How do you calculate the amperage of a transformer?

How do you determine the maximum amps of a transformer?

The full load current I(A) in amps is equal to 1000 times of transformer rating S(kVA) in kVA divided by the multiplication of root 3 times of line to line voltage V(V) in volts.

How many amps is a 25 kVA transformer good for?

Three Phase Transformer

KVA 208V 480V
20 56.6 24.1
25 69.5 30.1
30 83.4 36.1
37.5 104 45.2

How do you calculate the full load current of a transformer?

Transformer Formulas

  1. Single Phase Transformer Full-Load Current (Amps)= kVA × 1000 / V.
  2. Three Phase Transformer Full-Load Current (Amps) = kVA × 1000 / (1.732 × V)
  3. Turns Ratio = N1 / N2 = V1 / V2 = I2 / I1

How do I calculate amperage?

Calculating Amperage

A simple formula for calculating amps is to take the watts and divide that by the volts. So, for instance, if the wattage of the lighting fixture you’re working with is 60 and the volts are 12, divide 60 by 12 and you will get five, which are the amps.

How do you find the current 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.

THIS IS IMPORTANT:  Best answer: Is it good to exercise as soon as you wake up?

What is the transformer formula?

Vp=−NpΔΦΔt V p = − N p Δ Φ Δ t . This is known as the transformer equation, and it simply states that the ratio of the secondary to primary voltages in a transformer equals the ratio of the number of loops in their coils.

How do you calculate the secondary winding of a transformer?

Solve the equation Vs/Vp = Ns/Np where Vs is the secondary voltage, Vp is the primary voltage, Ns is the number of secondary windings and Np is the number of primary windings. Divide the number of secondary windings by the number of primary windings, and multiply the source voltage by this ratio.

How do you find the magnetizing current of a transformer?


  1. Apply rated voltage to the LV side of the transformer.
  2. Measure the no-load current Io, power Po, and input voltage Vo.
  3. Measure the open-circuited HV side voltage if the transformer ratio needs to be calculated.

How do you calculate full load secondary current?

Transformer full load current = kVA / (1.732 x Volt)

  1. Transformer full load current = kVA / (1.732 x Volt)
  2. Transformer full load current = 1000 / (1.73 2× 480) = 1203 Amp.
  3. Short circuit current at TC secondary (Isc) = Transformer full load current / Impedance.