BATTERIES
• What are the disadvantages of the maintenance free battery?
The life of battery is only five years.
The state of charge of a battery not knowing by the specific gravity of a battery. We
can know by voltage only.
• What are the problems of hydrogen concentration?
If the concentration of hydrogen more than 4% and less than 74% explosion
problems will be there. Therefore the concentration of hydrogen is restricted to less
than 1% by air changer ventilation system.
• Why lead acid battery requires so much large initial charging?
Initially for a new battery, negative plate will be PbO instead of Pb. To convert all of
them back to Pb, we need so much prolonged initial charging.
• What are the protections adopted in UPS or PMCC supply?
LV (incomer) or UPS input
CTZM, Over current, Short circuit protections
PMCC S or T input or UPS output
Under voltage (27), 51RYB, 51N protections.
• Write chemical equation for lead acid cell.
PbO2 + H2 SO4 PbSO4 +2 H2 (during discharge)
Pb + SO4 PbSO4 (during charge)
• Is the chemical reaction of plante cells same as tubular lead acid cells?
No. Plante cells having both electrodes are lead (Pb) only.
During charging, H2O H2 + O2
O2 react with Pb to form PbO2 + (+ve plate)
During discharge, Pb + c PbSO4 (on -ve plate)
While PbO2 Pb + O2 (on +ve plate).
That is converted back to lead.
Therefore PbSO4 formed only on -ve plate. That is sulphation problem are reduced
by 50%
• What are the advantages of plante type batteries?
Plante plate type batteries have longer life and can with stand rapid discharge.
• Why battery room should be located separately in a power station?
Possibility of battery explosion
Corrosive atmosphere by acid spray.
Fire hazard.
• What are the disadvantages of nickel cadmium battery?
Status of charge not known
Number of cells are more
Cost very high
Environmental protection agency considers cadmium as a hazardous material,
difficult to discard at the end of life.
• What are the effects of temperature in lead acid battery?
Higher electrolyte temp - ah capacity increases but life reduces.
Lower electrolytic temp - ah capacity reduces since chemical reaction rate reduces.
• Why ventilation is essential for Ni-Cad also?
Gases evolved H2 O2 can form explosive mixture.
• How H2 O2 generated in lead acid battery?
At end of charge, when most of the Pb is converted. H2 O2 generated from H2O. O2
appears as gas at positive plate. H2 at negative plate, i.e. gassing starts.
• Why current reduced after gassing?
Excessive gassing shortens the life of battery by scouring the active materials at the
surface of the plates.
• Why aged battery consumes more water?
As aging increases, antimony migrates to negative plate secondary cell reaction.
Therefore more charging current require more water consumption.
• What happens after aging?
Shedding of active material during charging.
Shedding increases with overcharging, heavy discharge, batteries short ckt.
• What is the other effect of low temperature?
When specific gravity decreases, acid freezing point increases, soon reached at low
temperature, volume increases container cracks.
• Why temperature correction required?
As temperature increases, specific gravity decreases. The hydrometer immersion is
more, showing lower readings. Therefore 10ºC raises, 7 points to be added,
corrected to get 27 ºC reading.
• What is meant by sulphation of the cell?
During the discharge lead sulphate is produced and during the charging the same is
converted back into lead and lead peroxide. If the cell is left under charged, lead
sulphate would form which will not reverse back into lead and lead peroxide during
charging. Due to this the cell will loose its original capacity.
• What you meant by shedding?
During the charging and discharging the active materials will undergo volumetric
changes. Due to this some of the material may not be retained with the parent
material and will shed and collected at the bottom of the container. This loss of
active material is called shedding. Due to this the cell will loose its capacity.
• Acid should be poured to water. Why is it so?
When acid and water is mixed lot of heat is generated. Hence there is chances of
splashing of the liquid. If water is poured to acid will splash causing injuries. In the
other case splashing will be of water with concentration of acid, which will not
hazardous as the other one.
