Question by akfishes4life: How does a magnetic motor starter work? ?
I was wondering what are the step by step process of the motor starter when current is going through it. If you can give me a website that would be great too. Thanks
Best answer:
Answer by B-Notable
A motor starter is for the purpose of protecting a motor that has no thermal overload protection in the motor itself. Motor starters are typically for 3 phase larger motors. The starter consists of two devices, a contactor that completes the circuit to the motor and an overload relay that monitors the current the motor is drawing. The overload relay can be either thermal or electronic. The thermal type uses a device installed on the overload relay called a “heater” this is a bi-metal element that each leg of the motor goes through and comes in different ratings based on the full load amperage of the motor. While the motor is running the current flows through the heater, if the current draw of the motor exceeds the rating of the heater, the heater element heats up and causes the relay to “trip” which interrupts the contactor coil circuit and de-energizes the contactor. The electronic type of overload relay monitors the current of the motor through inductive current transformers. Each leg of the motor passes through a current transformer built into the overload relay where an electronic circuit monitors the current draw of the motor and trips the relay if the motor draws more than the amperage setting of the adjustable dial on the relay which is set to the full load amperage of the motor. Electronic overload relays are much more sensitive and can protect motors much more effectively than bi-metal overload relays.
These are the most common types of starters although there are motor starters that reduce starting current and or voltage for “soft starts” as well thermal protection. There are also many different application specific starters as well.
I hope this has anwered your question.
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