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# Short circuit test of three phase transformer

### Short circuit test of three-phase transformer MATLAB

• als to apply the fault, and then applying power to the low voltage bushing ter
• e the parameter of the equivalent circuit, voltage regulation and efficiency of the single / three-phase transformer. this is the main reason for doing SC and OC tests on the transformer
• e the values R s and X s of the series branch of the equivalent circuit. These impedances are usually very low, but appear higher in value when referred to the high voltage side
• The 3-phase short-circuit fault level PSC, in kA or in MVA(i) is given by the power supply authority concerned, from which an equivalent impedance can be deduced. A formula which makes this deduction and at the same time converts the impedance to an equivalent value at LV is given, as follows
• What is short circuit test? The short circuit test in the transformer is used to find the short circuit parameter such as copper losses, equivalent resistance, voltage regulation at full load condition. This test should be conducted at rated current condition. Why short circuit test to do
• In Short Circuit (SC) test, the primary or HV winding is connected to the AC supply source through voltmeter, ammeter, wattmeter and a variac as shown in figure. This test is also called as Reduced Voltage Test or Low Voltage Test Transformer Short Circuit Test Short Circuit Test of Transformer is performed on HV side and the supply voltage is so adjusted that rated current flows through the shorted secondary. As rated current is flowing through the shorted secondary that means that rated current will also flow in the primary because of Transformer action Three-phase power transformer efficiency was analysed in this paper. The results show that the open and short-circuit tests are an effective way to calculate the parameters of a non-ideal transformer. The efficiency, calculated at certain percentages of the rated load, is in the range of 88 to 90%. The maximum efficiency of a 1 kVA power transformer should be in the range of 94%. The transformer in the paper has a lower efficiency. This difference can be ascribed to the inaccuracy o Procedure for Short Circuit Test of Transformer Connect the circuit as shown in the figure. Keep the auto transformer output at its minimum voltage position and switch on the AC supply. Increase the applied voltage very slowly, and adjust it to get the current equal to the rated value of the winding The total reactance of a general circuit is equal to: X u003d XL + XC, where XL is the inductance of the circuit, and XC is the capacitive reactance of the circuit. 3 Measurement method The short-circuit impedance measurement of the transformer adopts the volt-ampere method. This method is suitable for single-phase and three-phase transformers Three phase transformer inner circuits In fact, a very low resistance approaching a short-circuit may be connected between point a and the neutral and only a very small amount of current will flow. This, as said above, is due to the reduc-tion of voltage E an because of neutral shift. In other words, unde

### Open Circuit Test and Short Circuit Test on Transformer

A three-phase transformer of a medium voltage substation has a power of 630000VA, a primary voltage of 13200V and a secondary voltage of 480V, with an impedance of 5%, which short-circuit level has the transformer at low voltage (secondary side) 1.1 Introduction to the short circuit phenomenon A short circuit (S/C) in an electrical circuit is a part of the circuit that for some reasons has become shorter than it should be. The current in an electrical circuit flows the easiest way and if two points in a circuit with different potentials are connected with lo SOLUTION. Nature of power during Short circuit: Under normal circumstances, the load current is mostly resistive with a high power factor. Since the impedance of the reactor is mostly reactive with a very low power factor and the magnitude of current drawn by the load is within nominal values, the voltage drop of the reactor is very small

### ECE 494 - Lab 3: Power Transformer Open and Short Circuit

• als on the excitation current.
• al
• OPEN CIRCUIT AND SHORT CIRCUIT TEST AND AUTOTRANFORMER OBJECTIVE: When you have completed this Experiment, you should be able to: Construct an equivalent circuit of a transformer on no load.. Predict the efficiency of a transformer over a range of loads. Complete the equivalent circuit
• Short circuit or Impedance test on Transformer The connection diagram for short circuit test or impedance test on transformer is as shown in the figure below. The LV side of transformer is short circuited and wattmeter (W), voltmere (V) and ammeter (A) are connected on the HV side of the transformer
• Hi all, I am designing a three phase 11000/433 Volts Delta/Star 50 Hertz transformer in Ansys Maxwell. It has 792 turns in 6 layers on HV side (132 turns per layer) and 18 turns in 2 layers (9 turns per layer). The resistance as I have calculated is 0.1325 ohms per phase of HV winding and 5.57..

short and open circuit test during Factory Acceptance Test (FAT) of the transformer. Then, the new models of the faulty transformer due to internal faults are built and simulated with the real data from the network and the transformer protection system behaviors due to these faults are studied In this paper, model of three-phase autotransformer with stabilizing winding is developed in EMTP for short-circuit studies. Currents and voltages are determined inside transformer windings during. At the end of this video tutorial, students will be able to perform the short circuit test of single phase transformer on Matlab Simulink to determine the se..

