BANGLADESH POWER DEVELOPMENT BOARD TENDER ... - BPDB

float charge as well as boost charge (with timer).(2) Description of the EquipmentTwo (2) 125 V DC output, 415 V, three phase input, battery chargers withautomatic regulator and filters to maintain the performance. One (1) set for one(1) battery set and other set as standby. The continuous current rating of thebattery chargers shall be determined by the Contractor so as to meet the capacityof related battery.But the continuous current rating of the chargers shall not be less than thefollowing:-125 V battery : 180A(3) Performancea. Constant Voltage CharacteristicThe chargers shall normally have a constant voltage characteristic and shall bedesigned to carry the load current while the battery floats and to replenish thebattery after intermittent discharge. The set voltage shall be adjustable between1.20 V / cell and 1.70 V/cell by means of a potentiometer located inside thecubicle.The DC voltage shall be maintain within plus / minus 1 per cent of the set voltagefor all loads from zero to rated output for any variation of between plus / minus10 percent of the nominal AC input voltage or between 48 and 52 Hz infrequency.The proper voltage adjusting means such as silicon dropper shall be provided tokeep the DC terminal voltage within a permissible range.If there is a prolonged failure or heavy discharge which causes the battery voltageto fall below the pre-set value, the charger shall operate at the maximum currentoutput not exceeding 250 percent of the rated output to restore the voltage to thepre set value. Constant voltage charging shall recommence automatically whenthe battery voltage reaches the pre-set value.The current limit setting shall be adjustable down to 80 percent rated output.c. ControlThe chargers shall be provided with an automatic / manual control selector switchand the facility by which the output voltage can be adjusted when on manualcontrol. On manual control the charger shall be capable of delivering 50 per centof its rated output at 1.55 V / cell to enable charging of the battery when isolatedfrom the DC distribution board.d. Ripple Voltage LimitsWith the battery connected and with any non-destructive load between zero andrated the peak value of the ripple voltage (unweighted) measured across theGhorasal 200 MW to 300 MW Gas Turbine Peaking Power Plant Project (Vol-2 of 3)104