Description
This tool calculates the running and starting capacitor values needed to operate a three-phase induction motor on single-phase power. Suitable for small motors (< 1.5 kW), with output power reduced to 60–70%.
Input motor rated power, single-phase voltage, and frequency to automatically calculate:
- Running capacitor (μF)
- Starting capacitor (μF)
- Supports kW and hp units
- Real-time bidirectional calculation
Key Formulas
Running Capacitor: C_run = (2800 × P) / (V² × f)
Starting Capacitor: C_start = 2.5 × C_run
Where:
P: Motor power (kW)
V: Single-phase voltage (V)
f: Frequency (Hz)
Example Calculations
Example 1:
1.1 kW motor, 230 V, 50 Hz →
C_run = (2800 × 1.1) / (230² × 50) ≈ 11.65 μF
C_start = 2.5 × 11.65 ≈ 29.1 μF
Example 2:
0.75 kW motor, 110 V, 60 Hz →
C_run = (2800 × 0.75) / (110² × 60) ≈ 2.9 μF
C_start = 2.5 × 2.9 ≈ 7.25 μF
Important Notes
- Only suitable for small motors (< 1.5 kW)
- Output power drops to 60–70% of original
- Use capacitors rated at 400V AC or higher
- Starting capacitor must be automatically disconnected
- Motor should be connected in "Y" configuration