular carrier signal.
2. A single phase half bridge inverter, which uses two switches and capacitors to divide the DC source voltage. Feedback diodes provide current continuity for inductive loads.
3. A full bridge single phase inverter, which uses four thyristors controlled such that only one pair conducts at a time to produce an AC output voltage from the DC source. Feedback diodes allow current to flow when thyristors turn off.
The presentation explain Wheatstone bride and its application for determination of current , resistances in network .The presentation also explain principle ,construction and working also application of meter bridge . it is useful foe students who are studying physics in senior secondary level in Indian school
This document provides information about transformer tests conducted at BEST Balıkesir Transformer Factory laboratories. It describes routine tests like winding resistance measurement, voltage ratio measurement and phase checking, as well as type tests and special tests. The routine tests section explains test procedures and equipment for various tests done on all transformers produced. These include impedance measurement, no-load loss tests, and tap changer tests. Type and special tests involve temperature rise testing, lightning impulse testing, and other advanced analyses. Laboratory equipment for performing over a dozen transformer tests is also listed.
The inverse quantity is electrical conductance, and is the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with the notion of mechanical friction. The SI unit of electrical resistance is the ohm (Ω), while electrical conductance is measured in siemens (S).
The document describes several embodiments of a spark-cutting apparatus that uses capacitors and circuitry to eliminate direct current flow from a power source to a spark gap. This prevents excessive electrode erosion. The apparatus uses two capacitors connected in series to block direct current flow. Alternate embodiments use an alternating current source to charge the capacitors and include additional components like inductors, transformers, and switches to control the timing and frequency of spark discharges.
This document discusses sinusoidal waves and their characteristics. It defines key terms like period, frequency, amplitude, phase angle, and explains how to calculate these values. Period is the time for one full cycle, frequency is the number of cycles per second. Amplitude refers to the maximum voltage or current values. Phase angle describes the shift between two sinusoidal waves with the same frequency. A lagging signal has a negative phase angle compared to the reference, while a leading signal has a positive phase angle.
This document discusses 180 degree conduction mode for a 3-phase inverter. It contains the following information:
1) In 180 degree conduction mode, each switch conducts for a period of 180 degrees with switches triggered in a sequence with an interval of 60 degrees. At any time, three switches (one from each leg) conduct.
2) The complete cycle is divided into six modes with the switching sequence and conducting devices specified for each interval.
3) Equations are provided for the operation and output voltages of each interval along with waveform diagrams showing the phase voltages and line-to-line voltages.
4) Fourier analysis is used to derive expressions for the fundamental and higher order harmonic components of
This document describes the construction and application of a Wheatstone bridge circuit. It begins by introducing Wheatstone bridges and their inventor. It then discusses the key components of a Wheatstone bridge, including four resistors where one has an unknown value. The working principle is explained, where balancing the resistor ratios results in no current through the galvanometer. Example circuits are provided. Applications include measuring light, pressure, strain and more. Limitations include inaccuracies under unbalanced conditions and limited resistance ranges.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
A.C. bridges are circuits used to measure unknown resistances, capacitances, inductances, frequencies, and mutual inductances. Some common bridges include the Wheatstone bridge for measuring resistance using direct current, Maxwell's bridges for measuring inductance using alternating current, and the De Sauty, Schering, Wien series, and Wien parallel bridges for measuring capacitance using various balanced circuit configurations. Each bridge uses a balanced circuit equation to relate known components to unknown values.
The Wheatstone bridge is a device used to measure unknown electrical resistance. It consists of four resistors arranged in a diamond shape with two resistors of known value, one resistor of unknown value, and one variable resistor. By adjusting the variable resistor to balance the bridge circuit and produce a null reading on the galvanometer, the ratio of the two legs is equal to the ratio of the unknown resistor to the variable resistor, allowing the unknown value to be determined. The Wheatstone bridge works on the principle of null deflection and accurate resistance measurement.
EMI Unit 5 Bridges and Measurement of Physical ParametersGVNSK Sravya
This document discusses bridges and measurement of physical parameters. It describes various types of bridges - Wheatstone bridge, Kelvin bridge, and Maxwell bridge. It explains their working principles, advantages, limitations and provides examples. It also discusses measurement of different physical parameters like flow, displacement, liquid level, temperature, humidity, velocity, force, pressure, vacuum and data acquisition systems.
This document discusses alternating current (AC) circuits containing resistors, capacitors, and inductors. It begins by introducing AC circuits and defining the sinusoidal output of an AC generator. It then examines each circuit element individually:
- Resistors allow current proportional to voltage in an AC circuit, similar to DC circuits. RMS values are used to quantify AC power dissipation in resistors.
- Capacitors oppose changes in voltage by drawing/supplying current, causing the voltage to lag the current by 90 degrees. Capacitive reactance describes this opposition.
- Inductors oppose changes in current by inducing a back EMF, causing the current to lag the voltage by 90 degrees. Inductive
this contant is physics related.Here AC current explain on the purpose of presentation with some equation and circuit diagram.i thaink it wiil be very effective for the students.
This document describes an invention for an apparatus used in radio navigation systems. The apparatus indicates the position of a vehicle on a chart based on received radio signals. It includes a storage device that can maintain the rate of movement of an index on the chart over short periods where the radio signals may be interrupted. This prevents errors in the index position when signals resume. The storage device works by storing the rate and direction of index movement steps during the previous period, and can control the index accordingly during a signal failure. It utilizes a rotating carrier with operating elements that can be switched between sides of a guide, producing pulses as they pass contacts on one side to mimic the stored rate of movement.
This document describes a 1957 patent for an oscillating column combustion apparatus. The apparatus has a combustion chamber and pulsating tube that form an acoustic resonator. It is an improvement over prior designs by introducing the combustion mixture tangentially into the cylindrical combustion chamber through a mixing tube. This causes the mixture to circulate and thermally prepare along the hot chamber walls before igniting, overcoming issues with deposits clogging inlet throats in previous models. The pulsating tube can be arranged coaxially to induce better vortexing for ignition.
The document discusses three phase voltage source inverters. It begins by introducing inverters and their use in converting DC to AC power. It then classifies inverters as voltage source or current source. The main topic is the three phase voltage source inverter, which converts DC to three phase AC power using six switches in three arms delayed by 120 degrees. The inverter can operate in 180 degree or 120 degree conduction modes, which determine the output phase and line voltages. Applications of three phase inverters include DC power utilization, UPS, induction heating, variable frequency drives, and electric vehicle drives.
