A pilot device, such as a push button or limit switch, is used in a motor control circuit. What is the primary function of a pilot device in this context?
- ATo control the operation of another device, such as a motor starter.
- BTo convert AC voltage to DC voltage for motor operation.
- CTo provide overcurrent protection for the motor.
- DTo directly switch the main motor current on and off.
Show answer & explanationAnswer & explanation
Correct answer: A. To control the operation of another device, such as a motor starter.
Pilot devices are low-power control devices that do not directly handle the main motor current. Instead, they send a signal to another control device, such as a motor starter or contactor, which then switches the higher motor current. Their primary function is to control, not to switch power directly or provide protection.
Why the other options are wrong
- B. This is the function of a rectifier or power supply, not a pilot device.
- C. Overcurrent protection is handled by circuit breakers, fuses, or overload relays, not pilot devices.
- D. Pilot devices handle low control current, not the main motor current.
Pilot Device Function
A pilot device is a control circuit component (e.g., push button, limit switch, float switch) that senses a condition or receives an input and then sends a low-power signal to another control device (like a motor starter or relay) to initiate or stop an action, rather than directly controlling the main power circuit.
- Operates in the control circuit, not the power circuit.
- Sends signals to other control devices (e.g., contactors, relays).
- Does not directly switch main motor current.
- Examples include push buttons, limit switches, pressure switches.
Memory trick: Pilot device: a small finger that tells the big hand what to do.