This document summarizes key concepts related to transformers, including:
- All-day efficiency is a ratio measuring the energy delivered versus input over 24 hours, accounting for varying load.
- Autotransformers are cheaper than two-winding transformers but considered unsafe for distribution due to direct connection of voltages.
- Instrument transformers like current and potential transformers are used to measure high voltages/currents and connect to standard meters.
- Transformer connections like wye-wye, delta-delta, wye-delta are used in polyphase systems depending on voltage transformation needs.
Disadvantages of corona, radio interference, inductive interference between p...vishalgohel12195
Disadvantages of corona, radio interference, inductive interference between power and communication lines
Introduction
Disadvantages of corona.
Radio interference.
Inductive interference between power and communication lines
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This presentation explains about the parallel operation of transformers, along with sym. and unsym. voltage ratios, in brief.
Disadvantages of corona, radio interference, inductive interference between p...vishalgohel12195
Disadvantages of corona, radio interference, inductive interference between power and communication lines
Introduction
Disadvantages of corona.
Radio interference.
Inductive interference between power and communication lines
Thank you very much for checking out my presentation.
If you are a student or a faculty of an engineering college and need to create a presentation, you can contact me. Check out my profile to know how.
This presentation explains about the parallel operation of transformers, along with sym. and unsym. voltage ratios, in brief.
Generalized network constants and equivalent circuits of short, medium, long transmission line. Line performance: regulation and efficiency, Ferranti effect.
This chapter provides complete description of two port network parameters. It also provides relationship between different parameters. Also it provides condition for symmetry and reciprocity.
SWICTH GEAR AND PROTECTION (2170906)
DISTANCE RELAY
• There are mainly Three types of distance relay
1) Impedance Relay
2) Reactance Relay
3) Mho Relay
Tariff
The electrical energy produced by a power
station is delivered to a large number of
consumers. The consumers can be per-
suaded to use electrical energy if it is sold at rea-
sonable rates. The tariff i.e., the rate at which
electrical energy is sold naturally becomes atten-
tion inviting for electric supply company. The
supply company has to ensure that the tariff is
such that it not only recovers the total cost of
producing electrical energy but also earns profit
on the capital investment. However, the profit
must be marginal particularly for a country like
India where electric supply companies come un-
der public sector and are always subject to criti-
cism. In this chapter, we shall deal with various
types of tariff with special references to their ad-
vantages and disadvantages.
Generalized network constants and equivalent circuits of short, medium, long transmission line. Line performance: regulation and efficiency, Ferranti effect.
This chapter provides complete description of two port network parameters. It also provides relationship between different parameters. Also it provides condition for symmetry and reciprocity.
SWICTH GEAR AND PROTECTION (2170906)
DISTANCE RELAY
• There are mainly Three types of distance relay
1) Impedance Relay
2) Reactance Relay
3) Mho Relay
Tariff
The electrical energy produced by a power
station is delivered to a large number of
consumers. The consumers can be per-
suaded to use electrical energy if it is sold at rea-
sonable rates. The tariff i.e., the rate at which
electrical energy is sold naturally becomes atten-
tion inviting for electric supply company. The
supply company has to ensure that the tariff is
such that it not only recovers the total cost of
producing electrical energy but also earns profit
on the capital investment. However, the profit
must be marginal particularly for a country like
India where electric supply companies come un-
der public sector and are always subject to criti-
cism. In this chapter, we shall deal with various
types of tariff with special references to their ad-
vantages and disadvantages.
Application of Capacitors to Distribution System and Voltage RegulationAmeen San
Application of Capacitors to
Distribution System and Voltage
Regulation
POWER FACTOR IMPROVEMENT,
System Harmonics
Voltage Regulation
Methods of Voltage Control
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Speed Control Of Separately Excited Dc Motor Using A High Efficiency Flyback ...IJERA Editor
This paper deals with Speed control of separately excited DC motor using flyback converter with a new non complementary active clamp control method to achieve soft switching and high efficiency for heavy motor load and light load conditions. This is quite attractive for low power application with universal ac inputs, such as external adaptors. With the proposed control technique, the energy in the leakage inductance can be fully recycled. The soft switching can be achieved for the main switch and the absorbed leakage energy is transferred to the output and input side. In the Proposed model the resistive and DC motor is connected to flyback converter and it is simulated with different nominal voltages and rated speed is controlled at different levels for the N-type active clamp flyback converter and P-type active clamp flyback converter respectively. N-type active clamp flyback converter is suitable for high speed variation applications and P-type active clamp flyback converter is suitable for low speed variation applications.
