Emergency power

Question 1

how does voltage and current work depending on series parallel?

Answer 1

Series: voltage goes up,current stays same
Parallel: voltage stays same, current goes up
In parallel high current same voltage
In series high voltage same current

Question 2

12V batter has open cct of 13.2V when delivering 125A to a load the voltage across load is 10.8V what is terminal resistance?

Answer 2

13.2-10.8=2.4V
2.4V/125A=19.2mA

Question 3

When is it best to test battery?

Answer 3

No load test

Question 4

Amp hour capacity based on?

Answer 4

20hour

Question 5

Reserve capacity based on?

Answer 5

25 hour

Question 6

What are CCA and some characterisitics?

Answer 6

Cold cranking amps test at -18 inder load for 30seconds end voltage maintained at 1.8vpc which is 7.2V

Question 7

What are MCA and some characterisitics?

Answer 7

Marine cranking amps tested at 0 degrees and are usually 20% greater then CCA because of temp

Question 8

DoD

Answer 8

Depth of discharge-when use batter for a long time its the unusable part at the top of the battery

Question 9

Soc

Answer 9

State of charge- rest of the battery that is usable

Question 10

Hydrometer Floating, Sinking, RED, WHITE, GREEN

Answer 10

Floating= charged
Sinking= dishcarged
Red= discharged poor condition
White= charging
Green= charged, good condition

Question 11

Hydrometer reading?

Answer 11

taken at 25 degrees, 0.7 up/down for every degree away from 25
eg. SG reading of 1280 taken at 12 degrees so 1280-(13*0.7)= 1271

Question 12

Lead acid batter SG for fully charged and

Answer 12

Fully charged: 1280, 12.6 open cct voltage
Discharged is 11.9 open cct voltage

Question 13

Adding acid to batter what are the steps?

Answer 13

Always add acid to water not reverse

Question 14

Benefits of lithium ion battery?

Answer 14

-high energy density
-high efficiency compared to other batteries

Question 15

What is battery capacity?

Answer 15

amp hour

Question 16

What is battery energy?

Answer 16

KW/hr to calc this do volts x amp hour. question will be what has more energy do the calculation and then answer

Question 17

Meter reads 48V then all of a sudden goes to 0V , what is the possibility?

Answer 17

Possibility that the internal is open cct

Question 18

Lead acid battery Fully ccharged and discharged characteristics

Answer 18

FC: internal resistance is low/ decreased
FD: internal resistance is high/increaed, older it cand be high, sulfation

Question 19

Battery connecting and disconnecting procedure?

Answer 19

Disconnecting: remove negative first
Connecting: connect positive first

Question 20

if batter is barely used what state would it be charging at?

Answer 20

Float

Question 21

3 stage chargeer is modern charger with 3 stages what are they?

Answer 21

Phase 1: cosntant current
Phase 2: constant voltage
Phase 3: minimum current and voltage

Question 22

What voltage at each coil in wye connected generator if line voltage is 480?

Answer 22

Series Wye: 480/root 3= 277/2= 138.5 at each coil
Parallel: 480/root3= 277 at each coil
GOING TO BE GIVEN LINE VOLTAGE SO FIGURE OUT ACCORDINGLY

Question 23

To share reactive power what do we do?

Answer 23

Reactive power is KVARs we need to change variable resitance which is field excitation

Question 24

To share true power what do we do?

Answer 24

True power is KW we need to change govenor or prime mover

Question 25

How long do we have to exercise generator/ plant generator?

Answer 25

30 minutes @ full load every week

Question 26

What is major function of automatic transfer switch

Answer 26

ensures 2 sources are always isolated, never be able to connect them together

Question 27

Generally what type of switch is it for ATS?

Answer 27

3 phase double throw(basically if they connect to 2 supplies its double throw)

Question 28

What are the generator stages?

Answer 28

Test- simulates power outage, and has load Auto-normal position ATS does all the work Start- starts but does not carry any load and to turn off, turn switch to stop and whne completely off turn switch to auto Stop- used for servicing generator and ATS will not operate automatically

Question 29

What voltage being read in the secondary of a PT from 2-AC what will the voltmeter read?

Answer 29

12V

Question 30

Emergency/ Normal auxiallry contacts, what is the max rating for the contacts?

Answer 30

10A 400VAC cant be used for DC/battery

Question 31

Spare contacts max rating?

Answer 31

3A 28VDC can only be used for DC like a battery.

Question 32

What type of tiemrs are these?

Answer 32

On delay says in the drawing notes

Question 33

HOT

Answer 33

hold over timer

Question 34

TRT

Answer 34

retransfer relay

Question 35

CDT

Answer 35

cool down timer

Question 36

WUT

Answer 36

warm up timer

Question 37

TRX

Answer 37

transfer relay

Question 38

OCT

Answer 38

over cranking timer

Question 39

What is break before make?

Answer 39

open normal/main breaker first then close the emrgency power breaker

Question 40

What is MOV?

Answer 40

metal oxide varistor

Question 41

What is purpose of a bypass switch?

Answer 41

when inverter fails, by pass ensures we still get supply from power supply