### What is Short Circuit Test in Transformer? Electrical4

We conduct open circuit and short circuit test on single phase transformer to determine the efficiency and regulation of a transformer on any load condition and at any power factor.Open circuit & short circuit test are also called as OC test & SC test on transformer.This method of finding the parameters of a transformer is called as an indirect loading method A short-circuit test is performed on the high-voltage side: Vline=500V, Iline=0.5 A, P3ϕ=86 W. a. Determine the equivalent circuit of the three-phase transformer bank. b. Find the efficiency of the transformer bank with a three-phase full-load for a power factor of 0.8 (lagging) Short-Circuit Current Calculations Three-Phase Short Circuits M 2 1 3 System A Available Utility Infinite Assumption 1500 KVA Transformer 480V, 3Ø, 3.5%Z, 3.45% X, 0.56%R I f.l. =1804A 25' - 500kcml Cu 3 Single Conductors 6 Per Phase Magnetic Conduit 2000A Switch KRP-C 2000SP Fuse 400A Switch LPS-RK-400SP Fuse 50' - 500 kcmil Cu 3 Single. referenced to the transformer base kVA short circuit = Short-circuit power SCA secondary = 3-phase short circuit amps at the secondary bus SCA primary = 3-phase short circuit amps at the primary bus. A few more words of caution! The impedance of a transformer must be the actual nameplate and not an assumed value This blog highlights commonly conducted tests on a three phase transformer. Voltage Ratio Test: This one is a simple and routine test of the transformer. For conducting this test, you need to supply the three-phase 415V to HV (High Voltage) windings, keeping LV (Low Voltage) open

Zero-sequence impedance on three-phase transformers. Short-circuit test. Harmonics on the no-load current. Power taken by fan and oil-pump motors. Determination of sound levels. Determination of capacitances between windings and earth, and between windings Transformer Short Circuit Current Calculation and Solutions Date Number of pages Appendices 14 June 2013 31 pages 0 page Summary There are three goals for the thesis. The first one is to introduce types of short-circuits. Th For 3-phase three-winding transformers, three measurements are made by the short circuit test. Z ps = Leakage impedance measured rn the primary with the secondary short-circuited and the tertiary open Positive sequence impedance test circuit for three-phase 2-winding transformer The positive sequence impedance is measured from a standard short circuit test (see figure right). In this test, one set of windings is shorted (typically the LV windings) and a three-phase voltage source is applied to the other set of windings

• The open circuit test on transformer is used to determine core losses in transformer and parameters of shunt branch of the equivalent circuit of transformer. 15. PROBLEM The O.C and S.C test data are given below for a single phase, 5 kVA, 200V/400V, 50Hz transformer Open circuit test or no load test on a transformer is performed to determine 'no load loss (core loss)' and 'no load current I 0 '. The circuit diagram for open circuit test is shown in the figure below. Usually high voltage (HV) winding is kept open and the low voltage (LV) winding is connected to its normal supply Some of the special tests carried out during the maintenance of the transformer are, Dielectric tests of transformer. Short-circuit test in transformer. Measuring the impedance of three-phase and zero-sequence of transformer. Measurement of the acoustic noise level of the measurement

Slip ring rotor has 3-phase windings. Three ends of which are stared and the other three ends are brought up and connected to 3 slip rings mounted in the shaft. Extra . resistance can be added in the rotor circuit. Squirrel cage rotor has short-circuited copper bars. Extra resistance can't be added as slip ring rotor. 6 through 8,333/10,417 KVA, single-phase, and 750/862 through 60,000/80,000/100,000 KVA, three-phase without load tap changing; and 3,750/4,687 through 60,000/80,000/100,000 KVA with load tap changing • (ANSI) IEEE C57.12.90-2010, standard test code for liquid-immersed distribution, power and regulating transformers and guide for short-circuit Experiment No: 2 Open circuit and short circuit tests on single phase transformer 1 Aim † To understand the basic working principle of a transformer. † To obtain the equivalent circuit parameters from OC and SC tests, and to estimate e-ciency & regulation at various loads. 2 Theory The physical basis of the transformer is mutual induction between two circuits linked by a commo to perform the sumpner's test on two identical transformers 3-5 2. to study the parallel operation of single phase transformers 6-8 3. to convert three phase to two phase conversion by scott-connection. 9-12 4. to find the polarity and turns ratio of a single phase transformer. 13-14 5. to study three phase to six phase conversion using Vector Group Test of Transformer. In a 3 phase transformer, it is essential to carry out a vector group test of transformer. Proper vector grouping in a transformer is an essential criteria for parallel operation of transformers. There are several internal connections of three-phase transformer are available on the market