The Wheatstone bridge is a circuit invented in 1833 by Samuel Hunter Christie to measure an unknown electrical resistance. It uses a galvanometer to monitor a balanced state where no current flows through the galvanometer (ig=0). By adjusting variable resistors to reach this balanced state, the mathematical ratio of the arms can be used to calculate the fourth unknown resistance. The Wheatstone bridge found many applications in measuring strain, locating breaks in power lines, and indirectly measuring other variables that impact electrical resistance, such as temperature, force, and pressure.
Knee-Point Voltage Determination for Current Transformer Functional Identific...IJERD Editor
An experiment was conducted to determine the knee-point voltage of 4 current transformers (CTs) intended for use in a substation power transformer protection system. Open-circuit tests were performed on the CTs to collect voltage and current readings, from which magnetization curves were generated using MATLAB. The magnetization curves revealed that all 4 CTs had a knee-point voltage of 1000V, indicating they were protection CTs rather than metering CTs, which typically have a lower knee-point voltage of 60-120V. Having a knee-point voltage in the specified range of 200-1900V confirmed the CTs were suitable for the protection requirements of the power transformer.
The document discusses various types of bridges used for instrumentation and measurement, including the Anderson bridge, Hay's bridge, Schering bridge, and Wien bridge. It also covers digital to analog conversion techniques such as binary weighted and R-2R ladder DACs. Key aspects like resolution, accuracy, monotonicity, conversion time, and stability are discussed as performance parameters for DACs.
This practicum report describes experiments using a Wheatstone bridge circuit to determine unknown resistor values. The objectives are to determine resistor values indirectly and more accurately compared to using Ohm's law alone. Two experiments are conducted to find unknown resistor values paired with resistors of known values. The first experiment estimates the unknown resistor at 85.71 ohms and the second at 15.67 ohms. Some error is observed in the measurements. The report concludes by discussing sources of error and reviewing the application of Wheatstone bridge principles.
The Wheatstone Bridge was invented in 1833 to measure electrical resistance using a ratio of three known resistors and one unknown resistor. By balancing the bridge, the unknown resistance can be calculated mathematically. It is widely used to this day to monitor sensors and locate breaks in power lines due to its simple, inexpensive, and accurate design.
This document discusses single phase inverters. It describes:
1. Single pulse width modulation, which controls output voltage by varying the width of pulses in each half cycle compared to a triangular carrier signal.
2. A single phase half bridge inverter, which uses two switches and capacitors to divide the DC source voltage. Feedback diodes provide current continuity for inductive loads.
3. A full bridge single phase inverter, which uses four thyristors controlled such that only one pair conducts at a time to produce an AC output voltage from the DC source. Feedback diodes allow current to flow when thyristors turn off.
The presentation explain Wheatstone bride and its application for determination of current , resistances in network .The presentation also explain principle ,construction and working also application of meter bridge . it is useful foe students who are studying physics in senior secondary level in Indian school
This document provides information about transformer tests conducted at BEST Balıkesir Transformer Factory laboratories. It describes routine tests like winding resistance measurement, voltage ratio measurement and phase checking, as well as type tests and special tests. The routine tests section explains test procedures and equipment for various tests done on all transformers produced. These include impedance measurement, no-load loss tests, and tap changer tests. Type and special tests involve temperature rise testing, lightning impulse testing, and other advanced analyses. Laboratory equipment for performing over a dozen transformer tests is also listed.
The inverse quantity is electrical conductance, and is the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with the notion of mechanical friction. The SI unit of electrical resistance is the ohm (Ω), while electrical conductance is measured in siemens (S).
The document describes several embodiments of a spark-cutting apparatus that uses capacitors and circuitry to eliminate direct current flow from a power source to a spark gap. This prevents excessive electrode erosion. The apparatus uses two capacitors connected in series to block direct current flow. Alternate embodiments use an alternating current source to charge the capacitors and include additional components like inductors, transformers, and switches to control the timing and frequency of spark discharges.
This document discusses sinusoidal waves and their characteristics. It defines key terms like period, frequency, amplitude, phase angle, and explains how to calculate these values. Period is the time for one full cycle, frequency is the number of cycles per second. Amplitude refers to the maximum voltage or current values. Phase angle describes the shift between two sinusoidal waves with the same frequency. A lagging signal has a negative phase angle compared to the reference, while a leading signal has a positive phase angle.
This document discusses 180 degree conduction mode for a 3-phase inverter. It contains the following information:
1) In 180 degree conduction mode, each switch conducts for a period of 180 degrees with switches triggered in a sequence with an interval of 60 degrees. At any time, three switches (one from each leg) conduct.
2) The complete cycle is divided into six modes with the switching sequence and conducting devices specified for each interval.
3) Equations are provided for the operation and output voltages of each interval along with waveform diagrams showing the phase voltages and line-to-line voltages.
4) Fourier analysis is used to derive expressions for the fundamental and higher order harmonic components of
This document describes the construction and application of a Wheatstone bridge circuit. It begins by introducing Wheatstone bridges and their inventor. It then discusses the key components of a Wheatstone bridge, including four resistors where one has an unknown value. The working principle is explained, where balancing the resistor ratios results in no current through the galvanometer. Example circuits are provided. Applications include measuring light, pressure, strain and more. Limitations include inaccuracies under unbalanced conditions and limited resistance ranges.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
A.C. bridges are circuits used to measure unknown resistances, capacitances, inductances, frequencies, and mutual inductances. Some common bridges include the Wheatstone bridge for measuring resistance using direct current, Maxwell's bridges for measuring inductance using alternating current, and the De Sauty, Schering, Wien series, and Wien parallel bridges for measuring capacitance using various balanced circuit configurations. Each bridge uses a balanced circuit equation to relate known components to unknown values.
The Wheatstone bridge is a device used to measure unknown electrical resistance. It consists of four resistors arranged in a diamond shape with two resistors of known value, one resistor of unknown value, and one variable resistor. By adjusting the variable resistor to balance the bridge circuit and produce a null reading on the galvanometer, the ratio of the two legs is equal to the ratio of the unknown resistor to the variable resistor, allowing the unknown value to be determined. The Wheatstone bridge works on the principle of null deflection and accurate resistance measurement.
