Motor starter configurations
Different configurations of switchgear and control-gear are commonly proposed. Some examples are shown on Figure N66.
Fig. N66: The various functions and their combinations forming a motor starter
The different applicable standards are listed on Figure N67.
| Standard | Title |
| IEC 60947-1 | Low-voltage switchgear and controlgear – General rules |
| IEC 60947-4-1 | Contactors and motor-starters –Electromechanical contactors and motor-starters |
| IEC 60947-4-2 | Contactors and motor-starters – AC semiconductor motor controllers and starters |
| IEC 60947-6-2 | Multiple function equipment – Control and protective switching devices (or equipment) (CPS) |
| IEC 61800 | Adjustable speed electrical power drive systems |
Fig. N67: Applicable standards
Different utilization categories have been defined for contactors in IEC 60947-4-1. The selection relative to asynchronous motor control is given in Figure N68.
| Category | Typical applications |
| AC-1 | Non-inductive or slightly inductive loads, resistance furnaces |
| AC-2 | Slip-ring motors: starting, switching off |
| AC-3 | Squirrel-cage motors: starting, switching off motors during running |
| AC-4 | Squirrel-cage motors: starting, plugging(1), inching(2) |
(1) By plugging is understood stopping or reversing the motor rapidly by reversing motor primary connections while the motor is running.
(2) By inching (jogging) is understood energizing a motor once or repeatedly for short periods to obtain small movements of the driven mechanism
Fig. N68: Different categories of AC contactors used for asynchronous motor control
