Energy Measurements Flashcards
Self contained meter socket connections
•Don’t require instrument txs
• 200A and 600V
• single phase and three phase
Single phase meter sockets r designed for?
120/240V
120V single phase service
120V/208V three wire network service
These r universal
120V/240v three wire service
Need to know
Common house service
4 jar meter base
No connection to neutral
No tickler
120 V single phase service is used for?max ampacity?
Billboards
30 A limit
4 Jaw meter base
Only 120V
Instrument transformers are required when ? Primary or secondary?
Large services over 200A or 600V
•secondary side
CT-Current transformer need to know
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
Which meter bases have a ‘tickler’
4wire delta
4 wire wye
3 wire network
CT’s and PT’s used for metering have a additive or subtractive polarity?
Subtractive
PTs standard rated revenue voltage?
120V
Network service 120/208V where is commonly used?
City center and residential if 120V
5 jaw meter
2 phase three wire
Common conductor doesn’t carry unbalanced
Pts or CT’s need their primaries fused ?
Pts cuz they r used to step down the voltage
What must happen to a meter of an energized CT before removing ?
CT’s secondary must be short circuited BEFORE the meter is disconnected
Ammeter transfer switches uses which action ?
Make before break
Or overlapping
The secondary of an energized _ should never have an open circuit
A CT will never have a fuse or cb on secondary side
•secondary of CT must always be connected
Three types of CTS?
Wound primary
Bar type
Toroidal
