Why the conversion needs the system voltage
Transformer current depends on apparent power, voltage, phase arrangement, and the connection being considered. A kVA value alone is not enough to determine current. The calculation must also identify whether the circuit is single-phase or three-phase and whether the value is primary or secondary current.
For a single-phase circuit, current is commonly related to apparent power and voltage by:
Current (A) = kVA × 1,000 ÷ Voltage (V)
For a balanced three-phase circuit, the line current is commonly related by:
Current (A) = kVA × 1,000 ÷ (√3 × Line Voltage (V))
These formulas are planning relationships. The project engineer must confirm the connection, tap, operating conditions, power factor, harmonics, inrush, protection, and conductor requirements.
Inputs to record
| Input | Why it matters |
|---|---|
| Transformer kVA | Defines the apparent-power base |
| Primary/secondary voltage | Produces different current on each side |
| Phase arrangement | Changes the calculation relationship |
| Load profile | Affects continuous and peak duty |
| Power factor and harmonics | Influence actual current and heating |
| Inrush and motor starting | May require additional transformer margin |
| Protection and cable data | Determines the final installation design |
Do not use a calculator result as a breaker setting, cable size, or short-circuit rating. Those decisions require a coordinated electrical design.
ElectricalCabinet.net can use the transformer and load inputs to route an enquiry to the appropriate transformer, substation, switchgear, or control-panel scope.
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