### Open Circuit and Short Circuit Test on Transforme

1. Short Circuit Test The connection diagram and the equivalent circuit for the short circuit test are shown in Figure 3 and Figure 4 respectively. Short circuit test is used to find the leakage branch of the equivalent circuit of the given transformer. For supply voltage = V sc supply current = I sc Supply power = P sc the
2. • Develop transformer equivalent circuits from open-circuit and short-circuit test data. • Analyze transformer operation. • Calculate transformer voltage regulation and efficiency. • Use K-factor-rated transformer to solve nonlinear load problems. • Explain the four standard three-phase transformer configurations
3. g the short circuit test The measurement is carried out to determine the load-losses of the transformer and the impedanse voltage at rated frequency and rated current. The measurements are made separetely for each winding pair (e.g., the pairs 1-2, 1-3 and 2-3 for a three-winding transformer), and furthermore on the principal and extreme tappings 1 A single-phase 100 kVA, 1000/ 100 V transformer gave the following test results: open-circuit test 100 V, 6.0 A, 400 W short-circuit test 50 V, 100 A, 1800 W (a) Determine the rated voltage and rated current for the HV and LV sides. (b) Derive a Ans: Voltage required for the short-circuit test is about 5 percentage of the rated value.For a 200kVA,2200/220V transformer ,test on high voltage side would need the voltage of 2200*5/100 i.e 110 v and the current of 200*1000/2200 i.e 91 A. If the test is conducted in the low voltage side of the above transformer ,the voltage needed would be. Short Circuit Open Circuit Transformer Short Circuit Test Open Circuit Test Conclusion Source 3. A short circuit is an electrical circuit that allows a current to travel along an unintended path, often where essentially no (or a very low) electrical impedance is encountered A different form of short-circuit testing is done to assess the mechanical strength of the transformer windings, and their ability to withstand the high forces produced if an energized transformer experiences a short-circuit fault. Currents during such events can be several times the normal rated current

28.3 Problems on 3-phase ideal transformer It may be recalled that one can make a 3-phase transformer by using a bank of three numbers of identical single phase transformers or a single unit of a 3-phase transformers. 1. Three single phase ideal transformers, each of rating 5kVA, 200V/400V, 50 Hz are available of three-phase short-circuit currents # Three-phase short-circuit with Upstream network Overhead lines Synchronous generators Transformers (order of magnitude: for real values, refer to data given by manufacturer) E.g.: 20 kV/410 V; Sr = 630 kVA; Usc = 4 % 63 kV/11 V; Sr = 10 MVA; Usc = 9 % Cables X = 0.10 at 0.15 Ω/km three-phased or single. Two simple tests are used to determine the values for the parameters of the transformer equivalent circuit of Fig. 1 (a) and (b). The two tests are the short-circuit and open-circuit tests. If it is desired to find the parameters of the exact equivalent circuit of Fig. 2, it is customary to assume R1=a2R2 and X1 =a2X2

3 OPEN CIRCUIT & SHORT CIRCUIT TEST ON A SINGLE PHASE TRANSFORMER AIM: To perform open circuit and short circuit test on a single phase transformer and to pre-determine the efficiency, regulation and equivalent circuit of the transformer. APPARATUS REQUIRED: Sl. No. equipment Type Range Quantity 1 Voltmeter MI (0-300)V (0-150)V 1 no 1 n (a) To perform open circuit test on single PHASE transformer. (b) To perform short circuit test on the same transformer. (c) Calculate the complete parameters of the equivalent circuit of this transformer. (d) alculate the efficiency at 1/4th, 1/2th, 3/4th,full load and 1.25 times full load and plot the efficiency curve Vs load Short Circuit Test : The short circuit test is performed for determining the below mention parameter of the transformer. It determines the copper loss occurs on the full load. The copper loss is used for finding the efficiency of the transformer. The equivalent resistance, impedance, and leakage reactance are known by the short circuit test Fig. 1 shows short-circuit test circuit. Fig. 2 shows the short-circuit test equipment during cooling. Short-circuit test was performed by applying 6.9 kV on primary side of the model transformer using short-circuit generator. At this test, turn-on phase was controlled to be at zero degree in order to maximize short-circuit current 2. Bolted Line-To-Line Faults. Bolted line-to-line faults, Figure 1(b), are more common than three phase faults and have fault currents that are approximately 87% of the three phase bolted fault current.. This type of fault is not balanced within the three phases and its fault current is seldom calculated for equipment ratings because it does not provide the maximum fault current magnitude

