Energy Measurements

Question 1

Self contained meter socket connections

Answer 1

•Don’t require instrument txs
• 200A and 600V
• single phase and three phase

Question 2

Single phase meter sockets r designed for?

Answer 2

120/240V
120V single phase service
120V/208V three wire network service
These r universal

Question 3

120V/240v three wire service
Need to know

Answer 3

Common house service
4 jar meter base
No connection to neutral
No tickler

Question 4

120 V single phase service is used for?max ampacity?

Answer 4

Billboards
30 A limit
4 Jaw meter base
Only 120V

Question 5

Instrument transformers are required when ? Primary or secondary?

Answer 5

Large services over 200A or 600V
•secondary side

Question 6

CT-Current transformer need to know

Answer 6

CT connected in series with load
•low impedance on primary, produces a secondary voltage
•revenue metering over 200A
And want it reduced to 5A on secondary

Question 7

Which meter bases have a ‘tickler’

Answer 7

4wire delta
4 wire wye
3 wire network

Question 8

CT’s and PT’s used for metering have a additive or subtractive polarity?

Answer 8

Subtractive

Question 9

PTs standard rated revenue voltage?

Answer 9

120V

Question 10

Network service 120/208V where is commonly used?

Answer 10

City center and residential if 120V
5 jaw meter
2 phase three wire
Common conductor doesn’t carry unbalanced

Question 11

Pts or CT’s need their primaries fused ?

Answer 11

Pts cuz they r used to step down the voltage

Question 12

What must happen to a meter of an energized CT before removing ?

Answer 12

CT’s secondary must be short circuited BEFORE the meter is disconnected

Question 13

Ammeter transfer switches uses which action ?

Answer 13

Make before break
Or overlapping

Question 14

The secondary of an energized _ should never have an open circuit

Answer 14

A CT will never have a fuse or cb on secondary side
•secondary of CT must always be connected

Question 15

Three types of CTS?

Answer 15

Wound primary
Bar type
Toroidal

Question 16

Two major functions for CTs

Answer 16

Reduce current and isolate high voltage on primary

Question 17

Which instrument transformer needs their secondary grounded?

Answer 17

Both

Question 18

When is the tickler required?

Answer 18

3 phase systems and 3 wire network

Question 19

What do electricians connect for supply authority?

Answer 19

Primary of CTs
Mount cabinets
Conduit

Question 20

Pts two major functions?

Answer 20

Step down voltage and isolate high voltage from meter