- Answer should basically say: “Overload protection prevents an electric motor from drawing too much current, overheating, and literally ‘burning out’.”
- Resting: 0%
Starting: 600-800%
Operating under load: 100%
- Answer should basically say: “A motor is designed to run at a certain speed, called its synchronous speed. If the load on the motor increases, the motor draws more current to continue running at its synchronous speed. It is quite possible to put so much load on a motor that it will draw more and more current without being able to reach synchronous speed. If this happens for a long enough period of time, the motor can melt its insulation and burn out.”
- Answer should basically say: “A fuse or circuit breaker sized to handle the normal running load of the motor will open the circuit during startup. Sizing the fuse or circuit breaker for the spike in current draw would not permit smaller overloads to trip the breakers, and the motor would burn out.”
- Answer should basically say: The eutectic overload relay measures the temperature of the motor by monitoring the amount of current being drawn through a heater coil. The bimetallic overload relay uses a bimetallic strip to apply tension to a spring on a contact. If heat begins to rise, the strip bends, and the spring pulls the contacts apart, breaking the circuit. The solid state overload relay does not actually generate heat to facilitate a trip. Instead, it measures current or a change in resistance. The advantage of this method is that the overload relay doesn't waste energy generating heat.”
- the maximum time in seconds at which the overload relay will trip when the carrying current is at 600% of its current rating
|
