What is referred impedance?

Recollect: The Reflected (referred) impedance (the impedance looking into the primary side of the transformer) When we move an impedance from the secondary to the primary side of the transformer we multiply by the turns ratio squared.

What does mean by primary referred to secondary?

If the equivalent circuit parameters are referred to as the primary. The secondary parameters must be divide with the transformation ratio K except for the secondary current where it multiplied. If the equivalent circuit parameters are referred to the secondary.

What is OC and SC test on single phase transformer?

Suppose if the transformer is step-up transformer, then we carry out the SC test on secondary side (HV side) while primary or low voltage side is shorted. From the OC test we get, shunt branch parameters referred to the LV side and from SC test we get series branch parameters referred to HV side.

What is transformer and its working principle?

A transformer operates on the principle of electromagnetic induction. It has a magnetic core over which two sets of windings, termed as primary and secondary, are suitably placed. When one of the windings is connected to an AC supply, an emf is induced on the other winding which is proportional to the number of turns.

Why is equivalent impedance referred to primary or secondary side?

Equivalent impedance of transformer is essential to be calculated because the electrical power transformer is an electrical power system equipment for estimating different parameters of the electrical power system which may be required to calculate the total internal impedance of an electrical power transformer.

What is LV and HV side of transformer?

The test is conducted on the high-voltage (HV) side of the transformer where the low-voltage (LV) side or the secondary is short circuited. A wattmeter is connected to the primary. An ammeter is connected in series with the primary winding.

What is the transformation ratio?

The turns ratio, or the turns-to-turns ratio, is the ratio of the number of turns in the primary to the number of turns in the secondary. A step-up transformer is a transformer with the source connected to the winding with fewer turns and the load connected to the winding that has a larger number of turns.

Why UPF wattmeter is used in SC test?

LPF wattmeter is used to measure power in inductive circuits. Inductive circuits have the property of lagging power factor and hence these wattmeters are used. Resistive circuits have unity power factor hence UPF wattmeters are used to measure power in these circuits.

Why LV side is shorted in SC test?

In the short circuit test, usually, the low voltage side is short-circuited by a thick conductor. The reason for short-circuiting the low voltage side is as follows: The rated current on the high voltage (hv) side of a transformer is less than the low voltage (lv) side of the transformer.

What is the two types of transformer?

There are two types of transformers, namely: Step down and Step up transformers. secondary coils. most domestic equipment.

How do you find equivalent resistance referred to primary?

And the total resistance at primary winding is ( R1 + R2/K2 ) which is known as the equivalent resistance of the transformer as referred to primary . and It may be demarked as R01= R1+ R2’= R1 +R2/K2.

How is the primary current related to the secondary current?

The load component I 2 ′ flows through the primary winding of transformer and induced voltage across the winding is E 1 as shown in the figure right. This induced voltage E 1 transforms to secondary and it is E 2 and load component of primary current I 2 ′ is transformed to secondary as secondary current I 2. Current of secondary is I 2.

How is no load current related to working current?

Hence, I 1 = I 1 ’. The no-load current is further divided into two components called magnetizing current (I m) and working current (I w ). These two components of no-load current are due to the current drawn by a non-inductive resistance R 0 and pure reactance X 0 having voltage E 1 or (V 1 – primary voltage drop).

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Where are the core losses in the equivalent circuit?

In Fig.2, the inductor Lm1 representing the core magnetization and the resistor Rc1 representing the core losses (hysteresis and eddy current losses) have been connected in parallel and located in the primary side of the transformer equivalent circuit.