Automatic load sharing of transformer using microcontrollerPrakhar Anand
1. ABSTRACT:-
The transformer is a static device, which converts power from one level to another level.
The main aim is to protect the transformer under overload condition by load sharing.
Due to overload on transformer, the efficiency drops and windings get overheated and may get burnt.
Thus by sharing load on transformer, the transformer is protected. This will be done by connecting another transformer in parallel through a micro-controller.
The micro controller compares the load on the first transformer with a reference value. When the load exceeds the reference value, the second transformer will share the extra load.
Therefore, the two transformer work efficiently and damage is prevented. Main modules used here are sensing unit, control unit and micro-control.
A GSM modem is also used to inform the control station about switching.
The advantages of the project are transformer protection, uninterrupted power supply, and short circuit protection.
2. OBJECTIVE:-
To design & fabrication of a hardware which will monitor the performance of the load sharing process by taking power consumed by the load into consideration.
3. INTRODUCTION:-
Transformer is the vital component in the electric power transmission and distribution system.
The problems of overloading, voltage variation and heating effects are very common. It takes a lot of time for its repair and also involves lot of expenditure.
This work is all about protecting the transformer under overload condition. Due to overload the efficiency drops and the secondary winding gets overheated or it may be burnt.
So, by reducing the extra load, the transformer can be protected. This can be done by operating another transformer in parallel with main transformer through microcontroller and change over relay.
The microcontroller compares the load on the first transformer with a reference value. When the load exceeds the reference value, the slave transformer will automatically be connected in parallel with first transformer and share the extra load.
Therefore, a number of transformers work efficiently under overload condition and the damage can be prevented.
In this work, the slave transformers share the load of master transformer in the case of over load and over temperature conditions.
A sensor circuit containing microcontroller, current transformer etc. is designed to log the data from master transformer and if it is found to be in overload condition, immediately the slave transformer will be connected in the parallel to the master transformer and the load is shared.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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Introduction
Working Principle
Step Down and Step Up Cycloconverter
Single phase to single phase cycloconverter
Mid-Point and Bridge type cycloconverter
Advantages and disadvantages
Applications
ETAP is the Global Market and Technology Leader of power systems solutions for a broad spectrum of sectors including Generation, Transmission, Distribution, Transportation, Industrial, and Commercial
There are numerous systems in use today that convert the fixed
voltage and fixed frequency a.c. supply into variable voltage or /and variable frequency supply using power semiconductor devices. The simplest forms of ac-to-ac converters are the a.c. voltage controllers that
convert fixed voltage fixed frequency into variable voltage fixed frequency. These voltage controllers are also called a.c. choppers or a.c. voltage regulators. Some of the applications are motor drive systems; electric furnaces heat control, light dimmers, HVAC systems, welding and other industrial applications. This chapter discusses the single phase and three-phase a.c. voltage controller (a.c. choppers) and their performance with resistive and resistive-inductive loads.
The ac-to-ac power converters available in industry today do not actually convert power directly from a.c. power of one frequency to a.c. power of another frequency. Instead, these converters first convert
electrical power to d.c. using a rectifier, and then convert power back into a.c. using an inverter.These are called two-stage converters. However,
a cycloconverter is a frequency changer that converts an a.c. supply of fixed input frequency directly to an a.c. output of another frequency.
Cycloconverters not only eliminate the problem of having multiple systems to perform a single function, they also limit the flow of power to a single switch at any one period in time. Therefore, there is no bus link,
d.c. or otherwise, included in a cycloconverter topology between power input and power output.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
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Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
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.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
1. ALL-DAY EFFICIENCY
-> is defined as the ratio of the energy (kilowatt-hours) delivered
by the transformer in a 24-hour period to the energy input in the
same period of time.
-> to determine the all-day efficiency, it is necessary to know
how the load varies from hour to hour during the day.
