IS 8544 Pt.3/Sec.1-1979

标准号：IS 8544 Pt.3/Sec.1-1979
发布日期：1979/9/1 12:00:00
实施日期：1999/12/31 12:00:00
适用范围：1.1 This standard ( Part Ill/Sec 1 ) applies to starters for industrial use, designed for starting an ac induction motor having a wound rotor, by cutting out resistor previously inserted in the rotor circuit, and to provide means for the protection of the motor against operating over-loads, and to cause intentionally the motor to stop.1.2 It applies only to starters, the main contacts of which are intended to be connected to supply circuits the rated voltage of which does not exceed 1000 V ac. In the case of asynchronous slip-ring motors ( wound-rotors ), the highest voltage between slip-rings shall be not greater than twice the rated insulation voltage of the switching devices inserted in the rotor circuit ( see 4.4.1.4 ).Note — This easement is based on the fact that the electric stresses are less severe in the rotor than in the stator and are of short duration.1.3 This standard also applies to starters for two directions of rotation when reversal of connections is made with the motor stopped ( see 4.4.6 ). Operations including inching and plugging will necessitate additional requirements and shall be subject to agreement between the manufacturer and the user.1.4 This standard applies to resistors which are part of the starter or constitute a unit specially designed to be associated with the starter.1.5 The starters dealt with in this standard are not designed to interrupt short-circuit currents. Therefore, suitable short-circuit protection [ see Appendix A of IS : 8544 ( Part I )-1977* ] shall form part of the installation, but not necessarily in the starter.The clauses of this standard relating to overload protection may not apply in the case of controlgear associated with built-in over-temperature protective devices.Note — The expression ' built-in ' means ' built into the motor '.1.6 This standard does not apply to:a) unbalanced starters, namely, where the resistances do not have the same value in all phases;b) equipment designed not only for starting, but also for adjustment of speed;c) liquid starters and those of the 《 liquid-vapour 》 types; and d) static starters using semi-conductor elements.