IEC 60947-4-2 pdf download.Low-voltage switchgear and controlgear – Part 4-2: Contactors and motor-starters – AC semiconductor motor controllers and starters
1 Scope
This standard applies to a.c. semiconductor motor controllers and starters, which may include a series mechanical switching device, intended to be connected to circuits, the rated voltage of which does not exceed 1 000 V a.c. This standard characterizes a.c. semiconductor motor controllers and starters with and without bypass means. AC semiconductor motor controllers and starters dealt with in this standard are not normally designed to interrupt short-circuit currents. Therefore, suitable short-circuit protection (see 8.2.5) should form part of the installation, but not necessarily of the a.c. semiconductor motor controller or starter. In this context, this standard gives requirements for a.c. semiconductor motor controllers and starters associated with separate short-circuit protective devices. This standard does not apply to – continuous operation of a.c. motors at motor speeds other than the normal speed; – semiconductor equipment, including semiconductor IEC 60947-1 :2007) controlling non-motor loads; contactors (see 2.2.1 3 of – electronic a.c. power controllers covered by IEC 601 46 series. Contactors, overload relays and control circuit devices used in a.c. semiconductor motor controllers and starters should comply with the requirements of their relevant product standard. Where mechanical switching devices are used, they should meet the requirements of their own IEC product standard, and the additional requirements of this standard. The object of this standard is to state as follows: – the characteristics of a.c. semiconductor motor controllers and starters and associated equipment; the conditions with which a.c. semiconductor motor controllers and starters comply with reference to a) their operation and behaviour; b) their dielectric properties; c) the degrees of protection provided by their enclosures where applicable; d) their construction;
3 3.1 Terms, definitions, symbols and abbreviations
For the purposes of this document, the terms and definitions of Clause 2 of IEC 60947- 1 :2007, as well as the following terms, definitions, symbol and abbreviations apply.3.3 Terms and definitions concerning a.c. semiconductor motor controllers and starters 3.3.1 semiconductor switching device switching device designed to make and/or break the current in an electric circuit by means of the controlled conductivity of a semiconductor NOTE This definition differs from IEC 60050-441 :1 984, 441 -1 4-03 since a semiconductor switching device is also designed for breaking the current. [IEC 60947-1 :2007, 2.2.3] 3.3.2 a.c. semiconductor motor controller semiconductor switching device that provides the starting function for an a.c. motor and an OFF-state NOTE 1 Because dangerous levels of leakage currents can exist in a semiconductor motor controller in the OFF- state, the load terminals should be considered as live parts at all times. NOTE 2 In a circuit where the current passes through zero (alternately or otherwise), the effect of “not making” the current following such a zero value is equivalent to breaking the current. 3.3.3 semiconductor motor controller (form 1) a.c. semiconductor motor controller, in which the starting function may comprise any starting method specified by the manufacturer, and that provides control functions which may include any combination of manoeuvring, controlled acceleration, running or controlled deceleration of an a.c. motor. A FULL-ON state may also be provided NOTE See Figure 1 and Table 1 . 3.3.4 semiconductor soft-start motor controller (form 2) special form of a.c. semiconductor motor controller, in which the starting function is limited to a voltage and/or current ramp which may include controlled acceleration, and where the additional control function is limited to providing FULL-ON NOTE See Figure 1 and Table 1 . 3.3.5 semiconductor direct on line (DOL) motor controller (form 3) special form of a.c. semiconductor motor controller, in which the starting function is limited to a full-voltage, unramped starting method only, and where the additional control function is limited to providing FULL-ON NOTE See Figure 1 and Table 1 . 3.3.6 semiconductor motor starter (form 1, form 2, form 3) a.c. semiconductor motor controller with suitable overload protection, rated as a unit NOTE See Figure 1 and Table 1 .
IEC 60947-4-2 pdf download
