Topics
Sizing & Selection
Pick the wrong size and your converter won't start your load. Here's the math — and the shortcuts.
The Multiplier Rule
Phoenix converters are sized to the largest single motor in your system, not total connected load. The multiplier depends on the load type:
| Load Type | Multiplier | Example |
|---|---|---|
| Standard motors (easy start) | 2× | 5 HP motor → GP10NL |
| Compressors, pumps (loaded start) | 2.5× | 10 HP compressor → GP25NL |
| Dust collectors, high-inrush fans | 3× | 10 HP collector → GP30NL |
| CNC machines (check drive specs) | 2–3× | Varies by VFD |
Multiple Loads
When running multiple motors simultaneously, size the converter for the largest single motor using the multiplier above — then verify the total running HP doesn't exceed the converter's rated output. Phoenix converters handle motor starting surges from the idler's stored energy, so the largest motor gets the multiplier; smaller motors just add running load.
Voltage Selection
- 230V output: NL or PL series. Use when all your equipment runs on 230V 3-phase.
- 460V output: NLT, PLT, NLTA, or PLTA series. These include a built-in autotransformer. Never use a bare NL for 460V applications.
Quick Reference: Model Selector
| Largest Motor (HP) | Load Type | Recommended Model |
|---|---|---|
| 1–2 HP | Standard | GP3NL / GP5NL |
| 3–5 HP | Standard | GP7NL / GP10NL |
| 5–10 HP | Standard / Compressor | GP15NL / GP20NL |
| 10–15 HP | Standard / Compressor | GP25NL / GP30NL |
| 20–30 HP | Standard / Compressor | GP40NL / GP60NL |
| 40–50 HP | Standard | GP75NL / GP100NL |
For 460V output, substitute NLT for NL above.
Still Not Sure?
Call us at (800) 417-6568 with your motor nameplate HP and load type. Sizing calls take 5 minutes.