• What types of lighting fittings are used in the battery room?
Flame proof acid resistant
• Why ungrounded 250V DC system adopted in our system?
The 250V DC system is feeding to some of the vital loads such as breaker control
etc. Even if one ground has occurred then also these controls should be available.
Continuous monitoring of ground current is employed to eliminate the by passing of
logic due to double ground.
• Why battery capacity limits to 20 minute?
Battery cost is more.
It is better to restore class 3 faster by DG set then putting large battery.
20 min, is enough to shutdown the unit safely.
• What are the main parts of lead acid battery?
a. Container
b. Lead dioxide positive plates
c. Lead negative plates
d. Post strap and seal assemble
e. Separators and retainers
f. Sulphuric acid electrolyte
g. Inter cell connector (lead plated copper)
• What are the different types of charging?
(Normally always) Float charging – 2.15V per cell
It maintains the battery fully charged condition during standby operation by
delivering a small amount of current to cancel the effect of battery natural selfdischarge.
Equalizing charging (2.7V/cell) once in 3 months
Recharge a battery capacity through recovering all useable active materials in the
cell plates.
Boost charging
Boost charging is a quick charging process, which is generally required, if the battery
is drained to a large extent.
• What is the double sulphate reaction?
Pb O2 + Pb + 2H2 SO4 ↔ 2PbSO4 +2H2O
During charging oxygen at positive plate and hydrogen at negative plate are
releasing.
• What are the effects of over charging?
Gassing
Heating
Loosening of plate active material
• What you mean by Drooping characteristics of charger?
When the charger is connected to excess load of charger rating the charger should
able to supply the load with out over loaded by maintaining the terminal voltage
within limit without over load trip. This called a drooping output voltage
characteristics.
• What are the effects of under charging?
Sulphation
Buckling of plates
• What are the effects of high temperature?
Gassing of electrolyte and evaporation
Service life is halved for every 8 deg increase above 25 deg.
• What are the effects of low temperature?
Increased electrolyte viscosity.
• What type of thermometer is used for acid batteries?
Alcohol type thermometer.
• What are the tests for battery?
Conduct test – to check the capacity batteries
Impedance test – to check the utilization of active materials.
• What are the functions of charger?
1. For initial charging.
2. For float charging.
3. For battery equalizing charging.
4. For battery boost charging.
5. To supply normal DC loads.
• What is the rating of switchyard battery charger and batteries?
Switchyard is having Float cum boost charger of 282 V DC maximum and 100
Amps rated charger of six-pulse full wave thyristerised controlled rectifier.
Batteries are tubular 220 V DC. +ve plate is made up of low antimory lead selenium
(Pb) and –ve plate is made up of paste plate type (O2). Container or tube is made up
of polyester and glass fibre.
1. Momentary load 160 A / minute.
2. Continuous load 40 A / hour.
3. Cell voltage 1.8 V DC and total number of cells are 106 in battery bank.
4. Float voltage 2.16 V per cell to 2.18 V per cell.
5. Maximum system voltage is 106 * 2.18 = 242 V DC
Battery rated for 224 A for one minute or 80 A for 60 minutes.
Specific gravity 1110 ± 5 and specific gravity after 10 hrs discharge is 1150 ± 5.
• What are the protections provided in charger?
1. Over load (49).
2. Over voltage (59).
3. Short-circuit (3250 Amps).
4. Phase sequence and phase fail.
5. di/dt and dv/dt protection.
