The value of 1 revolution of the meter disk, Expressed in watt hours.
Register RatioThe number of turns of the 1st gear of the register to cause the 1st (or right hand) dial pointer to complete 1 full revolution which = 10,000 watt hours or 10kwhrs.
Gear RatioThe number of turns of the meter disk to cause the 1st (or right hand) dial pointer to complete 1 full revolution = 10,000 watt hrs or 10kwhrs.
Reduction at ShaftThe ratio between the number of teeth on the 1st gear of the register to the number of entries on the disk shaft.
Register Constant or Multiplier
Multiplier of the register, due to gearing.
Transformer FactorMultiplier of the register, due to CT’s and/or CT X PT ratios.
Amperage used with line voltage to set the speed of the disk in 1 hour’s time. (1000Rph 1phase)(500Rph Poly phase)
Watt-hour Constantx Transformer Factor
The average rate of consumption over a specific period of time
The inverse of the number of current circuits in series under test.
(Establishes the Kh of individual elements)
An electrical load expressed in watts or kilowatts without a relationship to time. E x I=Watts
An electrical load expressed in watts or kilowatts times the number of hours it’s used.
E x I x time factor = Kwhr
Stator (Meter Element)
The unit that provides the driving torque in a watt-hour meter.It includes the Potential-Coil, the Current-Coil and the related framework to provide a magnetic flux or path
In a system of N-conductors, N-1 metering elements properly connected, will measure power and/or energy consumed, provided that all potential coil(s) have a common connection in which no current circuit(s) are connected.
Test Amps Formula
E x I x CC x TF1,000 Rph for single phase500 Rph for Polyphase
Register Ratio Formula
10,000 x Kr TFxKhxRs
Kh x 3600 x revsTime in seconds
10,000 x Kr
TF X Rr x Rs
10,000 x KrTF x Kh x Rr
Rr x Rs
Kh x Rr x Rs x TF
Volts x Amperes (or) E x I
Volts x Amperes x Time (or) E x I x Time
E x I x CCx TF 1000
where “I” is equal to the amperage
on the meter under test
Draw and label a FM5, FM6, FM8 and FM9 socket and a-base meter
Draw the following meter banks and the corresponding meters (a-base and socket) for each bank:
3W3phase open delta
4W3phase closed delta
Draw and connect a FM1 socket Preferred, Non-preferred, and set on neutral
What is an Ohm?
The practical unit of electric resistance.
Define Percent Registration
The ratio of the actual registration of the meter to the value of the quantity measured in a given time, expressed as a percentage
What is capacitance?
The property of an electric circuit which allows storage of energy and exists whenever two conductors are in the close proximity but separated by an insulator or dielectric material
What is conductance?
The ability of a substance or body to pass an electric current
A device installed in a meter to prevent reverse rotation of the meter disk
What is a demand register?
A mechanism that indicates maximum demand and also registers energy used
What is a cycle?
One complete set of positive and negative values of an alternating current or voltage
The practical unit of electromotive force, or potential difference
The industry wide standard to describe the meter construction and wiring.
Transformer Factor Formula
TF = 10,000 x Kr
Kh x Rr x Rs
What is the KW demand on an Itron Sentinal FM9 with 6000 internal pulses? Show work
How many internal pulses are on an Itron FM16 with a demand of 36KW? Show work
Be able to calculate watts, TF and PKh with values provided.
Prove Voltages on both Delta and Wye services using Trigonometry
Misapplication of a FM2 on a Wye bank. Draw and explain. Also what % the meter registers vs customer uses on phase to phase loads and phase to neutral loads.
Refer to Vector Class Powerpoint pg 8-9
Draw and explain a FM12 where the 5th terminal is not connected to ground.
Also what % the meter registers vs customer uses on phase to phase loads and phase to neutral loads.