UL 1004-3:2018 Thermally Protected Motors.
1.1 UL 1004-3 is intended to be read together with the Standard for Rotating Electrical Machines — General Requirements, UL 1004-1. The requirements in this Standard supplement or amend the requirements in UL 1004-1. The requirements of UL 1004-1 apply unless modified by this Standard.
1.2 This Standard applies to motors that rely upon a device (thermal motor protector) to prevent overheating under at least one operating condition. These motors shall be identified as thermally protected motors.
1.3 This Standard applies to motors protected either by electromechanical thermal motor protectors or solid-state thermal motor protectors.
1.4 This Standard applies to impedance protected motors where the manufacturer has provided a supplementary thermal motor protector.
1.5 The requirements in this Standard are intended to evaluate a specific motor/protector combination. When the motor, the protector, or the motor/protector combination is changed, the combination shall be reevaluated.
1.6 This Standard applies to motors provided with coordinated protection where Locked Rotor protection is provided by one means and Running Heating protection is provided by another as required by 7.11.
2.1 For the purpose of this standard, the following definitions apply.
2.2 AUTOMATICALLY RESET PROTECTOR — A device that is calibrated to open the motor circuit upon reaching a certain temperature and automatically closes the circuit once the device has cooled to a lower temperature.
2.3 INTENTIONALLY WEAK TRACE (IWT) — A trace or conductive path provided on a printed-wiring board that is specifically designed to open under overcurrent conditions in order to provide a protective function for circuitry and components.
2.4 MANUALLY RESET PROTECTOR — A device that is calibrated to open the motor circuit upon reaching a certain temperature and requires a manual action to reclose the motor circuit.
2.5 PRIMARY PROTECTOR — A protector that is expected to operate during the abnormal testing of a motor sample.
2.6 SELF-HOLDING PROTECTOR — A device that is calibrated to open the motor circuit upon reaching
a certain temperature but requires both cool down below the calibration point and removal of power for
resetting of the protector.UL 1004-3 pdf download.