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DC System Flashcards

1
Q

station battery charger failure light

A

if output current falls to below 2% of rated output current for more than 30 seconds

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2
Q

fully discharge battery formula

A

PbSO4 + PbSO4 + 2H2O
(-) (+) (water)

PbSO4 = Lead sulfate

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3
Q

fully charged battery formula

A

Pb + PbO2 + 2H2SO4

-) (+) (liquid

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4
Q

control room battery charger ammeter

A

0 - 100 A

Normally 30A

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5
Q

VM and AM on station battery charger

A

VM - 0-200V 135V floating

AM - 0-75A 20-25A

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6
Q

station battery charger
High AC Volt High DC Volt
Low AC Volt Low DC Volt

A

High AC - 115% High DC - 144V

Low AC - 85% Low DC - 120V

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7
Q

control room 125V battery bus voltmeter

A

digital 135V +/- 1V

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8
Q

control room 125V battery voltmeter

A

0 - 150 V

Normal 135V

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9
Q

control room station battery ammeter

A

-100 - 300
normal just to - side of 0 (trickle charge)
- charging
+ carrying load

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10
Q

control room ac distribution main bus voltmeter

A

0 - 150V

normally 116V

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11
Q

control room ground detecting voltmeter

A

-150 - 150V
Should be 0
tells how hard the ground is

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12
Q

ground detector 125V bus annunciator

A

D-3 relay +- 50mA

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13
Q

control room 48V DC system voltmeter

A

0-60V

normally 54V

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14
Q

control room ground detector test switch

A

+ and - test switch

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15
Q

resistors are set so ground detector VM and D3 indicate same thing

A

.

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16
Q

VM and AM on supervisory battery charger

A

VM 0-80 54V normal

AM 0-50 20A normal

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17
Q

AC relays pickup value

A

85% rated V

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18
Q

DC 125V relay pickup and drop out

A

pickup is 80% ~100V - at 100V relays may not pick up

dropout is 70% ~85V - at 85V normally picked up relays will start to drop out

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19
Q

control room ac distribution main bus ammeter

A

0-50A 25A

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20
Q

battery room low ventilation

A

air flow switch

63BRA @ no air flow

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21
Q

do we use the battery chargers ground detection

A

no, we use our own D3

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22
Q

specific gravity

A

strength of concentration of electrolyte
weight of a volume of a substance
————————————————–
weight of an equal volume of fresh water

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23
Q

what is a pilot cell

A

weakest cell in the bank

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24
Q

why do you select a pilot cell

A

to indicate the general condition of the entire batter bank in regard to voltage, specific gravity, and temperature

25
how is the pilot cell determined
by specific gravity, voltage, and temperature determined initially and confirmed or changed quarterly
26
what measurements does a digital hydrometer give you
specific gravity & temperature
27
if you have to add distilled water to a cell, how long does it take to mix so you get an accurate specific gravity reading?
6 weeks or more unless you perform an equalizing charge
28
when can you add electrolyte
when it is known that the electrolyte was spilled from a cell
29
what is the electrolyte we use
diluted sulfuric acid
30
what charge does the trickle charge (float) keep our batteries at?
2. 23V/Cell | 134. 7 V DC (135V)
31
how fast to recharge?
not any faster than it was discharged
32
equalizing charge
2.33V/cell until charging current stabilized of 4 consecutive hours for a minimum of 35 hours for lead antimony max of 72 hours done when specific gravity and voltage hasn't changed for 2 hours
33
while recharging, current will break down water in electrolyte to H and O which are given of in the form of gas
.
34
when should equalizing charge be given
if any cell falls below 2.13V, or rises above 2.38V corrected for temp when corrected specific gravity has fallen more than 10 points at least once every 24 months
35
correcting voltage for temp
voltage of a warm cell is lower add .003V for each degree F that the cell is above average temp of other cells, subtract if cooler
36
what type of cells do we have
single vented tubular cells
37
what are the 2 groups of coated lead plates in a battery
positive and negative electrodes
38
do batteries have an even number of plates
no, always have 1 extra negative plate
39
what determines the number of cells used
total voltage required
40
what does the current supplied by a storage battery depend on
it's voltage, physical condition, & resistance of the load circuit
41
what determines the resistance of a battery
the condition of the electrolyte, the size of the plates, and the # of plates
42
what limits the max current of a battery will supply
the internal resistance of the cell
43
a storage cell consists of
a group o positive plates connected, a group of negative plates connected, separators, electrolyte, suitable container
44
what does voltage of a cell depend on
the material of he electrodes and electrolyte
45
+ plate | - plate
lead dioxide | sponge lead
46
what is generated at + and - plate
+ oxygen gas | - hydrogen gas
47
types of storage battery
stationary or portable | lead acid/nickel-iron-alkaline/nickel-cadmium
48
battery PPE
goggles and face shield appropriate to the chemical and electrical hazard acid resistant rubber gloves protective rubber apron and safety shoes lifting devices of adequate capacity when required
49
what periodic inspection do we have
daily - visual weekly quarterly 5 year load test - load batteries for 8 hrs @ AH rating, 1st hour take readings (SG, V, Temp) every 15 mins, next 6 hours take readings ever hour, last hour take readings every 15 mins
50
initial records
battery terminal float voltage SG of each cell corrected to 25* C individual cell voltages electrolyte level temp of one cell on each row of each rack cell to cell and terminal connections, resistance readings
51
weekly maintenance
observe appearance and cleanliness read and record charger output A and V observe electrolyte levels check for cracks in cells or leakage of electrolyte check for evidence of corrosion at terminals or connections check ambient temp and condition of ventilating equipment read and record pilot cell V, Temp, and SG read and record battery terminal voltage
52
quarterly maintenance
SG of each cell V of each cell battery terminal voltage (compare control room to battery charger VM) temp of one cell on each row or rack detailed visual inspection of each cell and integrity of rack
53
Station battery nameplate
``` Powersafe 6 opzs600 60 cells - 13 plates per cell (7-,6+) 2.23V per cell 1.24 kg/L specific gravity at 20*C 648 amp hour at 8 hour rate Diluted sulphuric acid ```
54
Station battery charger nameplate
``` GNB Type SCR AC Input 3 phase 60 cycle 480V 16A DC Input 130V 50A 85mV ripple ```
55
Items on station battery charger
``` DC VM 0-200V @135V Floating DC AM 0-75A @20-25A Red Lights High AC V High DC V 2.4V/cell Low AC V Low DC V 2.0V/cell Charger failure light Positive ground detector Negative ground detector Toggle switch for load sharing connection to split the load Toggle switch to switch between floating and equalizing charges Floating charges set screws Equalizing charge set screws Lamp test push button Relay reset push button ```
56
Supervisory battery nameplate
``` Varta VB4118 24 cells - 17 plates/cell (9-,8+) 2.23V per cell 268 amp hour 1.24 kg/l specific gravity at 20*C Diluted sulphuric acid ```
57
Supervisory battery charger nameplate
``` GNB AC Input 3 phase 60 cycle 480V 8A DC output 48V 50A 30mV ripple charge ```
58
Items on supervisory battery charger
DC VM 0-80V @54V | DC AM 0-50A @26A
59
Inverter set nameplate
``` LaMarche Type A31 DC Input 120V 12A No Load 105A Full Load AC Output 120V 83.33A 10KVA ```

2B (3 decks)

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