### Short Circuit Test of Transformer Electrical Concept

1. ments with single-phase transformer. These experi-ments include open-circuit test, short-circuit test, load test, and short heat run test [3,4]. In the present work, all of the above-mentioned tests are replicated via MATLAB Simulink  without the support of any hardware what so ever. From our experience as educators, we can assert tha
2. ed. In this test normal voltage is applied on the low voltage side at rated frequency and high voltage side is the open condition that means there is no load on the transformer
3. Accordingly, value of short circuit current will also be different for primary and secondary windings. A less percentage impedance has both positive and negative effects. If Z% of the transformer is less, the short circuit current will be more which will produce more stress in insulation. This is a negative factor
4. Assume the fault current for a three-phase fault on the wye (or star) side to be 1pu. Then for a phase-phase fault the current will be 0.866pu. If the line-neutral voltage on the wye side is 1pu, the voltage on the delta side will be √3 times that value. I1, N1 & V1 prefer to delta side and I2, N2 and V2 refers to wye side

### Short Circuit Test of Transformer - your electrical guid

In the short circuit test, there is no electrical load driven by the transformer. The short circuit current is close to the rated current and only a small primary voltage (8 - 14% rated value) is enough to create a large amount of current. Therefore, the flux level in the core of the transformer will also be very small Question: An Open Circuit And Short Circuit Test Set Up On A Single-phase Transformer Is Modeled And Their Simulink Files Are Available To You. Please Use Those Models And Determine Needed Measurements For Open Circuit And Short Circuit Test. 1) Using OC And SC Values, Obtain The Real Transformer Equivalent Circuit And Verify Your Results With The Model Parameters. Clarification: Open circuit test gives the core losses also called as iron losses and shunt parameters of the equivalent circuit of transformer. Open circuit test and short circuit test both provide all the parameters of equivalent circuit. 3. Why OC test is performed on LV side? a) Simple constructio Three meters testing methods. When making three phase transformer no-load, load test, the instrument will judge if the wiring is correct automatically, and shows three phase voltage, current vector diagram. Finish load test under 1000kVA below distribution transformer full current for single machine 6. EE Board Exam October 1984. A single-phase, 25 kVA, 4800/240 volt transformer was given the short circuit test. With the secondary terminals short-circuited, 93.75 volts was applied on the primary so that the ammeter reads rated current and the wattmeter reads 162.74 watts, all on the primary side

### Transformer low-voltage short-circuit impedance test

SC(Short Circuit) Test: 1. Keeping the previous connections unchanged replace voltmeter by ammeter and short the other two phase with neutral as shown in the circuit diagram. 2. Run the Alternator set at rated speed and note down the excitation current with respect to short circuit current. 3 THREE-PHASE TRANSFORMER (Examples) Example 1 A 500-kVA, 3-phase, 50 Hz transformer has a voltage ratio (line voltages) of 33/11 kV and is delta/star connected. The resistances per phase are: high voltage 35 Ω, low voltage 0.876 Ω and the iron loss is 3050 W. Calculate the value of efficiency at full-load and one-half of full-load respectively.

The secondary side short circuit current for a 3 phase transformer = Volt amp transformer rating /(secondary voltage *1.732*impedance). For example, a 1500 kVA transformer with a 480volt secondary and a 5.75% impedance will have a calculated available short circuit secondary current of 31,374 amps The power required for these open circuit test and short circuit test on transformer is equal to the power loss occurring in the transformer. Open Circuit Test 1. Purpose. The purpose of this test is to determine the Core losses, no-load current, no-load resistance, no-load reactance and no-load power factor. 2. Diagram 3. Theor The open circuit test will show a power factor that is likely to be below 0.5 and probably in the realms of 0.3 or less. I am generalizing here and clearly some transformers (especially those used in flyback converters) have very low magnetization inductance but, for the average 50Hz/60Hz power transformer, the above will be the case

