BATTERY BANK AND ITS MAINTENANCE PROCEDURE NEW.pptx

Battery bank and it's maintenance procedures

1. GUIDED BY SHRI M.S KHAN SIR ADDL C.E(O&M-II),1x500MW WELCOMEs SHRI SANJAY SHARMA SIR,E.D(GEN) AND ALL THE CSPGCL OFFICERS S.E .(ET-III)

2. BATTERY AND ITS MAINTENANCE

3. Accessories to be available in battery room For safe Handling:- The various accessories listed below should be readily available in the battery room hydrometer Thermometer of range 0-60C . Cell testing voltmeter 3-0-3 V. Insulated Spanner . Acid resisting jug & funnel. Distilled water as per IS : 1069. Petroleum jelly for covering the exposed metal parts of the battery. Rubber gloves. Rubber aprons. Eye wash bottle/Tap water. Nylon brush with stout bristles or cleaning connections. 5 to 10% Ammonia or Soda solution to neutralize the spot affected by acid splash.

4. BATTERY/CELL :- Battery is basically a combination of cells. IT IS BASED ON PRINCIPLE OF CONVERSION OF CHEMICAL ENERGY IN TO ELECTRICAL ENERGY.

5. TYPES OF CELLS :- Primary Cell :- They are designed to be used once and discarded. They are supplied in fully charged condition. supplies current until the electrolyte is exhausted or the negative electrode is completely dissolved The cell can not be recharged Shell life about 1 year Eg : toys, ac, remote, multimeters etc:-

6. SECONDARY CELLS:- cells that can be charged & discharged in to a load many times. Also known as storage cells There are 2 types of storage cells . One in known as a mobile cells. They move along with the equipment for which it is used eg ;- mobile phones, laptops, drones etc. And the second is stationary cells. They are installed/located at one place and supply is extended to the equipment / system wherever cells located. eg :- Power plant batteries

7. APPLICATION OF SECONDARY CELLS:- These are used in a no of applications such as : Starting , lighting and ignition applications in automobile. Motive power application like the battery operated forklift, trucks, mine locomotives and other material handling equipment's. Providing the necessary standby power to the electrical system for the railway coaches which include lighting, air conditioning and also starting of Diesel Engines in Locomotives . To provide power to submarines whenever the submarine is submerged in water. To provide standby D. C. Power in power stations and substations , thus protecting the extensive switchgears of these stations . To provide standby power in UPS system.

8. SELECTION OF A BATTERY:- Battery is basically selected on the basis on load/current that need to be connected. Battery as we all know is rated in mAH milliampere hour or AH amp hour. The run time of battery /battery capacity dictated by this rating. It is basically the discharge current/load that a battery can provide over time. Eg :- Let us assume a house load of 200W with pf 0.8 for 6 hrs back up. 200/.8=250x6/12V=125 AH similarly for house load of 215A in our power plant for backup of 10 hours minimum 2250 Ah battery must be selected.

9. MOST COMMON TYPE OF RECHARGABLE BATTERY :- LEAD ACCUMULATOR/LEAD ACID :-

10. CHARGING AND DISCHARGING OF BATTERY:- DISCHARGING : i ) Pbo2+H2+H2So4= PbSo4+2H2O ii) Pb+So4=PbSo4 CHARGING : i )PbS04+S04+2H20= Pb02+2H2So4 ii)PbS04+H2= Pb + H2So4

11. CHARGING A NEW BATTERY:- NEW cells or batteries shall be first charged in accordance with the instructions issued by the battery maker . Cells or batteries are normally considered to be fully charged when cell voltage and specific gravity readings are constant over at least 3 Hours, readings being taken hourly.

12. Sp. gravity of electrolyte to be filled-in in new cells be 1.200-1.210. The minimum soaking period to the battery cells shall be 12 to 24 Hr . from the time of filling of electrolyte of sp.gr. 1.205 to the first start of charging the cells. Charging can be initiated by a) starting rate (first portion) up to DEGASSING POINT (2.35V) & followed by finishing rate (Second portion) (2.75V). OR By Finishing rate throughout till completion of charging Maximum temperature of electrolyte during charging be limited to 50 C. maximum. Charging rate be regulated to control cell temperatures within the limit. While charging the new cells the sp. Gravity of electrolyte reduces first and later goes on increasing.

13. Capacity Test /Load Test:- Discharge : - The battery which has given the first charge, is allowed to stand on open circuit for not less than 12 hrs. and not more then 24 Hours. Thereafter discharge the battery at a constant full load current of battery. The discharge shall be stopped. When : a) the closed circuit voltage across the battery has fallen to 1.85 x n volts. Where ‘n’ is the number of cells in series in the battery or. b) When the voltage across any one cell has fallen to 1.85 Volts whichever is earlier. charge:- Recharge the battery at a constant starting current equal to full load Amps till the cells start gassing at a voltage of 2.35 to 2.4 Volts per cell and thereafter reduce the charging current to the finishing rate and continue charging at this current till the voltage of each cell reaches 2.65V to 2.75V and the specific gravity to 1.210 +/- .005 and both remain constant for three consecutive half hourly readings (at the reference temperature of 27C).