Example:
The transformer of example 18 operates with the following loads
during a 24-hr period: 1 ½ times rated kva, power factor = 0.8,
1hr; 1 ¼ times rated kva, power factor = 0.8, 2hr; rated kva, power
factor = 0.9, 3hr; ½ rated kva, power factor = 1.0, 6hr; ¼ rated
kva, power factor = 0.8; no-load, 4hr. Calculate the all-day
efficiency.
2. Solution:
Energy output, kw-hr Energy losses, kw-hr
W1 = 1.5 x 5 x 0.8 x = 6.0 (1 ½)2
x 0.112 x 1 = 0.252
W2 = 1.25 x 0.8 x 2 = 10.0 (1 ½)2 x 0.112 x 2 = 0.350
W3 = 1 x 5 x 0.9 x 3 = 13.5 1 x 0.112 x 3 = 0.336
W6 = 0.5 x 5 x 1.0 x 6 = 15.0 (1/2)2 x 0.112 x 6 = 0.168
W8 = 0.25 x 5 x 1.0 x 8 = 10.0 (1/4)2 x 0.112 x 8 = 0.056
____
Total. . . . . . . . 54.5 Iron = 0.04 x 24 = 0.960
_____
Total. . . . . . . . .. . . . 2.122
All-day Efficiency = (1 – 2.122/54.5 + 2.122) x 100 = 96.25%
3. AUTOTRANSFORMERS
In principle and in general construction, the autotransformer
does not differ from the conventional two-winding transformer, but it
differ from the way in which the primary and the secondary are
interrelated. In conventional transformer, the primary and secondary
windings are completely insulated from each other but are magnetically
linked by a common core. In autotransformer, the two windings, primary
and secondary, are both electrically and magnetically interconnected: a
part of the single continuous winding is common to both primary and
secondary.
Two ways in constructing Autotransformer:
1.] in one arrangement, there is a single continuous winding with taps
brought out at a convenient points determined by the desired secondary
voltages.
2.] in other arrangement, there are two or more distinct coils which are
electrically connected to form a continuous winding.
4. Autotransformers are cheaper than conventional two-
winding transformers of similar rating. They also have a better
regulation, and operate at a higher efficiencies. However, they are
considered unsafe for use on ordinary distribution circuits
because the high-voltage primary circuit is directly connected to
the low-voltage secondary circuit.
They are frequently used in connection with the starting
of certain types of ca motors, so that lower than line voltage is
applied during the starting period.
INSTRUMENT TRANSFORMER
Instrument transformers are used to measure
comparatively high values of current or voltage.
Two kinds of Instrument Transformers:
1.] Current Transformer
-> is used with an ammeter to measure the current in an ac
circuit.
-> in practice, it is connected to ordinary 5-amp ammeters
5. -> it has a primary coil of one or more turns of heavy wire, which is
always connected in series in the circuit in which the current is to be
measured.
-> the secondary has many turns of comparatively fine wire, which
must always be connected across the ammeter terminals.
2.] Potential Transformers
-> is used with a voltmeter to measure the potential difference, or
voltage in an ac circuit.
-> are generally employed with standard 150-volt voltmeters.
Clamp-on or Clip-on Ammeter
-> a practical design of current transformer.
-> has a laminated core so arranged that it may be opened out at a
hinged section by pressing a trigger.
-> when the core is opened, it permits the admission of the current-
carrying conductor, whereupon the trigger is released and the core is
closed tight by a spring. The current-carrying conductor acts as a
single-turn primary, while the accurately wound secondary is
permanently connected to the ammeter conveniently mounted in the
handle.
6. Important Aspects of Current Transformer
-> is that its secondary must never be permitted to be open-circuited because,
unlike distribution and power transformers which are connected to constant-
potential sources, the voltage across the primary winding varies over a wide range as
the load changes.
Important Aspects of Potential Transformer
-> Potential Transformer are carefully designed, extremely accurate-ratio step-down
transformers. They are used with standard low-range voltmeters, the deflection of
which , when multiplied by the ratio of transformation, gives the true voltage on the
high side. They differ very little from the ordinary two-winding transformers, except
that they handle a very small amount of power.
