5 HP Phase Converter for a 2 HP Bridgeport Mill
A 5 HP rotary phase converter is the right choice for a 2 HP Bridgeport vertical milling machine on single-phase power.
Why 5 HP for a 2 HP Mill?
Bridgeport mills are a medium-to-hard starting load. Spindle motor, coolant pump, and power feed all draw current at startup. Using Phoenix sizing rules: 2 HP x 2.0 hard load multiplier = 4 HP minimum. Next available size: GP5NL.
The GP5NL provides the startup torque for full-speed operation without voltage sag or nuisance breaker trips.
Can a 3 HP Converter Work?
A GP3NL may start a lightly loaded 2 HP Bridgeport, but you risk sluggish starts and tripping under combined spindle and power feed load. The GP5NL is the safe choice — and the price difference is modest.
GP5NL Specs
| HP | 5 HP |
| Input | 230V Single-Phase |
| Output | 230V Three-Phase |
| Start Type | NL Auto-Start |
| Warranty | Lifetime |
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Bridgeport Phase Converter — FAQ
Can I run a Bridgeport Series 1 on a phase converter?
Yes — the Bridgeport Series 1 with a 1.5 or 2 HP spindle runs well on a GP5NL. Thousands of Bridgeport mills run on Phoenix Phase Converters.
What about the Bridgeport Series 2 or larger head?
The Series 2 typically has a 3–5 HP head. Size accordingly: 3 HP x 2.0 = GP5NL minimum; 5 HP x 2.0 = GP10NL.
Will the power feed and coolant pump cause problems?
No — the GP5NL is sized with enough headroom to handle spindle motor + power feed + coolant pump simultaneously without voltage sag.
Related Articles
- How to Size a Rotary Phase Converter
- What Is a Rotary Phase Converter?
- Rotary vs Digital Phase Converters
- Phase Converter FAQ
Questions? Talk to an engineer.
Free sizing help. Made in Phoenix, AZ. Lifetime warranty on every unit.
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