2.0×CSCR starting torque
0.3×PSC starting torque
44 Astarting current at 230 V
The duty
A 1.5 kW workshop compressor on a 230 V single-phase supply must restart against residual pressure: it needs well over its running torque from standstill.
Comparing EMPD single-phase designs at 1.5 kW 4-pole
| Design | Starting torque | Starting current | Verdict |
|---|---|---|---|
| CSCR · capacitor start, capacitor run | 2.0 × MN (20 Nm) | 5.1 × 8.7 A = 44 A | Starts under load ✓ |
| PSC · permanent split capacitor | 0.3 × MN (3 Nm) | 4.1 × 8.5 A = 35 A | Fans only ✗ |
Supply and protection
- The 44 A starting current lasts a fraction of a second. A 16 A circuit breaker with a C curve (magnetic trip at 5–10 × rated current) rides through it; a B curve may trip.
- The start capacitor (200 µF) is switched out by a centrifugal switch or relay once the motor runs; the 30 µF run capacitor stays in circuit for efficiency and power factor.
- For 60 Hz markets, EMPD winds the motor and selects capacitors for 60 Hz; a 50 Hz motor must not be run on 60 Hz.
Application study: an engineering example worked by EMPD with catalogue data. Your application is confirmed by our engineers before quotation. Send us your duty.
