Choosing an industrial isolation transformer is not simply a matter of adding up equipment nameplate wattages. A transformer that is too small may overheat, experience excessive voltage drop, trip protective devices, or fail to start connected machinery. An unnecessarily large transformer costs more, occupies more space, and may operate inefficiently under light loads.The correct selection starts with the primary voltage, secondary voltage, phase configuration, load current, and apparent power in kVA. The transformer must then be checked against motor starting current, nonlinear loads, harmonics, duty cycle, ambient conditions, voltage regulation, and future expansion.