https://www.youtube.com/channel/UC4_D50vMu1wbQrPaLFYo6Eg https://www.youtube.com/channel/UC4_D50vMu1wbQrPaLFYo6Eg RRB JE, SSC AE/JE UPSSSC JE, SSC JE, CIVIL ENGINEERING MCQs, ELECTICAL ENGINEERING MCQs, preavious year quesion papers, dmrc, lmrc, drdo,rrb ntpc, ntpc, pgcil, dsssb, states board, GATE IES EE, ESE, ECE, ME, CE, IT & CS EXAM MATERIALS & OLD PAPERS Electrical Engineering https://t.me/pravendrarajpoot Daily news & current affairs in hindi & english fully updated Daily current affairs https://t.me/newsdailypkr Engineering Discussion group for your upcoming exams, you can ask your any query regarding your problem,👇👇👇 https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA PKR ELECTRICAL ENGINEERING I am sure this is the best place for you guys subscribe and get success IF YOU WANT TO JOIN ME ON TELEGRAM FOR PDF @newsdailypkr AE/JE EE, ESE, ECE, ME, CE, IT & CS EXAM MATERIALS & OLD PAPERS Electrical Engineering https://t.me/pravendrarajpoot facebook page:- Pravendra Kumar Rajpoot https://t.me/newsdailypkr https://chat.whatsapp.com/5AS7dNFTP4H4vVsiWsqHrT https://t.me/srk50 https://t.me/pravendrarajpoot https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA https://t.me/pravendrarajpoot Daily news & current affairs in hindi & english fully updated Daily current affairs https://t.me/newsdailypkr Engineering Discussion group for your upcoming exams, you can ask your any query regarding your problem,👇👇👇 https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA PKR ELECTRICAL ENGINEERING I am sure this is the best place for you guys subscribe and get success IF YOU WANT TO JOIN ME ON TELEGRAM FOR PDF @newsdailypkr AE/JE EE, ESE, ECE, ME, CE, IT & CS EXAM MATERIALS & OLD PAPERS Electrical Engineering https://t.me/pravendrarajpoot facebook page:- Pravendra Kumar Rajpoot https://t.me/newsdailypkr https://chat.whatsapp.com/5AS7dNFTP4H4vVsiWsqHrT https://t.me/srk50 https://t.me/pravendrarajpoot https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA
• What are the disadvantages of the maintenance free battery?
The life of battery is only five years.
The state of charge of a battery not knowing by the specific gravity of a battery. We
can know by voltage only.
• What are the problems of hydrogen concentration?
If the concentration of hydrogen more than 4% and less than 74% explosion
problems will be there. Therefore the concentration of hydrogen is restricted to less
than 1% by air changer ventilation system.
• Why lead acid battery requires so much large initial charging?
Initially for a new battery, negative plate will be PbO instead of Pb. To convert all of
them back to Pb, we need so much prolonged initial charging.
• What are the protections adopted in UPS or PMCC supply?
LV (incomer) or UPS input
CTZM, Over current, Short circuit protections
PMCC S or T input or UPS output
Under voltage (27), 51RYB, 51N protections.
• Write chemical equation for lead acid cell.
PbO2 + H2 SO4 PbSO4 +2 H2 (during discharge)
Pb + SO4 PbSO4 (during charge)
• Is the chemical reaction of plante cells same as tubular lead acid cells?
No. Plante cells having both electrodes are lead (Pb) only.
During charging, H2O H2 + O2
O2 react with Pb to form PbO2 + (+ve plate)
During discharge, Pb + c PbSO4 (on -ve plate)
While PbO2 Pb + O2 (on +ve plate).
That is converted back to lead.
Therefore PbSO4 formed only on -ve plate. That is sulphation problem are reduced
by 50%
• What are the advantages of plante type batteries?
Plante plate type batteries have longer life and can with stand rapid discharge.
• Why battery room should be located separately in a power station?
Possibility of battery explosion
Corrosive atmosphere by acid spray.
Fire hazard.
• What are the disadvantages of nickel cadmium battery?
Status of charge not known
Number of cells are more
Cost very high
Environmental protection agency considers cadmium as a hazardous material,
difficult to discard at the end of life.
• What are the effects of temperature in lead acid battery?
Higher electrolyte temp - ah capacity increases but life reduces.
