how to calculate full load current for transformer 3 phase

description in English for how to calculate the full load current of a three-phase transformer:

Full Load Current Calculation for a Three-Phase Transformer:

To calculate the full load current of a three-phase transformer, we use the following standard formula:

Full Load Current (A) = (Transformer Rating in kVA × 1000) / (√3 × Line Voltage in Volts)

Where:

Transformer Rating is given in kVA (kilovolt-amperes)

Line Voltage is the line-to-line voltage (in volts)

√3 (1.732) is used because it’s a three-phase system

Step-by-Step Process:

Identify the transformer rating (in kVA).

Know the line voltage of the system (usually 400V for LT, or 11kV/33kV for HT).

Apply the formula to find full load current in amperes (A).

Example:

Let’s calculate full load current for a 100 kVA, 400 V transformer:

Full Load Current = (100 × 1000) / (1.732 × 400)
= 100000 / 692.8
= 144.3 A

So, the full load current is approximately 144.3 amps.

Note:

Always consider both primary and secondary side voltages if you need current for both sides.

This formula gives the line current, which is used for sizing cables, breakers, etc.

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