Oc and sc test on single phase transformer

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. Open Circuit(OC) and Short Circuit(SC) Test on Transformer Open circuit test and short circuit test on transformer are very economical and convenient because they are performed without actually loading of the transformer.because they furnish the required information without actually loading the transformer. In fact, the testing of very large a.c. machinery consists of running two tests similar to the open and short-circuit tests of a transformer. Open-circuit or No-load Test On Single Phase Transformers The circuit diagram for open circuit test is shown in the figure. A voltmeter(V), wattmeter(W), and an ammeter(A) are connected in LV side of the transformer.Usually high voltage (HV) winding is kept open and the low voltage (LV) winding is connected to its normal supply.Because we are going to find the max output voltage of transformer which is present at HV side.This is the reason why HV winding is open circuited. Procedure of Open Circuit(OC) Test • Switch on single phase AC supply,with the help of variac, increase the voltage until the voltmeter raeds the rated voltage of the LV side. • At theinstant of rated LV v...

This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. See Answer See Answer See Answer done loading Question:1 7.6 The readings of open circuit (OC) and short circuit (SC) tests on a single- phase 10 KVA, 450:120 V, 60 Hz transformer are: OC test on the secondary side with primary opened: V = 120 V, 1.- 4.2 A and W = 80 W SC test on the primary side with the secondary short circuited: V = 9.65 V, 1. = 22.2 A and W = 120 W Determine a. the approximate equivalent 1 7.6 The readings of open circuit (OC) and short circuit (SC) tests on a single- phase 10 KVA, 450:120 V, 60 Hz transformer are: OC test on the secondary side with primary opened: V = 120 V, 1.- 4.2 A and W = 80 W SC test on the primary side with the secondary short circuited: V = 9.65 V, 1. = 22.2 A and W = 120 W Determine a. the approximate equivalent circuit. b. the efficiency and voltage regulation when supplying full-load at 0.8 power factor lag. c. the efficiency when supplying half full-load at 0.8 power factor lag. 7.7 The results of the OC and SC tests on a single-phase, 20 kVA, 2200:220 V, 60 Hz transformer are: OC test on the secondary side with primary open V = 220 V, 1.2 = 4.2 A and W = 148 W SC test on the primary side with secondary short circuited V = 86 V, 1 = 10.5 A and W = 360 W Detemine the regulation and efficiency at full-load and at 0.8 power factor lag. 7.8 A single-phase, 25 kVA, 2000:200 V rated transformer has iron an...

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 transformer and potential transformers. For transformer with higher ratings we go for short circuit test and open circuit tests. Short Circuit Test:- Open Circuit Test of Transformer While testing a transformer through the open circuit method we first need to make the secondary open circuited. After that we need to add a watt meter and an ammeter in series to the primary winding. As the voltage supply will be rated voltage so there is no need of providing a voltmeter. When we give the supply voltage to the primary winding, the flux is set-up in the armature of the core of the transformer. There will be some The ratio of output power to the input power of a transformer is known as transformer efficiency at a particular load and power factor is defined as the output delivered by input power. The Voltage regulation =(no load voltage- full load voltage)*100/ no load voltage. From open circuit test and short ckt test this can be determined. Formula tobe used: W = I V COS X V = I R W = I* I R Xo = V / Im Ro = V / Iw Zo = Ro + j Xo Yo= 1 / Zo Where, W= watt meter reading in watt i.e power V= voltage in volts i.e voltmeter reading i = ammeter reading in amp i.e current Xo= reactance Z o= impedance Yo= admittance Impedance is the ...