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Vectoring Basics
Start With a Zero Reference Voltage.
Wye – ENA
Delta – EBA
Vectoring Basics
Potential – Open Arrow.
Current – Closed Arrow.
Arrowhead Denotes Polarity.
Current Enters the Polarity side of a Current Coil.
Cannot have a C-Phase without first having A-Phase and B-Phase.
The ONLY Current Coil that is ever reversed is B-Phase.
B-Phase Current Coil Reverses when you Alter it.
Half Coils and ‘Z’ Coils are considered Altered.
All Meter Elements Have Forward Torque at Unity Power Factor.
Forward torque means less than 90 degrees between
the Potential coil and the current coil vectors.
Sequence for Vectoring
Learn and Memorize the Three Basic System Vector Diagrams.
Learn and Memorize Meter Footprints.
The Meter Footprints show the Potential Connections and Currents being measured. Labeling the connections is helpful.
Apply the Rules Regarding Forward Torque and Which Current Coils may be Reversed.
Draw the Meter Vectors.
Create a hypothetical load.
Do the Math.
Two Element Meters
Forms 12 & 5 (Conforming)
Form 12 as a Network Meter
System Vectors.Blondel Conforming Meter
Meter Vectors.
Ina Inb Ena
Enb
Network Service Vectors
Ina Inb Ena
Enb
Network Meter Vectors
Form 12 as a 3Ø 3-Wire Meter
Form 12 as a 3Ø 3-Wire Meter
Drawing the Meter Vectors
Apply the Rules Regarding Forward Torque and Which Current Coils may be Reversed.
Draw the Meter Vectors.
Current Coils are unaltered. No current vector changes.
Potential coils are between A & B Phase and B & C Phase.
Polarity is not at B-phase either time.
Drawing the Meter Vectors
Create a Load
40 HP 3-phase 240 Volt well pump (For simplicity 750w per HP & 1.0 pf)
30000 watts of 3-phase
30000 / (240 x 1.73) = 72.17 amps
Form 12 Vectors
Total watts = 30000
‘A’ Element watts =
240 x 72.17 x cos 30º
= 15000 watts
‘C’ Element watts = 240 x 72.17 x cos 30º
= 15000 watts
Total: = 30000
Form 15
Two Meters in One.
Form 2 Plus Form 1.
BØ is Altered/Reversed.
4-Wire Delta Service Vectors
Unlike the 3-Wire Delta, the
4-Wire Delta has reference to
ground for all three phase
Voltages.
Also, each current coil has the
ability to measure single-phase
Current.
Form 2
Eba Ia Ib
3-Wire 120/240
System Vectors
System Vectors.
Current coils are ½ toCompensate for Potential Coil being across 240 Volts
Meter Vectors.B-Phase Current is Reversed.This Creates Forward Torque forBoth Current Coils Interactingwith the Potential Coil.
Form 1
2-Wire
System Vectors
Ea Ia
2-Wire
Meter Vectors
Ea Ia
System Vectors.
Meter Vectors.
Drawing the Meter Vectors
Apply the Rules Regarding Forward Torque and Which Current Coils may be Reversed.
Draw the Meter Vectors.
Current Coils are ½. This means
B-Phase is reversed.
Voltage is Between A and B-
Phase with Polarity at A.
Voltage and current are between
neutral & C-Phase with polarity at C.
Select the Vectors
Form 2
Eba Ia Ib
3-Wire 120/240
System Vectors
Invent a load:
A-phase has 1200 watts.
B-phase has 1800 watts.
A-B phase has 3600 watts.
1200/120=10 amps
1800/120=15 amps
3600/240=15 amps
6600 watts total
Ia = 10+15 = 25 amps
Ib = 15+15 = 30 amps
Form 2
Remember current coils are
½ and Potential is Eba.
25amps/2 x 240 x cos 0º
+ 30amps/2 x 240 x cos 0º
= 6600 watts
Form 1
Form 15s Vectors
Create a Load
4 HP 3-phase 240 well pump (For simplicity 750w per HP & 1.0 pf)
1200 watt 120 volt heater (A-phase)720 watts of lighting (B-phase)
3000 watts of 3-phase3000 / (240 x 1.73) = 7.17 amps
1200 watts single-phase (A)1200 / 120 = 10 amps
720 watts single-phase (B)720 / 120 = 6 amps
Total = 4920 Watts
How the meter sees the load
Make them match
Total watts = 3000 + 1200 + 720 = 4920
2s section watts = (A) 240 x 7.17/2 x cos 30º
+ 240 x 10/2 x cos 0º
= 745 + 1200 = 1945
(B) 240 x 7.17/2 x cos -30º
+ 240 x 6/2 x cos 0º
= 745 + 720 = 1465
1s section watts = (C) 208 x 7.17 x cos 0º = 1502
Total: 1945 + 1465 + 1502 = 4912
Exercise
Exercise
Exercise
The End
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