EMI Unit 5 Bridges and Measurement of Physical ParametersGVNSK Sravya
This document discusses bridges and measurement of physical parameters. It describes various types of bridges - Wheatstone bridge, Kelvin bridge, and Maxwell bridge. It explains their working principles, advantages, limitations and provides examples. It also discusses measurement of different physical parameters like flow, displacement, liquid level, temperature, humidity, velocity, force, pressure, vacuum and data acquisition systems.
This document discusses alternating current (AC) circuits containing resistors, capacitors, and inductors. It begins by introducing AC circuits and defining the sinusoidal output of an AC generator. It then examines each circuit element individually:
- Resistors allow current proportional to voltage in an AC circuit, similar to DC circuits. RMS values are used to quantify AC power dissipation in resistors.
- Capacitors oppose changes in voltage by drawing/supplying current, causing the voltage to lag the current by 90 degrees. Capacitive reactance describes this opposition.
- Inductors oppose changes in current by inducing a back EMF, causing the current to lag the voltage by 90 degrees. Inductive
this contant is physics related.Here AC current explain on the purpose of presentation with some equation and circuit diagram.i thaink it wiil be very effective for the students.
This document describes an invention for an apparatus used in radio navigation systems. The apparatus indicates the position of a vehicle on a chart based on received radio signals. It includes a storage device that can maintain the rate of movement of an index on the chart over short periods where the radio signals may be interrupted. This prevents errors in the index position when signals resume. The storage device works by storing the rate and direction of index movement steps during the previous period, and can control the index accordingly during a signal failure. It utilizes a rotating carrier with operating elements that can be switched between sides of a guide, producing pulses as they pass contacts on one side to mimic the stored rate of movement.
This document describes a 1957 patent for an oscillating column combustion apparatus. The apparatus has a combustion chamber and pulsating tube that form an acoustic resonator. It is an improvement over prior designs by introducing the combustion mixture tangentially into the cylindrical combustion chamber through a mixing tube. This causes the mixture to circulate and thermally prepare along the hot chamber walls before igniting, overcoming issues with deposits clogging inlet throats in previous models. The pulsating tube can be arranged coaxially to induce better vortexing for ignition.
The document describes British patent GB780070 (A) from 1957 regarding improvements to vehicle couplings. It includes a detailed description of a coupling member that connects a trailer to a towing vehicle. The coupling member features a brake actuating element to engage the trailer's brakes during overrun, as well as a manually operable brake applying member. The invention aims to reduce maintenance needs and improve operation by enclosing retention means for the manually operable brake within an inverted box-like housing.
This patent document describes a self-gripping tool for turning socket head fasteners such as Allen screws. The tool consists of two elongated wire members held together that form a hexagonal shape to fit inside the socket. The wire members are slightly separated and compress inward when inserted into the socket, exerting outward pressure to frictionally grip the interior walls. This provides an inexpensive and easy to use tool for securely holding socket head fasteners during installation.
This document describes a patent from 1957 for an improved lifting jack. The lifting jack has an inner and outer tubular element, with a hooked lifting element carried by the outer tube. Typically the hook was welded to the outer tube, but this could cause fractures. The new design forms a recess in the outer tube and the hook has a clamping means that seats in the recess. This provides a stronger connection that is less likely to fracture during use.
This document describes a 1957 patent for an improved galvanic copper plating method. It involves simultaneously spraying an aqueous copper sulfate solution containing phosphoric acid and an aqueous suspension of a metal dust, such as zinc, iron, cadmium, or nickel, onto a metal surface. The metal dust reacts with the copper sulfate to deposit a layer of metallic copper that is hardened as it forms, creating a more protective and durable copper coating than previous methods. The invention was meant to provide a simple, economical way to deposit hardened copper galvanically without special equipment.
The document describes a process for manufacturing sheet materials composed of adhesively bonded fibers. It involves drawing fibers from a carding machine and conveying them to a lapping machine, which deposits overlapping layers on a conveyor belt. Bonding agents are introduced between the layers by jets that inject a small cloud of agents into the air between falling layers, allowing even distribution. The layered material is then consolidated by pressure and dried to form the finished product.
1. The document describes improvements to a collapsible metal box or container with hinged sides, lid, and bottom that allows it to fold flat for storage.
2. Adjacent sides of the box are hinged together using alternating tubular members that receive hinge pins. The lid and bottom are also hinged to opposite sides using the same tubular member system.
3. When collapsed for storage or transport, the sides, lid, and bottom all lie in parallel planes, occupying less space than when erected. The boxes can be stacked efficiently in the folded flat configuration.
This document is a patent application for improvements to sheet metal working machines. Specifically, it describes a machine that uses a wedge-shaped member moved transversely to lift a movable die. Balls or rollers between the wedge and movable die/frame allow transverse movement while maintaining uniform pressure across the die. The preferred embodiment uses a hydraulic cylinder to operate the wedge and ensure even lifting of the die for consistent metal bending results.
This document describes an improved plastic shortening composition and method of making it. The shortening comprises a minor proportion of a hard stock that is highly hydrogenated to an iodine value below 10 and contains at least 90% C18 fatty acids. The major proportion is a partially hydrogenated base stock with an iodine value between 80-95 and containing at least 87% C18 fatty acids. Prior shortenings were unstable at high storage temperatures, but the improved composition maintains plasticity when stored at around 90°F for extended periods due to the crystalline fats being predominantly in the beta phase.
This document describes a patent for a synchronizing device for changing gears in vehicles. The device aims to overcome issues where significant force is needed to shift gears when the vehicle is stationary. It does this through a supporting ring that increases synchronization force in one direction of rotation, but is held ineffective by stops in the other direction. This allows easy gear shifting when stationary but maintains sufficient synchronization force for other gear changes.
This document describes improvements to telephone instruments, specifically addressing issues that can arise with standing microphones. It details circuitry designs that prevent unintentional operation of cradle switches from disturbing impulse transmission during dialing. The designs ensure the impulse circuit remains uninterrupted even if the cradle switch is activated by accident. Diagrams show how contacts in the circuits are arranged to isolate the impulse transmission from cradle switch operation.