14. ASPECTS OF PERIODIC MAINTENANCE :- Daily :- i ) The float voltage of the charger across the battery should be noted at the charger end, as well, as at the battery end. Other parameters like charger output current and voltage must also be checked. ii)The float charger has to be examined to check whether the same is working in “Auto” mode. iii) Electrolyte specific gravities, voltage and temperature of a few chosen cells, called pilot cells have to be taken everyday. 2 out of every 60 cells of the battery bank can be used as pilot cells for daily specific gravity measurements. Pilot cells may be changed every month for monitoring battery condition better.

15. FORTNIGHTLY :- In addition to the Daily Maintenance procedure detailed above, the following additional maintenance has to be done every week : i ) Check the electrolyte level in each of the cells to ensure the electrolyte level to correspond to the red mark on the float/guide on batteries. If the level is lower, top-up with pure battery grade distilled water (IS : 1069). ii) The cell containers, stands, insulators, connectors, vent plugs, terminals etc . have to be cleaned .

16. MONTHLY:- In addition to the Daily and Fortnightly Maintenance procedure, it is necessary to adopt the following procedures, every month :- Check Voltage specific gravity and temperature for all the cells Visually check the condition of each cell and battery bank . Any abnormality observed to be immediately noted and observed for next 15 days. Check electrolyte level in all the cells and note . Plante cells are not expected to show much of a water loss in a month any abnormality cause to be investigated

17. QUARTERLY: In addition to the Daily, Fortnightly & Monthly Maintenance procedure, it is necessary to adopt the following procedures:- Check the electrolyte specific gravity of all the cells to ensure the same to be within 1.200 ± 0.005. If the specific gravity of most of the cells are found to be lagging by an average of 10 to 15 points, battery bank would call for equalizing charge at 3 to 5% of its rated value for 6 to 10 hours to restore the state of full charge.

18. Half Yearly :- In addition to the Previously mentioned maintenance procedure, it is necessary to adopt the following procedures:- Remove all corrosion product and clean thoroughly. Use enough amount of petroleum jelly on connectors

19. Yearly :- In addition to the Previously mentioned maintenance procedure, it is necessary to adopt the following procedures:- This would require matching annual maintenance schedule with annual shutdown . Follow C10 charging & discharging procedure for carrying out load test . The battery bank is to be given an equalizing charge at 3% for 12-16 hours.

20. Battery Trouble Cause Remedies Battery Trouble Symptoms/ Cause Remedies Battery Trouble Symptoms/ Cause Remedies Over charging Excessive gassing Falling of active material from positive plates. Buckling of plates Increased temperature Bulging of container Reduce the charging rate till the specific gravity attains value 1210. Add distilled water. Under charging Low specific gravity Lighter colour of plates Reversal of cell voltage Sulphation on the battery terminals Increase the charging rate till the specific gravity attains value 1210. Clean the battery terminals and links

21. Battery Trouble Cause Remedies Battery Trouble Symptoms/ Cause Remedies Battery Trouble Symptoms/ Cause Remedies Loss of capacity Abnormal drop of voltage during a normal discharge without corresponding rise in temperature due to : 1) Loss of active material from plates 2) Formation of sulphate 3) Loss of electrolyte 4) Some material impurities 1) Contact manufacture for special treatment / repairs. Corrosion of plates Impure electrolyte High rate of charging Remove electrolyte Flush with distilled water Refill with pure electrolyte Reduce the rate of charging

22. Battery Trouble Cause Remedies Battery Trouble Symptoms/ Cause Remedies Battery Trouble Symptoms/ Cause Remedies Fracture & buckling of plates Discharge at too rapid rate Unequal distribution of current over plates Defective plates Plates exposed to direct sun Reduce the charging rate Replace the defective plates Disconnect the cells from service. Shedding of active material Overcharging of plates Charging done at high rate Defective material Material improperly applied on plates Charging and discharging limits should be maintained as per manufacturers recommendations Contact manufacturer for defective material.

23. CAPACIY @10 HRS RATE(AH) STARTING RATE AMPERES FINISHING RATE AMPERES TRICKLE CHARGE MIN( mA ) TRICKLE CHARGE MIN( mA ) 48AH 7 3.5 40 120 100AH 14 7 80 240 200AH 28 14 160 480 600AH 84 42 360 600 1000AH 140 70 600 1200 1250AH 175 87.5 720 1440 2250AH 315 157.5 1250 2500

24. BATTERY CHARGERS:- BREIF DESCRIPTION

25. Battery charger Layout 3P D- Indicates DC Contactor FLOAT CHARGER FLOAT CUM BOOST CHARGER LOAD BATTERY BANK Eg :-220V D

26. Various Operating Modes of Charger:- FLOAT CHARGER FLOAT CUM BOOST CHARGER BATTERY REMARK FLOAT MODE STAND BY MODE FLOAT MODE LOAD IS FED BY THE FLOAT CHARGER FLOAT MODE BOOST MODE BATTERY IN CHARGING MODE LOAD IS TAKEN CARE BY FLOAT CHARGER FAIL FLOAT MODE (BOOST OPERATION IS NOT POSSIBLE) TRICKLE CHARGING IS DONE BY FLOAT CUM BOOST CHARGER LOAD IS TAKEN CARE BY FLOAT CUM BOOST CHARGER FLOAT MODE FAIL/OFF FLOAT MODE LOAD IS FED BY THE FLOAT CHARGER

27. BATTERY CHARGER IMPORTANT PARAMETERS :- Ac input voltage Ac input current Float Voltage Float current Float cum boost voltage Float cum boost current Load voltage Load current Battery voltage Battery charge/discharge current

28. THANK YOU