This document discusses different methods for measuring resistance, including the Wheatstone bridge and Kelvin double bridge. It focuses on the Kelvin double bridge, which was developed to address limitations in measuring low resistances with a Wheatstone bridge due to lead and contact resistances. The Kelvin double bridge divides the lead resistance in half by connecting the galvanometer between two additional ratio arms, eliminating errors from the lead resistance and allowing accurate measurement of low resistances. It provides the working equation that shows the result is independent of the connecting lead resistance.
A Maxwell bridge is a modification to a Wheatstone bridge used to measure an unknown inductance (usually of low Q value) in terms of calibrated resistance and inductance or resistance and capacitance. When the calibrated components are a parallel resistor and capacitor, the bridge is known as a Maxwell-Wien bridge. It is named for James C. Maxwell, who first described it in 1873.
It uses the principle that the positive phase angle of an inductive impedance can be compensated by the negative phase angle of a capacitive impedance when put in the opposite arm and the circuit is at resonance; i.e., no potential difference across the detector (an AC voltmeter or ammeter)) and hence no current flowing through it. The unknown inductance then becomes known in terms of this capacitance.
Insulation resistance measurements are performed to verify that the state of dryness of the insulation of the various Winding , Bushings and the core are of acceptable values. In these presentation we will discuss about basic Insulation resistance test carried out in a two winding transformer.
Here we study the construction of hay's bridge, hay's bridge theory with expression, and example, hay's bridge phasor diagram. The Hay’s bridge is used for determining the self-inductance of the circuit. The bridge is the advanced form of Maxwell’s bridge.
A Kelvin bridge, also called a Kelvin double bridge and in some countries a Thomson bridge, is a measuring instrument used to measure unknown electrical resistors below 1 ohm. It is specifically designed to measure resistors that are constructed as four terminal resistors.
A Maxwell bridge is a modification to a Wheatstone bridge used to measure an unknown inductance (usually of low Q value) in terms of calibrated resistance and inductance or resistance and capacitance. When the calibrated components are a parallel resistor and capacitor, the bridge is known as a Maxwell-Wien bridge. It is named for James C. Maxwell, who first described it in 1873.
It uses the principle that the positive phase angle of an inductive impedance can be compensated by the negative phase angle of a capacitive impedance when put in the opposite arm and the circuit is at resonance; i.e., no potential difference across the detector (an AC voltmeter or ammeter)) and hence no current flowing through it. The unknown inductance then becomes known in terms of this capacitance.
Insulation resistance measurements are performed to verify that the state of dryness of the insulation of the various Winding , Bushings and the core are of acceptable values. In these presentation we will discuss about basic Insulation resistance test carried out in a two winding transformer.
Here we study the construction of hay's bridge, hay's bridge theory with expression, and example, hay's bridge phasor diagram. The Hay’s bridge is used for determining the self-inductance of the circuit. The bridge is the advanced form of Maxwell’s bridge.
A Kelvin bridge, also called a Kelvin double bridge and in some countries a Thomson bridge, is a measuring instrument used to measure unknown electrical resistors below 1 ohm. It is specifically designed to measure resistors that are constructed as four terminal resistors.
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
Contents include:- Methods of measurement, Wheatstone bridge method for winding resistivity of the specimen (For solid insulation & liquid insulation), Measurement of resistivity by simple dc Galvanometer.
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More examples of our work https://www.r-r-consult.dk/en/cases-en/
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Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
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The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
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Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
3. 3
• Simple and most basic bridge
• It mainly consists of four arms of
resistance P, Q; R and S.
• R is the unknown resistance under
experiment, while S is a standard
resistance.
• P and Q are known as the ratio arms.
• An EMF source is connected
between points a and b while a
galvanometer is connected between
points c and d
4. 4
• A bridge circuit always works on
the principle of null detection.
• Changing a parameter until the
detector shows zero and then use
a mathematical relation to
determine the unknown in terms
of varying parameter and other
constants.
• Here also the standard resistance,
S is varied in order to obtain null
deflection in the galvanometer.
• This null deflection implies no
current from point c to d, which
implies that potential of point c
and d is same.
7. • Wheatstone bridge use for measuring the resistance from a few ohms to
severalkilo-ohms.
• But error occurs in the result when it is used for measuring the low
resistance.
• Thisisthereasonbecauseofwhich the Wheatstonebridgeis modified, and
the Kelvin bridge obtains. The Kelvin bridge is suitable for measuring the
lowresistance.
• In Wheatstone Bridge, while measuring the low-value resistance, the
resistance of their lead and contacts increases the resistance of their total
measuredvalue.
7
8. •The r is the resistance of the contacts that
connect the unknown resistance R to
the standard resistance S.
•The ‘m’ and ‘n’ show the range between
which the galvanometer is connected for
obtaining a nullpoint.
•When the galvanometer is connected to point
‘m’, the lead resistance r is added to the
standard resistance S.
8
9. • Thereby the very low indication obtains for unknown
resistanceR.
• And if the galvanometer is connected to point n then
the r adds to the R, and hence the high value of
unknownresistanceisobtained.
• Thus, at point n and m either very high or very low
valueofunknownresistanceisobtained.
• So, instead of connecting the galvanometer from
point, m and n we chose any intermediate point say d
where the resistance of lead r is divided into two
equalparts,i.e.,r1 andr2
9
10. 10
Thepresence of r1 causes no errorinthe measurement of unknownresistance.
From equation (1), we get
11. 11
• The above equation shows that if the galvanometer connects at
point d then the resistance of lead will not affect their results.
• The above mention process is practically not possible to
implement. For obtaining the desired result, the actual
resistance of exact ratio connects between the point m and n
and the galvanometer connects at the junction of the resistor.
13. 13
• The ratio of the arms p and q are used to connect
the galvanometer at the right place between the
point mand n.
• Them andn reducethe effect of connecting lead.
• The P and Q is the first ratio of the arm and p
andq is thesecondarm ratio.
14. 14
• The galvanometer is connected between
the armsp andq at a point d.
• The point d places at the centre of the
resistance r between the point m and n for
removing the effect of the connecting lead
resistance which is placed between the
unknown resistance R and standard
resistance S.
15. 15
• The ratioof p/qis madeequaltothe P/Q.Under
balance conditionzerocurrentflows throughthe
galvanometer.The potentialdifference between
the pointa andbis equivalent to thevoltagedrop
between the pointsEamd.
• Now,
17. 17
The above equation is the working equations of the
Kelvins bridge.
The equation shows that the result obtains from
the Kelvin double bridge is free from the impact of
the connecting lead resistance.