This document describes a web tension control mechanism with the following key elements and functions:
1) It includes a carriage carrying a pair of parallel web guiding rollers that can move left and right. A spring biases the carriage to the left while a variable speed drive biases it to the right to maintain tension.
2) As the carriage moves, it adjusts the effective diameter of a V-belt pulley in the variable speed drive to instantly increase or decrease the roller speeds and maintain constant web tension.
3) The mechanism precisely regulates web tension without introducing slack and maintains a uniform web length between points, allowing accurate register between successive printing operations.
This document is a patent application for an adjustable mirror supported on a floor stand. The mirror stand has two parallel tubular members that can be adjusted longitudinally to change the height of the mirror. The mirror frame can rotate horizontally and vertically, and has both a flat and concave mirror. It also has an adjustable tray below the mirror for holding cosmetics. The stand can be easily disassembled for transport and reassembled.
The document describes a temperature controller or overheating safeguard device for electrical hot plates. It uses a ferromagnetic armature fixed to the hot plate that loses its magnetism at a specific Curie point temperature. A permanent magnet on a lever is also mounted on the hot plate and interacts with the armature to open or close an electric switch controlling current to the hot plate. When the temperature rises above the Curie point, the armature loses magnetism, causing the magnet to move away and open the switch to cut off current.
This document describes a patent for improvements to electronic time-base generators. It includes a circuit diagram and description of a generator that uses negative feedback to linearize the output waveform by differentiating the voltage across a scanning coil and using it to control a feedback valve. This counteracts nonlinearity from exponential charging/discharging of capacitors. It allows the scanning speed and sweep magnitude to be varied by controlling the bias on the feedback valve.
1. The document describes improvements to liquid pipelines, particularly those used to transfer hydrocarbon fuels between reservoirs like aviation fuel.
2. It aims to provide an automatic mechanical safeguard to stop the flow of oil in the pipeline as soon as water is detected using a filter pack that expands when it absorbs water.
3. The filter pack is located in an auxiliary channel between two points in the main liquid flow channel, and means are provided to indicate the presence of water and/or automatically stop liquid flow through the pipeline when the filter pack expands.
This document describes a press member for garment pressing machines. It consists of gritty particles secured to a rigid backing member. The gritty particles are resistant to crushing, heat and moisture and have sharp edges. This creates an irregularly roughened pressing surface that eliminates wrinkles and creates sharp creases without imparting shine or moire patterns to fabrics. The gritty particles form a layer between the fabric and backing member to prevent any patterns on the backing from being transferred.
The document discusses errors in electrodynamometer type wattmeters and their compensation. It describes 10 types of errors including errors due to pressure coil inductance and capacitance, mutual inductance effects, connections, eddy currents, stray magnetic fields, and vibration. Methods to compensate for errors include using a capacitor across the pressure coil, designing coils with zero mutual inductance, and connecting coils to minimize power losses. The document also lists advantages like measuring AC and DC power, and disadvantages such as errors at low power factors.
This document describes British patent GB780024 (A) for improvements in weighing apparatus. The weighing apparatus uses a weight-carrying platform mounted on a conducting coil located in a magnetic field. Current is passed through the coil to support the platform in a floating position. When a weight is placed on the platform, the current through the coil is increased to restore the position, and the current variations are indicated to show the weight. The apparatus provides a fast response time and can indicate weight as a voltage, making it suitable for automatic control applications.
This document describes improvements to weighing apparatus. It consists of a weight-carrying platform mounted on a conducting coil located in a magnetic field. When weight is placed on the platform, the coil moves and current through the coil is increased to restore its position. Variations in current are then indicated to show weight. The apparatus provides a fast response time and can indicate weight as a voltage or pulses, making it suitable for automation and control applications. It is described as having advantages over normal scales such as faster weighing times important for production line applications.
This document describes British patent GB780024 (A) for improvements in weighing apparatus. The weighing apparatus uses a weight-carrying platform mounted on a conducting coil located in a magnetic field. Current is passed through the coil to support the platform in a floating position. When a weight is placed on the platform, the current through the coil is increased to restore the position, and the current variations are indicated to show the weight. The apparatus provides a fast response time and can indicate weight as a voltage, making it suitable for automatic control applications.
This document describes British patent GB780024 (A) for improvements in weighing apparatus. The weighing apparatus uses a weight-carrying platform mounted on a conducting coil located in a magnetic field. Current is passed through the coil to support the platform in a floating position. When weight is placed on the platform, the current through the coil is increased to restore the position. The current variations are then used to indicate the measured weight. The apparatus provides a fast response time and can indicate weight as a voltage, making it suitable for automatic control applications.
The document discusses potentiometers and their use in measuring electrical quantities. It describes:
1) The construction and working of DC potentiometers including slide wire and Crompton types, and their applications in measuring resistance, calibrating voltmeters and ammeters.
2) The construction of AC potentiometers including in-phase and quadrature types, and their standardization process.
3) How potentiometers can be used to accurately measure small voltages and currents by balancing the unknown quantity against a known standard voltage.
The document provides details about three experiments conducted using instrumentation and control systems lab equipment:
1. The first experiment investigates strain gauges and how metal foil gauges can be used to measure strain. A linear relationship was observed between position and output voltage.
2. The second experiment uses a Wheatstone bridge circuit to determine the value of an unknown resistor. The measured value matched closely with the theoretical value.
3. The third experiment studies a linear variable differential transformer (LVDT) and how it can convert mechanical displacement into an electrical output signal. Graphs of AC and DC output versus core position showed the expected linear relationship.
The document describes the components and operation of a multimeter. It has a moving coil galvanometer with a coil that rotates in a magnetic field. To measure high voltages, a high resistance is connected in series. AC voltage is rectified before reaching the galvanometer. A shunt resistance converts it to an ammeter. Resistance is measured using an internal battery and adjustable resistance. Electrodynamic instruments have high accuracy for AC and DC measurements. They have fixed and moving coils and use springs or weights for control and air damping. Wattmeters use the moving coil to indicate voltage and fixed coils in series with the load to indicate current. Errors can occur due to coil inductance/capacitance and stray magnetic fields. Three
This document describes a patent for improvements to machines that machine conducting materials using electric discharges. It discusses challenges with existing machines, such as frequent short circuits that can damage the machined surface. The invention aims to reduce the frequency of short circuits and eliminate their harmful effects by using an induction coil in the charging circuit. The induction coil is tuned so that its half oscillation period matches the period between discharges, allowing discharges to occur for near-zero charging current and avoiding problems from short circuits.
