Two auxiliary contacts shall be provided for signalling. Single phase failure shall be incorporated on all phases with a sensitivity not exceeding the values stated in EN 60947. 

Contactors for motor starters are to comply with IEC 158 and be arranged as necessary for direct-on-line, with the choice of contactor ensuring that the full-load current is not at the contactors capacity (25% spare capacity is to be assured). Contactors shall be of the no volt release type. Two auxiliary contacts are to be provided for signalling. 

Motor starters shall include the following: 

• Motor circuit breaker, suitably rated moulded case circuit breaker, with short circuit protection. 

• Suitably rated miniature circuit breaker for the control circuit. 

• Contactor suitably rated for direct on line start. 

• Adjustable thermal overload protection 

• Complete control circuit. 

• Set of main and auxiliary terminals and a 15% spare capacity. 

• Door mounted: 

- Indicating lamps for: 

- Selector switch for hand-off-automatic (HOA) control In position: 

 Common fault 

 running 

 emergency stop activated (if applicable) 

 Hand: The operator controls operation of the motor by means of start/stop push buttons. The automatic control system is bypassed. 

 Off: The motor is switched off and inoperative. The automatic control system is bypassed. 

 Automatic (Auto): The motor is controlled by the automatic control system, i.e. the PLC. The start/stop push buttons are inoperative. 

• Auxiliary contacts for remote monitoring. 

- Push buttons for: 

 LED type start/stop 

 common fault reset 

All available signals shall be provided for telemetry and wired to the PLC for remote control and monitoring. 

Circuits for manual operation shall be hardwired to ensure operation of the plant if the automatic control system fails. 

Every safety and protection device for the motor e.g., thermistor switch imbedded in motor windings etc., shall be hardwired into the motor control circuit to ensure immediately disconnection of the motor in the event of a failure.  Important : The control circuit shall be designed such that a tripped motor cannot re-start automatically, but only after the fault has been cleared and after reset by hand via a door mounted push button. 

All available signals shall be provided for communication to the PLC for remote control and monitoring. 

