This Part of the specification applies to rheostatic rotor starters for industrial use intended to start an a.c. induction motor having a wound rotor by cutting out resistors previously inserted in the rotor circuit, to provide means for the protection of the motor against operating overloads, and to cause intentionally the motor to stop.It applies only to starters having main contacts intended for connection to supply circuits of which the rated voltage does not exceed 1000 V a.c. and in the case of asynchronous slip-ring motors (wound rotors), where the highest voltage between slip-rings does not exceed twice the rated insulation voltage of the switching devices inserted in the rotor circuit (see Clause 4.4.2.5).This Part of the specification applies also to starters for two directions of rotation when reversal of connections is made with the motor stopped (see Clause 4.4.7). Operations including inching and plugging will necessitate additional requirements which are subject to agreement between purchaser and manufacturer.This Part applies to resistors which are part of the starter or constitute a unit specially designed to be associated with the starter.The starters dealt with in this Part are not normally designed to interrupt short-circuit currents. Therefore, suitable short-circuit protection should form part of the installation, but not necessarily in the starter (see Appendix C of Part 1).The clauses of this Part relating to overload protection are not applicable to starters operating in conjunction with over-temperature protective devices built into the motors.This Part does not apply to the following equipment:(a) Unbalanced starters, viz where the resistances do not have the same value in all phases.(b) Equipments designed for both starting and the adjustment of speed.(c) Liquid starters and those of the 'liquid-vapour' type.(d) Static starters using semiconductor elements.

Under revision. See DR 94015