The wattmeter that is connected to the low voltage circuit is used to measure the input power and this value is taken to be the core loss in the transformer. Figure 2 - Open circuit test. Short circuit test. Figure 3 shows the connection diagram of the short circuit test. The low voltage side of the transformer is short circuited The let-through short circuit current of a 500kVA, 120/208V three-phase transformer is _____. 69,444A The maximum fuse size for a single-element, non-time-delay fuse serving a 10hp, three-phase motor is _____ A three phase fault on the 11kV winding would produce 60 MVA ÷ 33.08% ÷ 11000 V ÷ √3 = 9.51 kA. The transfer impedance determines SC current along with rated current of primary side. The 10% means the short circuit will present 1/10% or 10x rated current with a secondary short, regardless where the loss is highest

Test Result. The zero-sequence impedance is usually given as a percentage of the rated phase impedance. When the transformer has a three-limb core and no delta-connecter windings, the zero-sequence impedance is about 3060 %.. When the transformer has a delta-connected winding, the zero-sequence impedance is 0.81.0 times the corresponding short-circuit impedance Short circuit impedance and short circuit loss measurement for three-phase transformers during the testing is done by confirming the specimen under short circuiting condition to one side of the winding and application of the required voltage on the other side Power Factor Testing . The power factor test determines the power loss of the transformer's insulation system by measuring the power angle between an applied AC voltage and the resultant current.Power factor is defined as the cosine of the phase angle between voltage and current. For ideal insulation, the phase angle is 90 degrees, but in practice, no insulation is ideal The short circuit test in the transformer is always carried on the high voltage side mainly due to the power supply limitations used to perform the transformer's short circuit test. The primary purpose of performing a short circuit test in a transformer is to calculate the transformer's positive sequence impedance (Z) 6. Short-circuit impedance and load-loss measurement. The short-circuit loss and the short-circuit voltage show the performance of the transformer. These values are recorded and guaranteed to the customer and important for operational economy. The short-circuit voltage is an important criteria especially during parallel operations of the.

### Open Circuit and Short Circuit Test of Transformer? [ All

• For 1 phase transformer, use following formula. Let's calculate full load current in our example. Step 3 Calculate the short circuit current. We'll now calculate the actual short circuit current using the following formula. So, this is our Short circuit current. This will help you to decide the rating of circuit breaker
• In short circuit test of transformer preferably LV side is shorted and wattmeter ,ammeter and voltmeter readings are noted. From this test Ro2 and Xo2 (equivalent circuit parameters) are found. Copper losses at full load is also obtained (wattmete..
• e core losses in transformer and parameters of shunt branch of the equivalent circuit of transformer. The Short Circuit test on transformer is used to deter
• Parameters: Transformer rating (S): Rating in kVA. Voltage rating (V): Voltage rating of the secondary windings. Impedance (\(Z_{\%}\)): Per-unit impedance of the transformer in %. Can be found on the nameplate. Typically 4% to 10%. Notes: The transformer fault level calculator assumes that the transformer is supplied from an infinite bus

### Open and Short Circuit Test of Transformer Electrical4

1. Transformer Testing Methods for Single phase is tested by two basic methods. They are:-. Distribution Transformer. Open Circuit Test. Short Circuit Test. Though there are many more testing methods of a transformer like Polarity test, winding resistance test and load test. These test are done for small rated transformers or mainly for current.
2. Three-phase transformer winding short-circuit test To test a 2-layer winding fault, the lightning impulse voltage with an amplitude of 4 kV was injected. The measured response voltage waveform of each transformer phase is shown in Fig. 5
3. Fig. 2 Single phase equivalent circuit of three winding transformer All the parameters values are reduced to a common rating base and respective voltage bases. The primary, secondary and tertiary windings are respectively indicated by subscripts 1, 2 and 3 ### Open circuit and short-circuit test on three phase transforme

