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