Overloads
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.
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.
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