Motor starter configurations

Different configurations of switchgear and control-gear are commonly proposed. Some examples are shown on Figure N66.

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Fig. N66: The various functions and their combinations forming a motor starter

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The different applicable standards are listed on Figure N67.

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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

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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.

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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

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