This document describes a patent for improvements to machines that machine conducting materials using electric discharges. It discusses issues with prior art machines, such as frequent short circuits that can damage the machined surface. The invention aims to reduce the frequency of short circuits and eliminate their harmful effects by using an induction coil in the charging circuit. The induction coil is tuned so that its half oscillation period matches the period between discharges, allowing discharges to occur at near-zero charging current to avoid short circuit issues.
A potentiometer is an instrument used to measure voltage by comparing an unknown voltage to a known reference voltage. It works by balancing the voltages such that no current flows through the circuit, making the measurement independent of source resistance. An AC potentiometer is similar but can measure both magnitude and phase angle of an unknown AC voltage by balancing against a known AC reference. It requires non-inductive components and a pure sine wave source to avoid errors in measurement. Potentiometers are used to calibrate voltmeters, ammeters, wattmeters and to directly measure voltages, currents, resistances, and powers in circuits.
The document discusses various methods for measuring electrical quantities like voltage, current, resistance, inductance and capacitance. It describes potentiometer techniques for measuring voltage and current using a known resistance. It also explains different types of bridges - DC Wheatstone bridge, AC impedance bridge, Maxwell bridge, Schering bridge and Hay bridge - that provide accurate measurement of resistance, inductance and capacitance using null detection. The working and balancing equations of these bridges are provided. The document also discusses Wien bridge oscillator and amplitude stabilization using a positive temperature coefficient thermistor.
The document summarizes Hewlett-Packard's new 456A AC Current Probe, which can measure AC currents from 25 kHz to 20 MHz over an amplitude range from less than 0.5 mA to 1 A RMS. The probe clips onto conductors non-invasively to measure currents without loading circuits. It has a fast 20 ms rise time and low 0.05 uH/50 mΩ loading. The probe is compatible with several HP oscilloscopes and voltmeters to display current waveforms and measurements. It enables convenient measurement of currents in applications that were previously difficult, such as in ground wires and solid-state circuits.
This document describes the development of a circuit for measuring high voltage corona pulses in a coaxial cylindrical geometry. Previous circuits suffered from stray capacitance and impedance mismatches distorting the measured waveforms. The new circuit presented terminates a transmission line connecting the corona electrode directly within the cylinder. This provides a reflection-free path for the induced currents, enabling faithful measurement of corona pulses as fast as 5 nanoseconds for negative corona. While an improvement, the measuring oscilloscope's 85 MHz bandwidth still limited observation of negative corona pulses believed to occur faster than 5 ns.
This experiment involves drawing the V and inverted V curves of a 3-phase synchronous motor under no-load and load conditions. The V curve shows the relationship between field current (I) and terminal voltage (V) of the motor. The inverted V curve shows the relationship between power factor and field current. Under normal excitation, the power factor is unity. Under-excitation results in lagging power factor while over-excitation results in leading power factor. The curves are drawn to determine the operating characteristics of the synchronous motor at different excitation levels.
All About Electrical Connections of Force TransducersTacuna Systems
The document discusses the electrical connections of force transducers, specifically strain gauge load cells. It explains that strain gauge load cells use a Wheatstone bridge circuit to convert variations in electrical resistance caused by applied force into proportional voltage signals. A four-wire system connects power and output signals, while a six-wire system adds sense wires to compensate for voltage drops in long connecting cables. Key electrical specifications for load cells include excitation voltage, full-scale output, input/output resistance, and temperature effects. Proper electrical connections and signal conditioning are required to accurately measure force with load cells.
The document discusses various types of meters used to measure voltage and current in DC and AC circuits. It describes DC ammeters, which use shunt resistors to measure higher currents beyond the range of the meter movement. Multi-range ammeters use multiple shunts and a range switch to extend the measurement range. DC voltmeters use a series resistor called a multiplier to limit the current through the meter movement. Multi-range voltmeters similarly use multiple multipliers and a range switch. AC meters rectify the input voltage before measuring to obtain the average value using a DC meter. Instrument transformers like current transformers and potential transformers are used to safely measure high currents and voltages in power systems.
- The document is an electrical and electronics laboratory manual containing instructions for various experiments.
- It includes two parts - Part A contains experiments related to basic circuit theorems like superposition, reciprocity, Thevenin's, Norton's theorems. Part B includes experiments on basic electronic components like PN junction, diode characteristics.
- The given experiment is about verifying Thevenin's and Norton's theorems for a given circuit. It describes the circuit diagram, theoretical background, procedure to determine equivalent Thevenin's voltage and resistance or Norton's current and resistance.
This document describes an improvement to corner fittings used in constructing sheet metal boxes. The corner fittings have angled flanges that allow adjacent sides of the box to be joined together at right angles. Lugs project inwardly from the flanges to reinforce the joints. When the sides are folded and the lugs bent inward, rigid box corners are formed without additional fasteners. The corner fittings allow for quick and easy assembly of rigid sheet metal boxes.
Сытник В. С. Основы расчета и анализа точности геодезических измерений в стро...Иван Иванов
В книге изложены вопросы теории и практики расчета, бценки
и анализа точности геодезических измерений, выполняемых при
возведении промышленных, жилых и общественных зданий й\цн-
женериых сооружений. На основе существующих в теории вероят^~—-
ностей
математической статистики и ошибок измерений рассмат
риваются методы расчета необходимой и достаточной точности гео
дезических измерений
применительно к определенным стадиям
строительно-монтажных работ и конструктивным решениям зданий
и сооружений. Значительное внимание уделено анализу точности
результатов геодезических измерений
Poialkova v.m. -_lifter-akademiia_(2007)Иван Иванов
The document is illegible as it contains random characters and symbols with no discernible words, sentences or meaning. It appears to be gibberish with no real information that can be summarized.
This document provides an introduction to a master's thesis that analyzes the legal and commercial issues in EU-Russia relations in the context of sanctions policy. It outlines the goals and structure of the thesis. The thesis will examine EU-Russia relations before and after sanctions were imposed in 2014 over Ukraine, the legal framework around the sanctions, and their impact on trade. It will also explore ways to optimize EU-Russia relations going forward. The introduction establishes that relations between the EU and Russia are an ongoing issue that significantly impacts international politics and economics.
