29 of 124  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 08: Electrical Works  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:  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.  • 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:   Common fault  running  emergency stop activated (if applicable) - Selector switch for hand-off-automatic (HOA) control In position:   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.  - Push buttons for:   LED type start/stop   common fault reset  • Auxiliary contacts for remote monitoring.  8_Vol3_d4 3_Section 8 electrical works_en_GIR rev6.doc 