# Meter Theory (1st 2weeks) (2016)

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1. Name the 3 major types of meters.
• Electro-mechanical A-base
• Electro-mechanical Socket
• Solid State Socket
2. Name the major parts of an electromechanical meter.
Cover, Base, Stator, Disk, Register, Permanent magnet
3. Name the major parts of a Solid State meter
Cover, base, current coils, circuit board, digital display, CT's or Hall effect pickup
4. Define Drive
A voltage flux and a current flux acting on the meter disk in a time and space displacement.
5. Define Drag
A permanent magnet calibrated at the factory with a known amperage and voltage to set the speed of the meter disk
6. Define Lag
Potential flux must lag current flux by exactly 90 electrical degrees at unity power factor to establish maximum torque of the meter disk at any given load power factor
7. Define record
A kilowatt hour register counting meter disk revolutions and displaying them in kilowatt hours. This is accomplished at the reduction at shaft.
8. What are the 4 basic functions of an electromechanical meter?
Drive, Drag, Lag & Record
9. Kh
Watt hour constant The value of 1 revolution of the meter disk, Expressed in watt hours.
10. What are the 4 basic meter functions of a solid state meter? Define each.
• -Sample: Samples current and voltage at the CT’s and meter stabs
• -Calculate: Multiplies current and voltage, in phase, to calculate watts being used
• -Convert: Converts data into a digital signal to be sent to, and displayed, by the digital display
• -Display: Displays load in Kwhrs or KW for billing purposes
11. Rr
• Register Ratio
• The 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.
12. Rg
• Gear Ratio
• The 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.
13. Rs
• Reduction at Shaft
• The ratio between the number of teeth on the 1st gear of the register to the number of entries on the disk shaft.
14. Kr
• Register Constant or Multiplier
• Multiplier of the register, due to gearing.
15. TF
• Transformer Factor
• Multiplier of the register, due to CT’s or CT X PT ratios.
16. When a meter is first energized, what first appears on the meter display?
Segment check
17. Kh Formula
• 10,000 x Kr
• TF X Rr x Rs
18. Rs Formula
• 10,000 x Kr
• TF x Kh x Rr
19. Rg Formula
Rr x Rs
20. Kr Formula
• Kh x Rr x Rs x TF
•        10,000
21. Draw a pictoral and schematic view of a single phase delta service and include:
-connections to secondary lines
-label voltages at the secondary lines
-draw and connect FM1/FM2/FM12 sockets
22. Using the TA formula determine Kh of meters show work
23. What is the test amps formula?
• E x I x CC x TF
• 1000rph (single phase)
• 500rph (poly phase)
24. What is the formula for Ohm's Law?
E=I x R
25. What is the formula for Pythagorean's Theorem?
a2 + b2 = c
26. Define ERT and what it does?