AS 1023.2-1989

Specifies requirements for five types of device or relay to protect a.c. electric motors from overtemperature damage caused by overload, phase failure or stalled drive, by sensing the magnitude, duration and, depending on the type, other properties of motor currents.

This Standard applies to current-sensing devices or relays as classified in Clause 1.5 according to their function(s) for the protection of a.c. electric motors.NOTE:1. When used in motor starters, these devices are also required to comply with the relevant requirements of the AS 1202 series of Standards.2. In this Standard the term motor protection relay has a different meaning to that in the previous edition, see Clause 1.4.2.This Standard covers requirements for protection of the motor against-overload; phase failure; and stalled drive.NOTE: A specific device complying with this Standard may not provide phase failure or stalled drive protection.In addition, such devices may provide the following features which are outside the scope of this Standard: (a) Remote temperature sensing input(s).(b) Protection of the motor against other conditions such as-earth fault; phase current imbalance; phase-sequence reversal; and short-circuit.NOTE: Such short-circuit protection is distinct from protection of circuit wiring afforded by circuit-breakers or fuses.This Standard does not apply to the following types of motor overload protection device: (i) Devices operated wholly by the temperature of the frame or windings of a motor.(ii) Devices operated partly by the temperature of the frame or windings of the motor, as covered by AS 1023.3.(iii) Thermally operated, self-resetting devices of the type used in refrigerating units.(iv) Devices built into motor-operated appliances.