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Flashcards in Voltage/Protection & Control Deck (38):
1

What does active or real power do

performs the active work

2

What does reactive power do

builds the magnetic fields that enable power to do the work

3

Voltage control is the control of what

reactive power flow

4

Equation to determine shunt capacitor output

MVARactual = MVARrated x {Vactual / Vrated}2

5

Why are series capacitors used

used to reduce the inductive reactance on transmission line, thus increasing the line transfer power capability

6

Static VAR compensators can be used for what

control both capacitance and inductance var

7

can transmission lines be removed / added to service has a form of voltage control

yes, only after engineering has perform studies to determine there will not be a negative impact

8

what is surge impedence loading (SIL)

SIL is the point where the active power flowing on a power line reguires 0 MVAR from the rest of the system to

9

what is below SIL

When load is light, the line becomes more capacitive, producing MVAR

10

what is above SIL

when load is heavy, the line becomes more inductive, absorbing MVAR

11

under what conditions shall the TO have sufficient reactive resources

under normal and contingency conditions

12

What happens when a AVR is out of service

the TO will direct the GO to maintain or change either its voltage schedule or it reactive schedule

13

who notifies who when the status or capability changes of either a generator or AVR

GO notifies TO

14

Ferranti effect raises the voltage where

on the line and the bus at the closed end

15

how long does a GO have to notify a TO of generator changes like AVR status

30 mins

16

what effect is there when you adjust ULTC when there is not enough primary side voltage

Lowers ULTC primary voltage, there is little to no effect on secondary voltage and could lead to voltage collapse

17

How does reactive power flow

when volatge is on schedule (power angles low, below 10 degress) MVAR will flow from the high to low voltage. When power angles are high MVAR will flow from the low to high voltage

18

TO's and GO's coordinate their voltages schedules to...

ensure they do not burden neighboring TO's with excessive power flow across the tie lines

19

What are types of protective relays?

Overcurrent, ground, differential, distance and monitoring (temp alarms)

20

What are types of auxiliary relays?

tripping, lockout, timers, re-closing and regulating (like AVR)

21

distance relay

21

22

sync relay

25

23

Instantaneous overcurrent

50

24

timed overcurrent

51

25

directional overcurrent

67

26

lockout relay

86

27

differential relay

87

28

distance relays remove what kind of fault

phase to phase

29

what kind of zone is a differential relay

closed zone, power in must equal power out

30

what is the most frequently type used protection

ground

31

zones of protection, zone 1 covers how much of the transmission line

90% and trips instantaneously if detects fault within its zone

32

zones of protection, zone 2 covers how much of the transmission line

120-150%, it is on a time delay and considered a backup to zone 1

33

zones of protection, zone 3 covers how much of the transmission line

150-300% is on a time delay set longer then zone 2, also backup to zone 1&2

34

overcurrent relays are used as backup to what relays

distance and differential

35

what do synch check repays monitor

frequency, voltage and phase angle

36

who is notified if a protective relay or equipment failure reduces system reliability

the TO shall notify its RC and other affected TO's and BA's

37

transfer trip signals are a form of pilot relaying. what are some communication channels pilot relays use?

pilot wires, lowerline carrier, satellite, fiber optics, microwave and telephone lines

37

What type of Mvar is ultilized first

Shunt capacitors to increase generator dynamic reactive reserve