Заковряшин А. И. Конструирование РЭА с учетом особенностей эксплуатацииИван Иванов
Показана роль конструкторского проектирования в обеспечении эффективности технического обслуживания РЭА по фактическому состоянию. В книге
взаимосвязанно решаются вопросы обеспечения ремонто- и контролепригодности
при конструировании РЭА. Ремонтопригодность рассматривается лак решающи”
фактор обеспечения эффективности применения аппаратуры. Область значений
конструктивных показателей РЭА определяется как результат решения задачи
оптимизации заданного качества функционирования.
The document provides guidance for directors of music in senior high schools on producing effective musical programs. It discusses various types of programs, considerations for program building such as attention, contrast and continuity. Organization, administration, publicity, programs/tickets, staging, lighting, costuming and other elements are covered. Experimental research was conducted, including visits to Radio City Music Hall and small theaters, to study professional practices.
1) Adolph W. Berkner of Cayuga, North Dakota invented an improved elevator bucket design.
2) Berkner's elevator bucket has a yieldingly supported bottom plate that can open under excessive weight to prevent overloading, and automatically closes when the weight reaches a predetermined amount to deliver accurate amounts.
3) The bottom plate is flexibly supported by a leather or metal strip attached to the top edge and backed by a metal strip, and is held closed by an arcuate leaf spring.
This document describes a radio navigation system that provides continuous indications of bearing and distance from a transmitter beacon to a receiver. It utilizes a single transmitter and receiver at the beacon location and a transmitter and receiver at the mobile location. The pulsed output of the distance measuring beacon is amplitude modulated with fundamental and harmonic bearing signals. At the mobile receiver, the distance is obtained from the timing of distance measuring pulses while the bearing is obtained by comparing the phase of the envelope wave components and reference signals.
This document describes a process for producing hydrocarbon drying oils through the polymerization of butadiene and styrene monomers in the presence of sodium catalyst. It discusses conducting the reaction in a reactor, then treating the product solution with an organic acid to convert the sodium into a filterable salt. The process aims to improve upon large-scale production by continuously feeding reagents to a reactor while removing the polymerized product, and pre-treating make-up materials to improve reaction efficiency.
This document describes improvements to a carbonating apparatus for producing aerated water. It details a conventional carbonator design and issues with maintaining proper carbonation levels and water temperature. The invention aims to address these issues by wrapping the carbonating chamber in helical coils of pipes, with one pipe carrying water and the other a refrigerant. This design cools the chamber directly to maintain carbonation levels while reducing operating pressures and refrigeration needs.
1. * GB780118 (A)
Description: GB780118 (A) ? 1957-07-31
Electric meter circuits
Description of GB780118 (A)
COMPLETE SPECIFICATION
Electric Meter Circuits
We, WESTERNELECTRIC COMPANY, INCOR
PORATED, of 195, Broadway, New York City,
New York State, United States of America, a Corporation of the State
of New York,
United States of America, do hereby declare the invention, for which
we pray that a patent may be granted to us, and the method by which it
is to be performed, to be particularly described in and by the
following statement :
This invention relates to the art of electrical measurements and more
particularly to meter circuits providing a meter with an electrically
suppressed zero.
Prior to this invention, zero suppression was obtained in various
ways, all of which had certain disadvantages. Bridge circuits
containing non-linear resistance arms are known. These bridges are
balanced at a predetermined impressed voltage and give an indication
of variations from the predetermined voltage. This effectively
provides the indicating meter with an electrically suppressed zero.
Examples of this type of circuit are disclosed in the United States
Patent of C. S. Bradley No. 280,563 granted 3rd
July, 1883 and in British Patent Specification 2,630 of 1886. The
principal objections to apparatus of this character are their large
size, their cost and their inconvenient cumbersomeness.
Measurements with circuits providing electrically suppressed zeros are
also made by applying an opposing voltage, thereby balancing out the
major part of the voltage being measured and employing a sensitive
voltage indicator for indicating the difference. The meter may either
be calibrated in impressed volts or in the difference volts. In either
case, the stability of the reference source used for opposing the
2. principal part of the voltage to be measured enters into the accuracy.
These reference voltages are generally quite unstable and require
frequent adjustment and calibration. Moreover, this arrangement is
also objectionable from the standpoint of weight, cost and bulk.
A third method consists of backwinding the spring of an otherwise
conventional meter so as to bias the needle against its initial stop.
The impressed voltage is raised to some predetermined limit before
deflection of the meter begins, thereby supplying a suppressed zero by
mechanical means. This arrangement, while satisfactory for some
purposes, is objectionable for at least three reasons. First, the
current through the meter is frequently substantially larger than the
normal rated current for the meter.
Second, mechanical instability arises by reason of the increased
bearing friction caused by backwinding the spring. Backwinding also
causes adjacent convolutions of the spring to come into contact,
thereby adding further mechanical instability. Third, upon suddenly
dropping the current to zero, the impact of the pointer against the
stop sometimes causes the pointer to bend. It is also known to connect
two sets of metal rectifiers arranged in parallel but with opposite
polarity, in series with an a.c. indicating instrument, the rectifiers
having an ohmic resistance which rapidly falls with increasing
current, so that the instrument with which it is connected has a
non-linear response.
This invention provides a suppressed zero meter circuit comprising a
galvanometer, having in series therewith a non-linear conductive
device having a substantially constant relatively low dynamic
resistance over a major part of the range of the meter and a very high
resistance for the initial part of the range, whereby energy falling
within the initial part of the range produces a very small response in
the meter whilst energy falling in the major part of the range
produces a nearly linear response. The nonlinear device may be in the
form of a diode of the dry type and is connected in' series with the
galvanometer. For cuiTents-,below a predetermined limit, for example,
corresponding to the avalanche breakdown point of the non-linear
device, very little deflection of the meter takes place. Above this
point, the current-voltage characteristic of the nonlinear device is
substantially linear over the major part of the range of the
galvanometer.
Thus, relatively large voltages may be impressed on the meter circuit
to produce only very small meter deflections up to the avalanche point
Beyond this point, small changes in circuit voltage will cause
relatively large deflections of the indicating instrument which are
nearly linearly proportional to the voltage changes. The dry type
diode is of small size and is very stable, so that zero suppression
3. may be provided without substantially increasing either the cost or
the bulk of the instrument.
