A 230 V, 1-phase, 60 Hz motor requires a 40 microfarad (µF) start capacitor connected in series with the start winding. If the motor controller is replacing the start capacitor, which characteristic is critical for the new capacitor to ensure proper motor operation and prevent damage?

Question: A 230 V, 1-phase, 60 Hz motor requires a 40 microfarad (µF) start capacitor connected in series with the start winding. If the motor controller is replacing the start capacitor, which characteristic is critical for the new capacitor to ensure proper motor operation and prevent damage?

Answer options:

• Its voltage rating must be at least 230 V AC. ✅ Its voltage rating must be at least 460 V AC.
• Its capacitance must be exactly 40 µF.
• Its capacitance must be between 30 µF and 50 µF.

Correct answer: Its voltage rating must be at least 460 V AC.

Explanation: Start capacitors in single-phase motors often experience transient voltages higher than the AC line voltage (sometimes 2 to 3 times the line voltage) during the starting period. Therefore, the capacitor's voltage rating must be significantly higher than the line voltage, typically at least twice the RMS line voltage, to prevent failure.