The Use Case

A cold‑storage facility needs to power a 10 horsepower walk‑in freezer that runs on three‑phase voltage. The building only has single‑phase 120/240 V service available. Reliable, balanced power is essential to keep the freezer’s compressor running continuously without tripping or overheating.

What Usually Matters for Sizing

  1. Horsepower rating – Verify the freezer’s compressor HP (10 HP).
  2. Locked‑Rotor Amps (LRA) / Full‑Load Amps (FLA) – These values are printed on the compressor nameplate and dictate the minimum AutoLink capacity.
  3. Voltage & phase – Determine whether the compressor is rated for 240 V or 480 V three‑phase; the converter must match that voltage.
  4. Starting behavior – Freezer compressors have high inrush currents; an AutoLink (compressor‑duty) converter with built‑in start capacitors smooths the start and protects the motor.
  5. Continuous operation factor – Walk‑in freezers often run 24/7, so apply a 125 % safety margin per NEC.

Common Mistakes to Avoid

  • Using a bare NL or PL converter – Those lack the start‑capacitor bank needed for compressor loads and can cause voltage sag.
  • Ignoring LRA/FLA – Sizing only by HP may lead to an undersized unit that stalls during start‑up.
  • Assuming 240 V single‑phase can directly feed a 480 V motor – If the freezer requires 480 V three‑phase, a transformer package is required.
  • Skipping nameplate verification – The compressor’s exact voltage and LRA must be captured before selection.

Practical Phoenix Recommendation

For this application, Phoenix recommends the gp10mla AutoLink (compressor‑duty) dual‑zone rotary phase converter. This model provides:

  • Balanced three‑phase output at the required voltage (typically 240 V).
  • Integrated start‑capacitor bank sized for a 10 HP compressor’s LRA, ensuring smooth starts and stable running voltage.
  • Dual‑zone design that keeps all legs within ±5 % tolerance, protecting the freezer’s motor life.

If the freezer is rated for 480 V three‑phase, pair the gp10mla with a 230 V to 480 V step‑up transformer package to meet the voltage requirement while still delivering AutoLink protection.

Final sizing must be cross‑checked against the compressor nameplate horsepower, LRA/FLA, voltage, and continuous duty expectations before confirming the order.

What to Have Ready Before Calling

  1. Compressor nameplate HP (10 HP).
  2. Locked‑Rotor Amps (LRA) and Full‑Load Amps (FLA) values.
  3. Required three‑phase voltage – 240 V or 480 V.
  4. Available single‑phase service details – voltage, breaker size.
  5. Operating schedule – continuous vs. intermittent run time.

Providing this data will let Phoenix engineers verify that the gp10mla meets your walk‑in freezer’s power needs and deliver a reliable solution quickly.