Battery

Question 1

Batteries connected in series increase what?

Answer 1

Voltage

Question 2

Batteries connected in parallel increase what?

Answer 2

Current

Question 3

Batteries store and supply DC for use in what substation applications.

Answer 3

Relaying, S/C, breaker trip and close coils

Question 4

In APS medium and large substations, the typical DC tripping voltage is based on……

Answer 4

125 VDC system

Question 5

In APS medium and large substations, the typical DC S/C voltage is based on…..

Answer 5

24 VDC system

Question 6

Battery voltage monitors and alarm for what conditions?

Answer 6

low tripping battery voltage, positive/negative grounds, high tripping battery voltage

Question 7

Where would you expect to find the battery voltage monitor in the substation?

Answer 7

on a panel near the station annunciator

Question 8

Where would you expect to find the battery charger and DC control panel in a substation?

Answer 8

In a separate room referred to as the battery room

Question 9

Explain how a battery charger works?

Answer 9

It takes the incoming AC source and converts it to DC to charge the batteries. The charge rate can set to slow trickle (normal charge) or quick charge.

Question 10

Explain the term “float”?

Answer 10

slow trickle charge rate used to maintain battery voltage level

Question 11

Explain the term “equalize”?

Answer 11

Fast or quick charge rate to increase or boost voltage level.

Question 12

Explain the term “charging amps”?

Answer 12

the electrical DC current supplied by the charger to charge the battery

Question 13

Smaller substations on the APS system use a tripping battery voltage of….

Answer 13

125 VDC or 48 VDC

Question 14

Why is it important to keep substation batteries well maintained?

Answer 14

Batteries provide DC stored energy critical to substation relaying and control. DC power is used to maintain substation reliability by supplying uninterrupted power to relays for clearing faults and to breaker trip/close coils for breaker open/close operations

Question 15

Who would you notify for battery problems/maintenance?

Answer 15

Substation maintenance Dept battery crew

Question 16

Who would you notify for other substation DC problems not directly related to batteries?

Answer 16

Substation maintenance Dept P&C group

Question 17

Batteries require a controlled environment to operate efficiently and safely. What are some environmental considerations?

Answer 17

too cold, too hot, too little ventilation, too dirty, too close to sparks or fire, indirect sunlight and flammable storage

Question 18

Where do battery chargers get their AC supply voltage?

Answer 18

from the substation station power transformer

Question 19

What would happen if the AC supply to substation batteries was lost for an extended period of time

Answer 19

There would be no AC supply to the battery charge so the batteries could not re-charge. the batteries voltage would decay over time under DC load until the DC voltage would be too low to reliably operate the equipment.

Question 20

What is the EMS display called that monitors battery voltage and from what directory can it be found?

Answer 20

Station battery voltage display, found from the Transmission Directory

Question 21

How might a “control cubicle high temp” alarm affect station batteries?

Answer 21

Batteries are rated at 77 F. Higher temps can cause loss of some battery capacity and battery life.

Question 22

Explain what a DS6Z1 125V DC alarm is?

Answer 22

DS=Desert Springs… 6Z1 = the alarm window ID at the substation annunciator. 125V DC = the battery monitor is in alarm

Question 23

Substations are equip. with positive and negative ground lights. at what brilliancy, compared to each other, are they normally lit?

Answer 23

compared to each other that would normally be at equal intensity and dimly lit

Question 24

How would you interpret a dim positive ground light with a brilliant negative ground light?

Answer 24

the substation has a strong ground on the negative leg

Question 25

How would a strong ground impact tripping batteries.

Answer 25

the batteries would deplete more rapidly due to the increase constant load on the ground.

Question 26

A Rose Garden station battery ground alarms comes in along with a low operating limit alarm at 118 V DC and a RSG442 SEL 351 relay trouble alarm. What do you think night have happened?

Answer 26

most likely would be RSG442 trip/close coil is burning, creating a strong DC ground, pulling the battery voltage down due to the ground current and putting the SEL 351 relay in alarm, since the SEL 351 monitors the trip coil voltage. DOC would need to be advised and prepared to unload the feeder

Question 27

What would you expect if a battery voltage came in at 147V DC?

Answer 27

Have Sub Tech check battery voltage at the battery charger to insure EMS alarm is correct. Charger could have possibly be left on equalize (quick charge) return to “float”

Question 28

A storm has swept through AZ and you receive a battery voltage at 122V DC with a station battery alarm, what would you expect to find?

Answer 28

Possibly door was opened by storm and the battery charger got wet and tripped off line or it internally grounded

Question 29

A heavy storm swept through the Phoenix area and EMS is reporting rapidly decaying battery voltage at several unrelated substations, yet no battery monitoring alarms or GSA have came in. What might be the problem?

Answer 29

Wet transducers reporting incorrect EMS values

Question 30

Who would you notify if you suspect wet transducers

Answer 30

EOS, the next working day