GENERATOR SET CONTROL BOARD AND GENERATOR SET CONTROLLERS

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14.1 GENERATOR SET CONTROL BOARD
A generator set control board housing generator set controllers, control switches and buttons, relays, timers, indicating lights, indicating instruments, selector switches, alarms, etc. shall be supplied and installed. The control board shall be cubicle construction suitable for floor standing fabricated from sheet steel of not less than 2 mm thickness of similar construction as for the generator set switchboard as described hereinafter. The construction of the generator set control board shall be as described in the relevant sections of the specification – Specification for Low Voltage Internal Electrical Installation. Whether or not shown in the Drawings, the generator set control board shall be of stand-alone type, not forming part of the generator set switchboard but having the same dimensions in height, depth and section width as that of the generator set switchboard. For parallel operation, the generator set control board shall complete with combined synchroscope and synchronising check relays, dual frequency meter and dual voltmeter. Neutral switch shall be provided in the generator set switchboard for each generator set. The neutral switch shall be capable for carrying for three (3) second the prospective earth fault current available when two numbers or more of generator sets are running in parallel. Auxiliary contacts shall be derived to give an indication of the position of each neutral switch (open / trip / close status). The neutral switches shall be so arranged and interlocked to ensure that only one generator set can be earthed at any one time when the generator sets are running in parallel A common alarm bell of 250 mm diameter and a self-latching mushroom head type EMERGENCY STOP push-button shall be provided at the generator set control board. All control wiring shall be not less than 1.5 sq. mm section insulated with pvc and shall be properly labelled with number sleeves.

 

14.2 GENERATOR SET CONTROLLERS
The generator set control board shall house generator set controllers complete with their function keys, switches and indications. The generator set controllers shall be of microprocessor based type compliance to MS IEC 60950-1, operating at 10 – 40 Vdc suitable for mains input and alternator input of 50 – 275 Vac phase-neutral. The power consumption of the controllers shall be less than 10 W, operating temperature up to 70 0C and relative humidity up to 95 %. All no-voltage contacts shall be rated minimum at 16 A. The controllers shall provide with protection against over-voltage and reverse polarity. The controllers shall also compliance to BS EN 50081-2 and BS EN 50082-2 on electromagnetic compatibility on emission and immunity standards respectively. The controllers shall include the generator set monitoring, protection and control module required for all protective devices for the generator set to suit the generator set operation mode as described in Section 11.0 – Engine Protective Devices. The generator set monitoring, protection and control module shall have expansion capabilities, if so required by the S.O.’s Representative, to meet more monitoring, protection and control functions. All alarm and operation status indication shall be of high visibility LED (light emitting diode) type and/or LCD (liquid crystal display) display board or screen. The parameter settings for the controllers can be configured on the controller itself without using PC (personal computer) to uploading the parameters via communication port. The controllers shall have event capture/logging facilities to record minimum 25 events of alarm and shut-down operation of the protective devices. Each event (date, time, type of fault) can be displayed on the LCD display board. If specified, the events can also be downloaded to the handheld and/or remote PC via a communication port described hereinafter. The controllers shall be of front panel flush mounting type of IP 54 and all cable terminations shall be of IP2X.

 

If specified elsewhere where the controllers are required for full system integration into the building automation system and/or building management system, the controllers shall allow full telemetry facilities with integrated software to be able to parameter checking and setting, status monitoring and controlling, event logging and downloading using PC. Serial communication shall be of Mod-bus protocol and the communication port shall be of RS232/RS485. Communication software of MS-Window based shall be provided. If further specified elsewhere, a comprehensive remote communication via RS232 port with RS232 modem link to either PSTN (public switched telephone network) line or GSM (global system of mobile communication) network shall be provided. In the event of the controllers detecting an alarm condition, it will initiate a modem dial out to the host PC and/or to send text messages to the cell phone to inform and indicate the generator set site and alarm condition, the time and date of occurrence. The generator set controllers shall consist of one or combination of, as the case may be, the following monitoring, protection and control modules to serve their functions as specified in the Bill of Quantities and/or Drawings for the generator set operation modes as described hereinafter:-

(a) Generator set monitoring, protection and control module;
(b) Automatic mains failure module;
(c) Automatic transfer switching module;
(d) Automatic synchronisation and parallel operation module;
(e) Automatic load sharing, balancing and transfer power management module;
Automatic synchronisation and parallel operation module shall complete with digital synchroscope.

