Motor thermal overload relay – how to set it and what it means when it trips

What it protects

The thermal relay protects the motor from prolonged overcurrent and overload.

How it is set

The setting is based on the motor's rated current and the actual operating circuit. It is not set arbitrarily.

Why it trips

• Overload.
• Phase loss.
• Low voltage.
• Mechanical jamming.
• Incorrect setting.

What not to do

Do not increase the setting just to prevent it from tripping. The cause of the increased current must be identified.