What happens to the resistance in the start winding of a motor as it heats up?

What happens to the resistance in the start winding of a motor as it heats up?

• A. It increases rapidly
• B. It remains constant
• C. It decreases rapidly
• D. It fluctuates

Answer: (A)

The start winding of a motor is typically made of copper or aluminum, which are conductive materials. As the motor operates, the start winding generates heat due to electrical resistance. This increase in temperature leads to an increase in the resistance of the winding. Materials like copper have a positive temperature coefficient, meaning that as they heat up, their electrical resistance increases. When the motor starts and the winding heats up, the resistance can rise significantly, which is crucial for the motor's operation since it helps limit the current flowing through the winding once the motor reaches a certain speed and can switch to its run windings. This characteristic is important for the function of the motor, ensuring that once it has started, the start winding is effectively disengaged from the circuit, allowing the motor to operate more efficiently. Other options do not accurately reflect how resistance behaves in relation to temperature changes in this context.

The start winding of a motor is typically made of copper or aluminum, which are conductive materials. As the motor operates, the start winding generates heat due to electrical resistance. This increase in temperature leads to an increase in the resistance of the winding.

Materials like copper have a positive temperature coefficient, meaning that as they heat up, their electrical resistance increases. When the motor starts and the winding heats up, the resistance can rise significantly, which is crucial for the motor's operation since it helps limit the current flowing through the winding once the motor reaches a certain speed and can switch to its run windings.

This characteristic is important for the function of the motor, ensuring that once it has started, the start winding is effectively disengaged from the circuit, allowing the motor to operate more efficiently. Other options do not accurately reflect how resistance behaves in relation to temperature changes in this context.