The invention also comprises a suppressed zero meter circuit for
alternating current comprising an alternating current meter having in
series therewith a pair of substantially identical dry diodes
connected with opposed polarity in series with the meter, each diode
having an avalanche breakdown point at a current small compared to
that required for a full scale deflection of the meter and having a
substantially constant dynamic resistance for currents greater than
the current at said point
The invention may be better understood by reference to the
accompanying drawings in which:
Fig. 1 discloses a voltmeter circuit in accordance with this invention
for measuring direct voltages:
Fig. 2 is similar to Fig. 1 but includes shunt and series resistors
for the voltmeter and a protector device to protect the voltmeter
against accidental damage from reverse voltages;
Fig. 3 discloses a slight modification of the invention wherein a
plurality of nonlinear devices are connected in series for use in
higher voltage circuits;
Figs. 4, 5 and 6 are characteristics of a preferred non-linear device
suitable for the practice of the invention;
Fig. 7 discloses a typical suppressed zero meter scale;
Fig. 8 discloses the invention as used for measuring current supplied
to the load of a direct-current circuit; and
Figs. 9 and 10 show the invention adapted for measuring alternating
voltages.
Referring now to Fig. 1 it will be noted that the circuit comprises
simply a galvano meter 1 connected in series with a non-linear
conductive device 2. This latter device must have at least two ranges
of widely different dynamic resistance the initial range being of very
high resistance relative to the other range or ranges. The other range
or ranges must have a substantially constant dynamic resistance
whereby the response of the meter will be substantially linear. The
initial range may also be of substantially constant dynamic
resistance. A device which is especially adapted for the practice of
the invention is a commercially available silicon diode which has been
found to have a nearly constant dynamic resistance over the major
portion of its current range. The reverse current characteristic is
preferred for this purpose and consequently the polarity of the device
2, as symbolically illustrated in Fig.
1, is such as to give the least conduction for voltages of the
polarity indicated at test terminals T1 and T2. As this voltage is
slowly increased from zero, substantially all of the applied voltage
4. appears as a voltage drop across the device 2. When the avalanche
breakdown point is reached, the device 2 begins to rapidly increase
its conduction. Up to this point the meter 1 has shown only a very
small deflection. After this point is reached, the meter is found to
deflect very rapidly for a small change of applied voltage. Moreover,
the deflection has been found to be substantially linear with respect
to changes in supplied voltage above that point. This linearity adds
greatly to the usefulness of the invention.
To further understand this invention, reference may be made to Figs.
4, 5 and 6.
The portion of the characteristic just mentioned is that part denoted
as the reverse characteristic shown in the third quadrant of
Fig. 4. Here it will be noted that voltage changes from zero to
slightly above five volts will produce a current change in the order
of only two or three milliamperes. In this range the dynamic
resistance is very high and approximates the ohmic resistance.
After this point is reached, it will be noted that the current
increases almost linearly with only small changes in supply voltage.
This is represented by the substantially linear portion between points
A and B on the reverse characteristic of Figs. 4 and 6 where the
dynamic resistance is very much lower.
Fig. 6 shows on an enlarged scale only that part of the reverse
characteristic of Fig. 4 between applied voltages of 5 to 5.6 volts.
Fig. 6 also shows the reverse characteristics for two other
temperatures. The curve just described is for a temperature of 8705C.
The other two curves are for 60-C. and --30"C..
as shown. It will be noted that all three curves are nearly parallel
over their linear ranges and that the temperature effect is not too
great even for wide temperature changes.
Compensation. where desired. may be effected by using copper wire for
part of a resistor 4, referred to below with reference to Fig. 3.
taking into account the effect of the copper conductor in the coil of
meter 1
Diodes suitable for use in the practice of this invention are quite
small in size and are easily mounted within the enclosure of
commercially available instruments. Thus, their use does not in any
way increase the bulk nor substantially increase the weight of the
instruments as they are presently available.
It will also be noted that the desired characteristic is obtained
without requiring the galvanometer coil to carry currents
substantially in excess of its normal rating.
The invention has been described in relation to the reverse
characteristic between the points A and B of Fig. 4. It is also
evident that, under certain conditions, the portion of the forward
5. characteristic between the points C and D in the first quadrant of
Fig.
4 may also be used. This would provide zero suppression in a circuit
requiring much larger currents but at lower voltages. It will be
noted, however, that this forward characteristic is by no means as
linear as is the reverse characteristic. Consequently, the reverse
characteristic is preferred under ordinary circumstances. Acomparison
of Figs.
5 and 6 will further show the better linearity obtainable from the
reverse characteristic, as compared with the forward characteristic.
In comparing these figures, as well as comparing the first and third
quadrants of Fig. 4, it must be kept in mind that the two
characteristics are drawn to different scales so that the reverse
characteristic tends to appear much less linear than it would if it
were drawn to the same scale as the forward characteristic.
In Fig. 2 a protector diode 3 has been added as well as a series
resistor 4 and a shunt resistor 5. The protector diode 3 is poled in
the opposite direction from the suppressor diode 2 so that, should the
supply voltage be accidentally reversed, the meter will not be damaged
by a flow of excess current. The diode 3 should have a reverse voltage
rating higher than the voltage to be applied to terminals T1 and T2.
Resistors 4 and 5 may be made adjustable in accordance with
conventional practice. As used in this invention, it is convenient to
adjust resistor 4 to give a minimum deflection of the meter at the
lower end of its scale. The shunt resistor 5 may thereafter be
adjusted to give a full scale deflection for the maximum voltage to be
measured.
In the event that the voltage to be measured is in excess of that
which may be withstood by a single diode or non-linear resistor 2,
additional elements such as diodes 21 and 22 may be added in series as
shown in
Fig. 3.
The kind of zero suppression that may be obtained by the use of the
invention is illustrated by the meter scale shown in Fig. 7.
