Why does SC test require reduced voltage?

The rated current should flow in the winding if the lower value of voltage is applied during the test. It is convenient to conduct the test on the HV side because the meters used for the test are less range.

Why SC test is performed at rated current?

The SC test is conducted on HV side due to the two main reasons. Therefore, the rated current is easily achieved at HV side (due to the low current value) as compared to the LV side. On the other hand, if we short the HV terminals by connecting measuring instrument on LV side, voltage in the secondary is zero.

What is SC in transformer?

Since the applied voltage Vsc is short circuit voltage in the transformer and hence it is quite small compared to the rated voltage, so, we can neglect the core loss due to the small applied voltage.

How much current is in a transformer?

If for some reason you need a larger transformer to operate appliances, you still divide the wattage by the voltage to find the current. For a 120-volt primary, 2000-watt transformer, divide 2000 by 120 for the current (2000 Watts /120 volts =16.67 amps). For a 240-volt, 3000-watt transformer, the current is 12.5 amps.

Why do we use SC and OC test of transformer?

Why is it necessary to conduct OC and SC tests? It is necessary to know the impedance of the transformer in order to calculate its voltage regulation and efficiency. The impedance and other circuit parameters can be determined by conducting simple no-load tests.

Why high voltage side of transformer is open?

The high-voltage side is generally kept open because the current in high-voltage winding is less compared to that on low-voltage winding.

What is the high voltage side of a transformer?

Transformer High Voltage(HV) Side The transformer high voltage side carries the high voltage or HV windings. The transformer’s high voltage side carries high voltage and low current. The transformer high voltage side winding having more turns than the low voltage side.

What is OC and SC test in transformer?

The open circuit and short circuit test are performed for determining the parameter of the transformer like their efficiency, voltage regulation, circuit constant etc. These tests are performed without the actual loading and because of this reason the very less power is required for the test.

What is OC and SC test?

Mainly two tests carried out on the electrical transformer that are open circuit and short circuit test of the transformer also known as SC and OC test. The purpose of these tests is to determine the parameter of the equivalent circuit, voltage regulation and efficiency of the single / three-phase transformer.

How do you calculate the voltage of a transformer?

Divide the number of secondary windings by the number of primary windings, and multiply the source voltage by this ratio. This will give you the output voltage.

How does a transformer change voltage?

A Transformer changes the voltage level (or current level) on its input winding to another value on its output winding using a magnetic field.

Why HV side is open in OC test?

In short circuit test we have to pass rated current through the short circuited side. Therefore we select High Voltage (HV) side normally for short circuiting, because it’s rated current is less and therefore it is easy to short.

How to perform short circuit test on transformer?

The connection diagram for short circuit test on transformer is shown in the figure. A voltmeter, wattmeter, and an ammeter are connected in HV side of the transformer as shown. The voltage at rated frequency is applied to that HV side with the help of a variac of variable ratio auto transformer.

What is an SC test in a transformer?

SC test, i.e short circuit test is a test conducted to find the winding loss in a transformer . Winding loss/heat loss/I square R loss/ copper loss (Alluminium loss if the winding material is Alluminium) are its other names.

Why rated current flows through the shorted secondary of a transformer?

As rated current is flowing through the shorted secondary that means that rated current will also flow in the primary because of Transformer action. The supply voltage required for the flow of rated current in the shorted secondary is around 2-12\% of rated voltage.

What is the difference between Watt-meter reading and voltmeter reading in transformer?

As the voltage applied for full load current in a short circuit test on the transformer is quite small compared to the rated primary voltage of the transformer, the core losses in the transformer can be taken as negligible here. Let’s say, voltmeter reading is V sc. The watt-meter reading indicates the input power during the test.