 

14.2.1 CONTINUOUS OPERATION MODE
In continuous operation mode, the generator set is to provide continuous supply to the loads. The generator set controllers shall equip with the monitoring, protection and control module and any other associated modules necessary to provide the minimum operation mode described hereafter.
(1) OFF
In this mode the generator set cannot be started.
(2) START
By pressing push-button START, the generator is started. This push-button has to be pressed until the start-up speed is reached.
(3) STOP
By pressing push-button STOP, the generator is stopped immediately. The STOP command remains active throughout the stopping time.
(4) ALARM SILENCE
By pressing this push-button, the alarm signal is switched off. All warning and automatic shut-down functions of the protective devices are indicated by this alarm signal and flashing indications. All flashing alarm indications are indicated by continuous light after push-button ALARM SILENCE has been pressed. After 5 minutes, the alarm signal is switched off automatically.
(5) RESET / LAMP TEST
By this push-button all alarms as well as faults which have caused failure indication are reset. Warning and shut-down alarms which are still active cannot be reset. If this push-button is pressed continuously, test of all indication lamps is initiated.  The controllers shall also able to be configured to receive EMERGENCY STOP signals to stop the generator set. Self-latching mushroom head type EMERGENCY STOP push-buttons shall be provided – one to be provided at the generator set control board and another one in the vicinity of the generator set to be decided on site by the S.O.’s Representative.

 

14.2.2 STANDBY OPERATION MODE
The generator set installed in a standby operation mode is to provide readily and immediate alternative supply to the loads in the event the normal supply from the Licensee or Supply Authority (hereinafter as “mains”) fails. The generator set controllers shall equip with

(a) generator set monitoring, protection and control module,

(b) automatic mains failure module,

(c) automatic transfer switching module and any other associated modules necessary to provide the minimum operation mode described hereafter.

 

(1) AUTOMATIC mode
When mode AUTOMATIC is selected, the automatic emergency operation of the generator set is activated, and this places the generator set in its normal standby mode. In case of mains fails or the mains voltage falls below 15% of the rated voltage, the generator set is started automatically. After the speed and voltage of the generator set are within the normal limits, automatic changeover shall then take place whereby the loads are connected to the generator set. When the mains is restored, the loads are changed over to the mains automatically. Thereafter the loads are supplied by the mains again. After a certain pre-set time, the generator set is stopped.

Time durations for each operation shall be as following:-
a timer (t1) – adjustable up to 15 seconds for starting the generator set;
a timer (t2) – adjustable up to 60 seconds for load connection to the generator set after starting up the generator set;
a timer (t3) – adjustable up to 5 minutes before the automatic load transfer to the mains after mains restoration;
a timer (t4) – adjustable up to 10 minutes for shutting down the generator set after load connection to the mains on mains restoration. All timers shall have calibrated scales in seconds or minutes as appropriate.
(2) TEST mode
In this mode no-load and load test run of the generator set is possible. In mode TEST the generator set is automatically started and supervised without actually changing over the load from the mains to the generator set. However if mains fails during TEST mode, the mains emergency operation is initiated automatically and load connection to the generator set must operate.
(3) OFF mode
In this mode the generator set cannot be started.
(4) MANUAL mode
In this MANUAL mode, the manual operation of the generator set is selected. In this operational mode, the generator does not react to mains failure. The generator set can only be started manually. The generator set can be started manually by push button START and stopped by push-button STOP. The controller shall also incorporate the following key functions in the form of push-buttons:
(1) START