In comparing the scale of Fig. 7 with the reverse characteristic shown
in Figs. 4 and 6, it should be noted that at zero current the pointer
rests at the normal meter zero point
O of Fig. 7, corresponding with the origin 0 of Fig. 4. As the voltage
to be measured is increased from zero to 45 volts, the voltage changes
across the diode element 2 by an amount corresponding to the distance
from the point 0 to point A on the characteristic curve of Fig. 4. The
relatively small current represented by the horizontal distance from
the vertical axis to point A of the curve causes a small meter
deflection from zero to point A corresponding to the 45-volt point of
6. Fig. 7. Thereafter, an increase in voltage causes only a relatively
small voltage drop across the diode or non-linearelement 2 but the
current increases rapidly and almost linearly with the applied voltage
as indicated by the substantially linear scale in Fig. 7. Thus, for
example, if the voltage is increased from 45 volts to 55 volts, the
current will increase from point A to point B of the characteristic in
Fig. 4, corresponding to points A and B of the scale in Fig. 7. It
must be understood that these curves and the voltmeter scale shown in
Fig. 7 are merely illustrative of those that may be obtained. The
percentage of the entire meter deflection that may be used is
determined very largely by the particular diode selected, the voltage
range which is to be measured and the meter selected. A great variety
of characteristics are readily obtainable. Diodes suitable for this
purpose are readily obtained covering reverse voltage ranges from 3
volts to about 300 volts.
The invention may be easily used for measuring currents by employing a
resistance shunt such as resistor 6 in Fig. 8. The meter circuit
comprising galvanometer 1 and suppressor element 2 may correspond to
those shown in Figs. 1 and 2. The voltage drop across shunt resistor
6, as is well known, is proportional to the current supplied to the
load. The total current may be measured by a less sensitive instrument
8 connected in series with the rheostat 7 and the power supply. The
galvanometer 1, although a more sensitive instrument, will require a
substantial deflection of meter 8 before the voltage drop across shunt
resistor 6 is large enough to cause the suppressor element 2 to
increase its conduction. Thereafter, galvanometer 1 will deflect to
accurately show the change in current supplied to the load and may be
calibrated to read the actual value of this current.
Figs. 9 and 10 show the invention applied to the measurement of an
alternating current.
Here the galvanometer 9 is adapted for measuring alternating currents.
Connected in series with this galvanometer are two oppositely poled
asymmetrical non-linear conductors 2 and 2A having substantially
identical characteristics. A symmetrical nonlinear conductor may be
used in their stead providing it has a characteristic similar to that
shown in Fig. 6. It will be understood, of course, that a symmetrical
conductor would have identical characteristics for cur rents
flowing-in either direction.
For the alternating-current circuits shown in Figs. 9 and 10, no
substantial current flows through the meter 9 so long as the
alternating voltage source is below a predetermined limit. This limit
is caused to match the avalanche breakdown point, for example, near
the point A shown in the characteristic of Figs. 4 and 6. For applied
voltage greater than this amount, a suppressor element begins
7. conduction thereby causing deflection of the meter 9. It will be
understood that for one phase of the alternating voltage, one of the
elements 2 or 2A will be conducting in its forward direction and will
therefore have an exceedingly small drop across its terminals. The
zero suppression characteristic for this phase is provided by the
companion element. Upon the reversal of the voltage phase the two
elements 2 and 2A reverse their functions. For example, for the
connection shown in Fig. 9, if the voltage of the upper terminal of
the source is increasing in the positive direction, element 2 would be
conducting in its forward direction while element 2A is operating on
its reverse characteristic and would permit substantially no current
to flow in the meter circuit until after the voltage has increased to
a point corresponding to point A of its reverse characteristic. Upon a
reversal of polarity during the next phase, element 2A would be
conducting in its forward direction while element 2 would act as the
suppressor operating on its reverse characteristic.
The invention has been described as applicable to both direct voltage
and direct current measurements and to the measurement of alternating
voltages. It is obvious that it may also be used as an alternating
current measuring device by employing a current shunt such as shunt 6
shown for the direct current circuit of Fig. 8. Moreover, the
invention is readily extended to either the voltage coil or current
coil of a wattmeter whereby a wattmeter may be given a suppressed zero
power characteristic. When applied to the voltage coil the connections
are of the type shown in Figs. 1, 2 or 9 and when applied to the
current coil of a wattmeter the circuit would be of the type shown in
Fig. 8.
It will be evident that this invention provides unique advantages
heretofore unattainable in the suppressed zero metering art. The
diodes used have been found to be highly stable and the results
readily reproducible.
They are commercially available with reverse voltage ratings ranging
from 3 volts to about
300 volts. Zero suppression may be applied to a meter with very small
additional cost.
The resulting structure is of very light weight
and may be self-contained within the meter case. Nloreover, the
instrument coil is not required to carry current in excess of its
normel rating.
What we claim is:
1. A suppressed zero meter circuit comprising a ga1anomc-tcr having in
series therewith a non-linear conductive device having a substantiall-
constant relatively low dynamic resistance over a major part of the
range of the meter and a very high resistance for the initial part of
8. the range, whereby energy falling within the said initial part of the
range produces a very small response in the meter whilst clergy
falling in the said major part of the range produces a nearly linear
response.
2. A circuit according to Claim 1 wherein the non-linear device has a
voltage current characteristic including two current ranges of wideIy
different substntially constant dyna- mic resistance, the lower
resistance portion extending over a maicr part of the range of the
meter.
3. A circuit according to Claim 1 or 2 wherein the nonlinear device is
an avalanche breakdown dry diode. the avalanche breakdown point being
at the start of the said substantially constant dynamic resistance
portion.
4. A circuit according to Claim 3 in which a second diode having a
reverse voltage rating higher than the voltage of the circuit in which
the meter circuit is to be connected is connected in series with the
meter so as to give protection against accidental reversals of
voltage.
5. A suppressed zero meter circuit for alternating current comprising
an alternating current meter having in series therewith a pair of
substantially identical dry diodes connected with opposed polarity in
series with the meter, each diode having an avalanche breakdown point
at a current small compared to that requited for a full scale
deflection of the meter and having a substantially constant dynamic
resistance for currents greater than the current at said point.
6. A meter circuit according to Claim 3 wherein a plurality of diodes
are arranged in series.
7. A suppressed zero meter circuit arranged and adapted to operate
substantially as described with reference to and as shown in Fig. 1 or
Fig. 2 or Fig. 3 or Fig. 8 or Fig. 9 or Fig. 10 of the accompanying
drawings.