What size wire do I need to feed a 45 kVA transformer?

What size wire do I need to feed a 45 kVA transformer?

For a 45kVA transformer, 54A×1.25=68A, so use a 4 AWG conductor rated 85A at 75°C, per Table 310.16.

What size wire do I need for a 75 kva transformer?

For example, a 75-kVA, three-phase, delta-delta connected transformer will be installed in an industrial facility. The primary or input voltage will be 480V, and the primary conductors will be 1 AWG THHN conductors.

What is 1 KVA in amps?

1,000 volt-amps

How do you size a transformer wire?

To calculate the secondary conductor size:

1. Determine the primary to secondary voltage ratio: 480V ÷ 120V = 4.
2. Multiply the primary OCPD size by 1/3: 5 × 1/3 = 1.67.
3. Multiply the two values together: 4 × 1.67 = 6.67A.
4. Look in the 60°C, Table 310.16 for the smallest conductor with an ampacity larger than 6.67A.

Is a disconnect required for a transformer?

A disconnect is required to disconnect all transformer ungrounded primary conductors. The disconnect must be located within sight of the transformer, unless the location of the disconnect is field-marked on the transformer and the disconnect is lockable [450.14], as shown in the Figure.

Do you need to ground a transformer?

Transformers themselves are not and do not have to be grounded. Grounding is mostly used for increased safety when it comes to appliances utilizing the mains electricity. You need to be aware though that since by using these transformers you forfit ground protection.

What is the difference between 3 phase 3 wire and 4 wire?

Answer. 3 Phase 3 wire system includes all the phases i.e R Y and B while in 3 phase 4 wire system an additional neutral N is present.

How do you calculate the neutral current in a 3 phase 4 wire system?

If A, B and C are the three phase currents, the formula to find the neutral current is the square root of the following: (A^2 + B^2 + C^2 – AB – AC – BC).

How do you calculate unbalanced current in 3 phase?

Current unbalance can be due to the motor or the supply line. To determine the source, arbitrarily label the supply lines A, B, and C — and the motor leads 1, 2, and 3. Then connect A to 1, B to 2, and C to 3, operate the motor, and measure the current in each line.

How do you calculate 3 phase unbalanced current?

There are three steps in the calculation:

1. Determine the voltage or current average.
2. Calculate the largest voltage or current deviation.
3. Divide the maximum deviation by the average voltage or current and multiply by 100 % unbalance = (Max deviation from average V or I/average V or I) x 100.