Which device is used to protect the pump motor from overload during starts?

• A. Thermal overload relays
• B. Circuit breakers
• C. Fuses
• D. Soft starters

Answer: (A)

Thermal overload relays are used to protect a pump motor from overload during starts. They monitor the motor windings’ temperature (often via current and a heat-sensitive element) and will trip the control circuit if the motor overheats or stalls, preventing damage from excessive current. They’re typically integrated with the motor starter so the motor stops automatically and can reset after cooling.

Circuit breakers protect the electrical circuit from short circuits and general overcurrent conditions, but they aren’t tuned to protect the motor specifically from startup overheating. Fuses provide overcurrent protection but are single-use and don’t actively protect the motor during repeated starts. Soft starters limit inrush and control acceleration, reducing stress on the motor during start, but they don’t inherently sense winding temperature or provide thermal trip protection.