TRANSFORMER POLARITY
Transformers are often connected in parallel to supply a common load, in much the
same way as are alternators and dc generators for the same purpose. Two or three
transformers are connected together so that they may be used in polyphase systems.
It is necessary that the polarity of the transformers be known before the connections
are made.
7. Polarity of a Transformers
-> refers to the relative directions of the induced voltages in the primary and
secondary windings with respect to the manner in which the terminal leads are
brought out and marked. Standard notations are additive polarity and subtractive
polarity.
PARALLEL OPERATION OF TRANSFORMERS
Several important conditions must be fulfilled if two or more transformer are to
operate successfully in parallel to deliver a common load.
These important conditions are:
1.] the voltage ratings of both primaries and secondaries must be identical. This
implies that the transformation ratios are the same.
2.] the transformers must be properly connected with regard to polarity.
3.] the equivalent impedances should be inversely proportional to the respective
kilovolt-ampere ratings.
4.] the ratio of the equivalent resistance to the equivalent reactance (Re:Xe) of all
transformers should be the same.
*The parallel operation of two or more transformers requires that the primaries be
joined to the same source and that the secondaries be connected to the same load.
8. No-load Operation
When the secondary load is removed, with switch S open, the primaries
will still be energized and secondaries will still remain connected in parallel. Since
the latter are in phase opposition with respect to each other, no current can circulate
in these windings if the induced voltages are exactly equal; this condition can exist
only if the ratio of transformation of the two transformers are exactly equal. If the
transformer 1 has a ratio of transformation a1 which is different that of transformer
2, which has a ratio of transformation a2, the circulating current in the secondary Ic
will be
Ic = (a1-a2)Vs / a1Ze1+a2Ze2
Where: Ze1 = equivalent impedance of transformer 1 in secondary terms
Ze2 = equivalent impedance of transformer 2 in secondary terms
9. Example 27:
The following information is given in connection with two transformers that are
connected in parallel:
Transformer 1 Transformer 2
rating = 25 kva rating = 35 kva
2,360/230 volts 2,300/230 volts
Ze = 0.08, in secondary terms Ze = 0.06, in secondary terms
Calculate the secondary circulating current at no load.
Solution:
a1 = 2,360/230 = 10.26 a2 = 2,300/230 = 10
Ic = (10.26 – 10) 230/ [(10.26 x 0.08) + (10 x 0.06)]
= 59.8 / (0.821 + 0.6)
= 42.1 A
10. Load Operation—Equal Ratios of Transformation
When two transformers having equal ratios of transformation are connected in
parallel, the total load current will divide between them in inversely as their
equivalent impedances.
Example:
The following information is given for two transformers connected in parallel and
delivering a total load of 300 kva:
Transformer 1 Transformer 2
Rating = 150 kva Rating = 250 kva
6,900/230 volts 6,900/230 volts
Ze = 9.4, in primary terms Ze = 5.8, in primary term
Calculate the load current and kilovolt-amperes delivered by each transformer.
11. Solution:
Total current IT = 300,00 / 6,900 = 43.5 amp
I1 / I2 = 5.8 / 9.4
I1 = (5.8 / 9.4) x I2
Also,
IT = I1 + I2
43.5 = [(5.8 / 9.4) x I2] + I2 = 1.617 I2
I2 = 26.9 amp
I1 = 43.5 – 26.9 = 16.6 amp
Therefore :
kva1 = 6.9 x 16.6 = 114.4
kva2 = 6.9 x 26.9 = 185.6
total = 300 kva
12. Load Operation—Unequal Ratios of Transformation
When two transformers having unequal ratios of transformation are
connected in parallel, the total load current will drive in accordance with the
following equations:
I1 = [(a2 – a1)Vs + (a2Ze2It)] / [(a1Ze1) + (a2Ze2)]
I2 = [(a1 – a2)Vs + (a1Ze1It)] / [(a1Ze1) + (a2Ze2)]
Example:
The transformer of example 27 deliver a total load of 46 kva. Calculate the
secondary currents and the kilovolt-ampere load of each one.
