標準號：IS 8544 Pt.2-1977
發布日期：1977/12/1 12:00:00
實施日期：1999/12/31 12:00:00
適用范圍：1.1 This standard ( Part II ) covers star-delta starters for industrial use, intended to start, in the star connection, and accelerate an ac three-phase motor to normal speed and to provide means for the protection of the motor and its associated circuits against operating overloads, and to cause intentionally the motor to stop.It applies only to starters the main contacts of which are intended to be connected to circuits the rated voltage of which does not exceed 1 000 V ac. — In the star connection, the current in the line and the torque of the motor are about one-third of the corresponding values for delta connection. Therefore, star-delta starters are used when the inrush current due to the starting is to be limited, or when the driven machine requires a limited torque for starting. Figure 1 indicates typical curves of starting current, of starting torque of the motor, and of torque of the driven machine.Note 2 — In this standard it is generally assumed that star connection is the transitional position for starting. If for special application the star connection is desired as a normal operating connection, an agreement as to special characteristics required for such application shall be reached between the manufacturer and the purchaser.1.2 This standard does not cover star-delta starters intended for reversing the motors rapidly, that is, involving plugging operation. Moreover, they are not designed to interrupt short-circuit currents. Therefore, suitable short-circuit protection should form part of installation but not necessarily in the starter [ see Appendix C of IS : 8544 ( Part I )-1977* ].1.3 The clauses of this standard relating to overload protection are not applicable to starters operating in conjunction with overtemperature devices built into the motors.1.4 The special requirement for starters intended for use in railways, road vehicles or in aircraft are not covered in this standard.1.5 The starters used in ships shall also comply with any supplementary requirements.1.6 The service conditions for which the starters conforming to this standard are suitable, shall be as given in Appendix B of IS : 8544 ( Part I )-1977*.