Vectoring BasicsStart With a Zero

Reference Voltage. Wye – ENA Delta – EBA

Vectoring Basics Potential – Open Arrow. Current – Closed Arrow. Arrowhead Denotes Polarity. A & C Currents Enter the Polarity side of a Current Coil. The ONLY Current Coil that is ever Reversed is B-Phase. B-Phase Current Coil Reverses Whenever you Alter it. Half Coils and ‘Z’ Coils are considered altered. All Meter Elements Have Forward Torque at Unity Power

Factor. You cannot have a C-Phase without first having A-Phase and B-Phase. Forward torque means less than 90 degrees between the Potential coil and the current coil.

Sequence for Vectoring Learn and Memorize the Three Basic Service 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.

One Element Meters

Forms 1 & 3 (Conforming) Forms 2 & 4 (Non-Conforming)

Form 1 and 3 System Vectors.

Meter Vectors.

Form 1 and 3 Simple 2-Wire Circuit. N=2 , N-1=1 Element. Conductor w/o Current Coil

is Common to the Potential Coil.

An Element is One Current Coil and One Potential Coil.

Form 2 and 4 Service / System Vectors.

Current coils are ½ to Compensate for Potential Coil being across 240 Volts

Meter Vectors. B-Phase Current is

reversed.

This Creates Forward Torque for Both Current Coils Interacting with the Potential Coil.

Form 2 and 4 3-Wire Circuits. N=3 , N-1=2. # of Coils = 1.

Note-Some may be Tempted toConsider this a 1 ½ Element Meter.Current Coils are Half. Two HalfCoils Makes One Full CurrentCoil.

Service Vectors and Footprint

Label the Meter Connections

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 meansB-Phase is reversed. Voltage isBetween A-Phase and B-Phasewith Polarity at A-Phase.

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 meansB-Phase is reversed. Voltage isBetween A-Phase and B-Phasewith Polarity at A-Phase.

Form 2 and 4Invent a load:A-phase has 1200 watts. B-phase has 1800 watts.A-B phase has 3600 watts.

1200/120=10 amps1800/120=15 amps3600/240=15 amps6600 watts total

Ia = 10+15 = 25 ampsIb = 15+15 = 30 amps

Form 2 and 4Remember current coils are ½ and Potential is Eba.

25amps/2 x 240 x cos 0º + 30amps/2 x 240 x cos 0º

= 6600 watts

4s vs. 3s (3-Wire 120/240)

Both are commonly used for 120/240 3-Wire.

4s has half current coils. 3s has full current coils. A 4s with 400/5 CTs will

have a multiplier = 80. A 3s with 400/5 CTs will

have a multiplier = 40.

Discussion…

The End