Lower electrolytic temp - ah capacity reduces since chemical reaction rate reduces.
• Why ventilation is essential for Ni-Cad also?
Gases evolved H2 O2 can form explosive mixture.
• How H2 O2 generated in lead acid battery?
At end of charge, when most of the Pb is converted. H2 O2 generated from H2O. O2
appears as gas at positive plate. H2 at negative plate, i.e. gassing starts.
• Why current reduced after gassing?
Excessive gassing shortens the life of battery by scouring the active materials at the
surface of the plates.
• Why aged battery consumes more water?
As aging increases, antimony migrates to negative plate secondary cell reaction.
Therefore more charging current require more water consumption.
• What happens after aging?
Shedding of active material during charging.
Shedding increases with overcharging, heavy discharge, batteries short ckt.
• What is the other effect of low temperature?
When specific gravity decreases, acid freezing point increases, soon reached at low
temperature, volume increases container cracks.
• Why temperature correction required?
As temperature increases, specific gravity decreases. The hydrometer immersion is
more, showing lower readings. Therefore 10ºC raises, 7 points to be added,
corrected to get 27 ºC reading.
• What is meant by sulphation of the cell?
During the discharge lead sulphate is produced and during the charging the same is
converted back into lead and lead peroxide. If the cell is left under charged, lead
sulphate would form which will not reverse back into lead and lead peroxide during
charging. Due to this the cell will loose its original capacity.
• What you meant by shedding?
During the charging and discharging the active materials will undergo volumetric
changes. Due to this some of the material may not be retained with the parent
material and will shed and collected at the bottom of the container. This loss of
active material is called shedding. Due to this the cell will loose its capacity.
• Acid should be poured to water. Why is it so?
When acid and water is mixed lot of heat is generated. Hence there is chances of
splashing of the liquid. If water is poured to acid will splash causing injuries. In the
other case splashing will be of water with concentration of acid, which will not
hazardous as the other one.
• What types of lighting fittings are used in the battery room?
Flame proof acid resistant
• Why ungrounded 250V DC system adopted in our system?
The 250V DC system is feeding to some of the vital loads such as breaker control
etc. Even if one ground has occurred then also these controls should be available.
Continuous monitoring of ground current is employed to eliminate the by passing of
logic due to double ground.
• Why battery capacity limits to 20 minute?
Battery cost is more.
It is better to restore class 3 faster by DG set then putting large battery.
20 min, is enough to shutdown the unit safely.
• What are the main parts of lead acid battery?
a. Container
b. Lead dioxide positive plates
c. Lead negative plates
d. Post strap and seal assemble
e. Separators and retainers
f. Sulphuric acid electrolyte
g. Inter cell connector (lead plated copper)
• What are the different types of charging?
(Normally always) Float charging – 2.15V per cell
It maintains the battery fully charged condition during standby operation by
delivering a small amount of current to cancel the effect of battery natural selfdischarge.
Equalizing charging (2.7V/cell) once in 3 months
Recharge a battery capacity through recovering all useable active materials in the
cell plates.
Boost charging
Boost charging is a quick charging process, which is generally required, if the battery
is drained to a large extent.
• What is the double sulphate reaction?
Pb O2 + Pb + 2H2 SO4 ↔ 2PbSO4 +2H2O
During charging oxygen at positive plate and hydrogen at negative plate are
releasing.
• What are the effects of over charging?
Gassing
Heating
Loosening of plate active material
• What you mean by Drooping characteristics of charger?
When the charger is connected to excess load of charger rating the charger should
able to supply the load with out over loaded by maintaining the terminal voltage
within limit without over load trip. This called a drooping output voltage
characteristics.
• What are the effects of under charging?
Sulphation
Buckling of plates
• What are the effects of high temperature?
Gassing of electrolyte and evaporation
Service life is halved for every 8 deg increase above 25 deg.
• What are the effects of low temperature?