Solution:
a1 = 10.26 a2 = 10 Ze1 = 0.08 Ze2 = 0.06
It = 46,00 / 230 = 200 amp
I1 = [(10-10.26)230 + (10 x 0.06 x 200)] / [(10.26 x 0.08) + (10 x 0.06)]
= (-59.8 + 120) / 1.421 = 60.2 / 1.421 = 42.4
I2 = [(10.26 – 10)230 + (10.26 x 0.08 x 200)] / [(10.26 x 0.08) + (10 x 0.06)]
= (59.8 + 164) / 1.421 = 223.8 / 1.421 = 157.6
Kva1 = 42.4 x 0.23 = 9.75
Kva2 = 157.6 x x0.23 = 36.25
13. Three- phase Transformer Connections
Transformers that must handle a considerable amount of power are
generally grouped together in banks for polyphase service. In three-phase systems,
two or three identical transformers may be used in a bank for this purpose.
Four standard ways of connecting 3-phase transformer banks:
1.] wye-wye
2.] delta-delta
3.] delta-wye
4.] wye-delta
1.] WYE-WYE CONNECTIONS
If the ratio of transformation is a, the same ratio will exist between the line
voltages on the primary and secondary sides. This connection will give satisfactory
service only if the three-phase load is balanced. When the load is unbalanced, the
electrical neutral will shift from its exact centre to a point that will make the three
lone-to-neutral voltages unequal. The advantage of this system of connections is
that the insulation is stressed only to the extent of the line-to-neutral voltage, which
is 58% of the line-to-line voltage.
14. 2.]DELTA-DELTA CONNECTION
This arrangement is generally used in systems in which the
voltages are high and especially when continuity of service must be
maintained even though one of the transformers should fail. When
one of the transformers is removed from a delta-delta bank,
operation continues on what is known as open delta. The ratio of
transformation existing between primary and secondary line voltage
will be exactly the same as that of each transformer.
3.] WYE-DELTA CONNECTION
This scheme of connection, is generally employed where it is
necessary to step-up the voltage, for example, at the beginning of a
high-tension transmission system. On the high sides of transformer,
insulation is stressed only to the extent of 58% of the line-line
voltage.
15. 4.] WYE -DELTA CONNECTION
This connection is the reverse of the delta-wye connection. It
is used principally where the voltage is to be stepped down. It is also
employed in moderately low-voltage distribution circuits for
stepping down from transmission voltages of 4,000 – 8,000 volts to
230 and 115 volts. The points made concerning delta-wye
connections supply equally well here.
THE V-V CONNECTION
If one of the transformers of a delta-delta bank is removed
and a three-phase source is connected to the primaries, three equal
3-phase voltages will be measured at the secondary terminals at no
load. This method of transforming 3-phase power , using 2
transformers, is called open delta or V-V connection.
16. THE T-T CONNECTION
Another 2-transformer method
that can be used to transform 3-phase
power from one voltage to another is the
T-T connection. It was first proposed
by Charles F. Scott and is frequently
called the Scott connection.
17. MAIN TRANSFORMER
-must have at least two
primary and two secondary
coils so that a center tap
may be brought out from
each other.
18. TEASER TRANSFORMER
-must have primary and
secondary windings the
numbers of turns of w/c are
86.6% of the respective turns
of the main transformer.
19. FIG. 212
The kilovolt-ampere ratings of the MAIN
and TEASER TRANSFORMER will be exactly the
same, even thought the voltage across the latter
is only 886.6% of that across the former.
The reason for this is that kVA loads carried
by the TWO HALVES of the MAIN
TRANSFORMER are out of phase by 6O
electrical degrees; the result is that when these
are vectorially added, their sum equals the kVA
load on the teasier transforrmer.
20. THREE-PHASE TRANSFORMER
-more economical to use a three phase
transformer than, as previously discussed, a
bank of three single phase transformer.
Proper flux densities are maintained
because the three phase currents are
displaced 120 electrical degrees w/ respect to
each other.
21. TWO GENERAL ARRANGEMENT OF
THE WINDINGS AND THE CORE
CORE TYPE, the three primary & secondary windings
surround a considerably part of the magnetic core.
FIG. 214a
SHELL TYPE, the magnetic circuits surround a
considerable portion of the 3 phase primary &
secondary windings.
Advantage:
The former transformer can be operated in open
DELTA should one of the windings be damaged;