By pressing push-button START, the generator is started. This push-button is only activated in MANUAL operational mode and has to be pressed until the start-up speed is reached.
(2) STOP
By pressing push-button STOP, the generator is stopped immediately. The STOP push-button has precedence over the START push-button and is only activated in MANUAL operational mode. The STOP command remains active throughout the stopping time.
(3) ALARM SILENCE
By pressing this push-button, the alarm signal is switched off. All warning and automatic shut-down function of the protective devices are indicated by this alarm signal and flashing indications. All flashing alarm indications are indicated by continuous light after push-button ALARM SILENCE has been pressed. After 5 minutes, the alarm signal is switched off automatically.
(4) RESET / LAMP TEST
By this push-button all alarms as well as faults which have caused failure indication are reset. Warning and shut-down alarms which are still active cannot be reset. If this push-button is pressed continuously, test of all indication lamps is initiated. The controllers shall also able to be configured to receive EMERGENCY STOP signals to stop the generator set. Self-latching mushroom head type EMERGENCY STOP push-buttons shall be provided; one to be provided at the generator set control board and another one in the vicinity of the generator set to be decided on site:
14.2.3 PARALLEL OPERATION MODE
In parallel operation mode, two or more generator sets are installed to provide either supply to the loads continuously (continuous operation mode) or as the alternative supply to the loads in the event the normal mains supply fails (standby operation mode), as the case may be, as specified in the Bill of Quantities and/or Drawings.

The generator set controllers for continuous operation mode shall equip with

(a) generator set monitoring, protection and control modules,

(b) automatic synchronisation and parallel operation module

(c) automatic load sharing, balancing and transfer power management module. For standby operation mode, the controllers, in addition to the modules required for continuous operation mode, shall equip with

(i) automatic mains failure module and

(ii) automatic transfer switching module.

Automatic active and reactive load sharing, frequency and voltage adjustments between the generator sets shall also be included. The controllers for parallel operation mode shall also provide for programming the selection, sequential starting-up, synchronizing, sharing the load, automatic duty cyclic operation and stopping of the generator sets. Generator set can also be selected to operate singly in the event the other generator set is out of service. The controllers shall complete with any other associated modules for the minimum operation modes described hereafter. In continuous operation mode, the pre-selected lead generator set shall start manually and then follow by the second generator set and other generator sets in sequence automatically. However if in standby operation mode the lead generator set shall start automatically upon failure of the supply from the Licensee or Supply Authority. The generator sets are synchronised to run in parallel, automatically or manually as predetermined, with the closing of the generator circuit breakers. When the generator sets are running in stable conditions, the main generator supply circuit breaker is then closed, automatically or manually as predetermined, to provide electrical supply to the loads.
After the loads are connected, the active and reactive loads shall be shared automatically between the generator sets. At pre-set loading conditions, automatic load transfer shall take place where full load shall be transferred to the selected lead generator set. After the full load is transferred to the selected lead generator and the generator sets are running in stable conditions, the second generator set shall automatically shut down after the predetermined time. In the event the load increases and reaches the pre-set value, the second generator set shall start-up, synchronise and share the loads automatically. For a pre-set condition, the lead generator set is allowed to run continuously for a set time (after 8 hours operation). Thereafter, the second generator set shall automatically start up, synchronise with the lead generator set and share the load. Full load shall then be transferred to the second generator set. The lead generator set shall automatically stop at predetermined time. Vice versa operation shall take place after a set cycle time.

In the case of continuous operation mode, when STOP command is activated, the generator set circuit breakers shall open and the generator sets shall shut-down in sequence automatically. In the case of standby operation mode, the generator sets shall shut-down in sequence automatically after load connection to the mains on restoration of the supply from the Licensee or Supply Authority. In both operation modes, when EMERGENCY STOP command is activated, the main generator set supply circuit breaker and the respective generator set circuit breakers shall open and the generator sets shall shut-down instantly. The neutral switch of the selected lead generator set which is brought to service shall be closed automatically. If the duty neutral switch opens inadvertently, the second neutral switch shall automatically be closed. All interlocks, either electrically or mechanically or both, shall be provided. The selection switches for operational requirements and interlock of the circuit breakers and neutral switches shall be expressed in a truth table which shall be submitted to S.O’s Representative for approval. Operation of the switches and circuit breakers in accordance to the approved truth table shall be verified in the presence of the S.O’s Representative during testing and commissioning at site.


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