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Control Transformer VA Sizer

Control power transformer VA per NEC 450: inrush plus sealed burden stepped to a standard CPT size. 5 inputs, 4 outputs with grouped results.

Inputs

Burden

All energized coils, relays, pilot devices held in.

Biggest single pickup: contactor or solenoid inrush.

Coils that can pick up at the same instant.

Voltages

Primary supply voltage.

Control voltage.

Result

Required VA
Waiting for calculation.
Standard CPT size
Waiting for calculation.
Primary current
Waiting for calculation.
Primary OCPD at 125%
Waiting for calculation.
Screening calculation only. Verify against NEC articles cited on the page and the equipment nameplate; the authority having jurisdiction governs.

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Workspace

Keep the assumptions with the result.

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