How do you calculate the resistance of a transformer?

In this method of measurement of winding resistance, the test current is injected to the winding and corresponding voltage drop across the winding is measured. By applying simple Ohm’s law i.e. Rx = V ⁄ I, one can easily determine the value of resistance.

What is the resistance of primary winding in a transformer?

The primary winding should have ideally zero resistance but it needs an impedance to prevent it shorting out the AC power applied. So, it has inductance and, for a typical power transformer that might be in the realm of 10 henries for 50/60 Hz applications.

How do you find the leakage reactance of a transformer?

X1 and X2 = leakage reactance of primary and secondary winding resp. Z1 and Z2 = Primary impedance and secondary impedance resp. Z1 = R1 + jX1 …and Z2 = R2 + jX 2 . E1 and E2 = induced emf in primary and secondary winding respectively.

How do you calculate XR on a transformer?

An example is below. The X/R ratio of a transformer is simply the imaginary part of its impedance divided by the real part of its impedance. When used in conjunction with the X/R ratio above the transformer’s primary, it’s used to calculate the maximum, asymmetric, secondary fault current capability.

How do you calculate AC resistance of a transformer?

The AC winding resistance RAC is defined as RAC = Pload/I2 (2.3) According to [1], all of the stray loss is assumed to be winding eddy current loss and winding eddy-current loss for sinusoidal currents is approximately proportional to the square of the frequency.

How do you measure winding resistance?

Touch the red (positive) lead of the multimeter to the positive end of the wire windings around the motor. Touch the black (negative) lead of the multimeter to the negative end of the wire windings around the motor. The reading that appears on the multimeter screen is the resistance in ohms.

What is percentage reactance of a transformer?

Transformer reactance is often specified as a percentage, say 10\%. This is a per unit value expressed as a percentage on the power base of the transformer. Example: A 350 MVA, 230/20 kV transformer has leakage reactance of 10\%.