Increased electrolyte viscosity.
• What type of thermometer is used for acid batteries?
Alcohol type thermometer.
• What are the tests for battery?
Conduct test – to check the capacity batteries
Impedance test – to check the utilization of active materials.
• What are the functions of charger?
1. For initial charging.
2. For float charging.
3. For battery equalizing charging.
4. For battery boost charging.
5. To supply normal DC loads.
• What is the rating of switchyard battery charger and batteries?
Switchyard is having Float cum boost charger of 282 V DC maximum and 100
Amps rated charger of six-pulse full wave thyristerised controlled rectifier.
Batteries are tubular 220 V DC. +ve plate is made up of low antimory lead selenium
(Pb) and –ve plate is made up of paste plate type (O2). Container or tube is made up
of polyester and glass fibre.
1. Momentary load 160 A / minute.
2. Continuous load 40 A / hour.
3. Cell voltage 1.8 V DC and total number of cells are 106 in battery bank.
4. Float voltage 2.16 V per cell to 2.18 V per cell.
5. Maximum system voltage is 106 * 2.18 = 242 V DC
Battery rated for 224 A for one minute or 80 A for 60 minutes.
Specific gravity 1110 ± 5 and specific gravity after 10 hrs discharge is 1150 ± 5.
• What are the protections provided in charger?
1. Over load (49).
2. Over voltage (59).
3. Short-circuit (3250 Amps).
4. Phase sequence and phase fail.
5. di/dt and dv/dt protection.
https://www.youtube.com/channel/UC4_D50vMu1wbQrPaLFYo6Eg https://www.youtube.com/channel/UC4_D50vMu1wbQrPaLFYo6Eg RRB JE, SSC AE/JE UPSSSC JE, SSC JE, CIVIL ENGINEERING MCQs, ELECTICAL ENGINEERING MCQs, preavious year quesion papers, dmrc, lmrc, drdo,rrb ntpc, ntpc, pgcil, dsssb, states board, GATE IES EE, ESE, ECE, ME, CE, IT & CS EXAM MATERIALS & OLD PAPERS Electrical Engineering https://t.me/pravendrarajpoot Daily news & current affairs in hindi & english fully updated Daily current affairs https://t.me/newsdailypkr Engineering Discussion group for your upcoming exams, you can ask your any query regarding your problem,👇👇👇 https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA PKR ELECTRICAL ENGINEERING I am sure this is the best place for you guys subscribe and get success IF YOU WANT TO JOIN ME ON TELEGRAM FOR PDF @newsdailypkr AE/JE EE, ESE, ECE, ME, CE, IT & CS EXAM MATERIALS & OLD PAPERS Electrical Engineering https://t.me/pravendrarajpoot facebook page:- Pravendra Kumar Rajpoot https://t.me/newsdailypkr https://chat.whatsapp.com/5AS7dNFTP4H4vVsiWsqHrT https://t.me/srk50 https://t.me/pravendrarajpoot https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA https://t.me/pravendrarajpoot Daily news & current affairs in hindi & english fully updated Daily current affairs https://t.me/newsdailypkr Engineering Discussion group for your upcoming exams, you can ask your any query regarding your problem,👇👇👇 https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA PKR ELECTRICAL ENGINEERING I am sure this is the best place for you guys subscribe and get success IF YOU WANT TO JOIN ME ON TELEGRAM FOR PDF @newsdailypkr AE/JE EE, ESE, ECE, ME, CE, IT & CS EXAM MATERIALS & OLD PAPERS Electrical Engineering https://t.me/pravendrarajpoot facebook page:- Pravendra Kumar Rajpoot https://t.me/newsdailypkr https://chat.whatsapp.com/5AS7dNFTP4H4vVsiWsqHrT https://t.me/srk50 https://t.me/pravendrarajpoot https://t.me/joinchat/JObxeA7n6S4qvnegrGhTgA
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