Contactor selector

For Worldwide: KKE Circuit is available across Global in English. Region: Global (INT).

Tools

Pick indicative contactor sizes for DOL and star-delta motor starters from motor power, line voltage and coil voltage.

Starter type

Motor power

Power unit

Motor line voltage Power factor

Contactor coil voltage Duty category Efficiency

Recommended selection

Main contactor

—

Delta contactor

—

Star contactor

—

Calculated FLC

— A

Coil

—

Starter

—

How it works

The tool first estimates motor current from power. For three-phase motors, FLC = P / (sqrt(3) x V x pf x efficiency). It then applies practical motor-starter selection rules for AC-3 duty. DOL uses the full motor current with a safety margin. Star-delta uses reduced current ratios for the main, delta and star contactors, then rounds up to the next standard contactor frame.

Important disclaimer

This tool gives an indicative contactor size only. It does not replace a full motor-starter design review, protection coordination, or manufacturer selection table.

Selection note

Motor full-load current is estimated from motor power, voltage, power factor and efficiency.
For DOL, the main contactor is selected at or above motor full-load current with an AC-3 margin. For star-delta, main and delta contactors are selected at about 58% of motor line current, while the star contactor is selected at about 33%.
Final selection must still be checked against making duty, short-circuit coordination, coil supply and manufacturer data.

Inside KKE Circuit

Design the starter, not just one contactor

This selector helps with one motor starter. KKE Circuit lets you design the whole control panel and schematic, keep devices linked, and export the BOM and wire list automatically.

Panel devices linked to schematics

Contactors, overloads, auxiliaries and terminals stay tied to the drawing so changes ripple through the project.

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Motor feeder checks

Combine cable sizing and voltage-drop checks with starter selection inside the same electrical design workflow.

BOM and terminal reports

Generate parts lists, cable schedules and terminal plans from the live project instead of maintaining separate spreadsheets.

Wire numbering and cross references

Keep control wiring, device tags and cross references synchronized across revisions.

IEC and ANSI symbols

Work with the symbol set your customers expect without redrawing the whole project.

Real-time collaboration

Share ownership across engineers with revision history and collaborative browser-based editing.