Introduction to Circuit and Motor Protection – MOTOR PROTECTION (2)

To meet the protection requirements of a motor, overload relays provide a time delay to allow or
temporary overcurrent during start up, tripping capability of a motor circuit once a dangerous level of overcurrent has been detected for a period of time, and the means for resetting the circuit.

Overload relays are represented by an S and by the symbol shown in Figure 28. The overloads illustrated in Figure 29 are available for single pole–single phase, double pole–single phase, and three pole–three phase motor circuits. There are two main types of overload relays: mechanical state, operated by a heater element, and solid-state.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: