Phrantech technologies

uestions & Answers on Batteries & troubleshooting - Part 1

1-List down the applications of auxiliary DC power supply system in Power plants? -Protections relays -Circuit breakers -DCS -Trip circuits -Signaling -Telephone system & communication -Emergency lighting -Transmitters & Positioners -Emergency oil pumps -Metering panels

2-List down the various DC voltages & their applications in power plants 220 VDC & 110 VDC - Protection system / Emergency lighting / Trip & closing coil of circuit breakers / Operating mechanisms . 48 VDC - Telephone communication +/- 24 VDC - Control circuits / Measuring instruments / Static relays

3-What is the power source for DC supply? Main power source is lead-acid storage battery & AC/DC rectifier set

4-What are the installation requirements for lead acid battery ? The room should be isolated from other system Room should have adequate lighting & ventilation The room walls & floor should have acid proof tiles Battery cells should be installed on insulated racks Racks should be placed on insulator generally porcelain insulators Cables should be acid proof The DC bus bars should be of round or flat copper materials Bus bars connections are made by soldering or brazing The positive terminal of the battery is Red & negative terminal should be blue.

5-How do you calculate the maximum discharge current of batteries? Maximum discharge current = (Continuous load (W1) + Short time Load (W2)) / Rated Voltage

6-How do you specify the batteries? -Batteries have following specification: -Rated voltage -No. of cells -AH capacity -Arrangement of cells -Details of charging equipment

7-What do you mean by AH of batteries? AH (Ampere hour) is the capacity of battery. It is the product of current and total time required for discharge. It depends on the magnitude of discharge current.

8-How do you decide the number of batteries for a particular battery bank? No. of battery cells = Bus bar voltage / Voltage of one cell

9-What are the various charging methods employed for batteries? -Initial charging -Quick charging -Trickle charging

10-What do you mean by trickle charging? & what is its significance? Trickle charging is constant charging current that is supplied to battery to compensate its discharge current. Batteries get discharge when not in use. Hence to avoid sulphating, the batteries should be kept continuous charging by trickle charging.

11-What do you mean by primary cells (dry cell) & secondary cells? Primary cells are non rechargeable cells & Secondary cells are storage batteries

12-What are anode, cathode & electrolyte in Lead-acid batteries? Cathode: Sponge lead Anode: Lead Peroxide (PbO2) Electrolyte: Sulphuric acid & water

13-What is the voltage level of lead acid batteries that are generally employed? It is 2 V

14-What is the voltage level of fully charged & fully discharged lead acid battery? Voltage of fully charged cell is 2.5 V & 1.75 V for fully discharged cell

Direct on line