1. Short Circuit Calculations Only one calculation needs to be done for most 3 phase systems. This is for the per unit method. 3 Phase I SCA = KVA Base √3 KVLL total PUZ KVA Base = 10,000 Single Phase Two separate calculations must be done for single phase systems. I SCA = KVA Base ( KV line to line ) (total PUZ
2. 1. Operate a single phase transformer off-load, with a load applied and with a short circuit applied 2. Deduce the relationship between the secondary voltage and the loading and give reason for the deduction 3. Measure the off load voltage 4. Measure the short-circuit voltage and from this, calculate the short circuit current 5
3. 2. Bolted Line-To-Line Faults. Bolted line-to-line faults, Figure 1(b), are more common than three phase faults and have fault currents that are approximately 87% of the three phase bolted fault current.. This type of fault is not balanced within the three phases and its fault current is seldom calculated for equipment ratings because it does not provide the maximum fault current magnitude
4. My answer to What are the advantages and disadvantages of loading test over open circuit and short circuit test in Answer by Nikhil Nakka:Now basically we're talking about knowing performance of the transformer, i.e, we're trying to find its efficiency. Finding efficiency is done by two methods,DirectIndirectDirect: its direct loading of machine, find input an
5. The three phase transformer consist three transformers either separate or combined with one core. The primary and secondary of the transformer can be independently connected either in star or delta. There are three possible connections for a 3-phase transformer bank. They are delta-delta connection, star-star connection, star-delta connection and delta-star connection
6. Minimum dead time for short-circuit development, often equal to the time delay of a circuit breaker. uInstantaneous voltage. usc Transformer short-circuit voltage in %. U Network phase-to-phase voltage with no load. Un Network no
7. Fig. 2: Circuit diagram of parallel operation test of single phase transformer 2- Be certain that both switch ( w1 & w2) are open. 3- Apply a s mall percentage of the rated primary voltage across.  ### Calculation electric short circuit of single-phase and

1. Bolted Fault: A bolted fault is a short circuit of very high magnitude characterized by all three phases bolted together to create a zero impedance connection. Normally, short circuit calculations are performed on a bolted 3-phase fault condition because this establishes a highest current condition
2. Blocked Rotor or Short-Circuit Test: Figure: Circuit diagram for blocked rotor test. The blocked rotor test of an induction motor is same as the short-circuit test of a transformer. In this test, the shaft of the motor is connected so that it cannot move and rotor winding is short-circuited
3. The short circuit test is carried out with a low test voltage (380, 220 V). The arrangement for short circuit testing on aged transformers is to excite the HV windings and short the LV side as shown in Figure 10. For three-phase transformers, three-phase excitation is used, but current and voltage are measured in individual phases sequentially
4. als of the transformer, the amount of voltage at the secondary ter
5. A zigzag transformer is a special-purpose transformer with a zigzag or interconnected star winding connection, such that each output is the vector sum of two (2) phases offset by 120°. It is used as a grounding transformer, creating a missing neutral connection from an ungrounded 3-phase system to permit the grounding of that neutral to an earth reference point; to perform harmonic.  ### In Case Of 3 Phase Short Circuit In A System The Power Fed

Yes. This is a very practical application for standard single phase off-the-shelf transformers. Some typical voltage combinations are as follows: 480 volts three phase to 240 volts two phase, or 240 volts three phase to 480 volts two phase, or 240 volts three phase to 240 volts two phase. Please refer to us for an exact schematic Three phase transformation can be done in two ways, by using a single three-phase transformer or by using a bank of three single phase transformers. There are advantages and disadvantages to each option. A single 3 phase transformer costs around 15 % less than a bank of three single phase transformers. Again former occupies less space than later I'm given that after a short circuit test a one phase transformer rated at \\$2500\\$ kVA, \\$50000/10000\\$ at \\$50\\$ Hz yields the values of voltage, current and power as follows: \$\$720V, 225A,37947..

### Generator short-circuit characteristic test of waveform

Figure 1 - Example protection for a 1000 kVA, 13.2 kV Delta: 480 Y/277V, 5.75%Z dry-type transformer. The transformer is protected from short circuits by the primary fuses. The secondary circuit breaker provides overload protection at the full-load current of the transformer. Note that the primary fuse and secondary circuit-breaker. Hint A short circuit test is performed to find copper losses in a transformer. This test is usually done on the higher voltage side of a transformer winding to get an accurate value. Hint A sandwich-type winding is used in a three-phase shell type transformer, to balance magnetomotive force. 85). Why is the OC test is performed on the. Objective: To Determine the Efficiency and Regulation of a Single Phase Transformer by conducting (a) Open Circuit Test and (b) Short Circuit Test. The physical basis of the transformer is mutual induction between two circuits linked by a common magnetic field . Transformer is required to pass electrical energy from one circuit to another, via the medium of the pulsating magnetic field, as. 