PRACTICAL USE OF VECTORS IN ELECTRIC METERING - June 11, 2024 - Metering

Oct 25, 2026

Uploaded by kopisore

Practical guidance on using vectors and phasors to understand electric metering relationships between voltage and current. It explains that vectors represent both magnitude and direction, and shows how phasor diagrams encode phase using angles in degrees across a 360° cycle. It provides drawing guidelines such as reference placement at zero degrees, open versus closed arrowheads for voltage and current, and labeling by phase. The session connects these concepts to watthour metering via power-factor and phase-angle relationships, including coil placement effects on phase sequence.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages66

Reading Time2 h 46 min

AccessFree to download

Vectors and Phasors in Metering

Basic Metering Relationship (Watts)

What Vectors Represent

Representing Voltage and Current with Lines

Drawing the Phasor (Guidelines)

Time in Degrees

Watthour Metering Theory Review

Vectorially Expected Meter Phasors

Placing Coils in Order (Delta and Wye)

PRACTICAL USE OF VECTORS IN ELECTRIC METERING Prepared by Perry Lawton, TESCO TESCO Metering North Carolina Meter School Advanced Tuesday, June 11, 2024 8:45 AM METERING The most basic statement of metering: Watts = Voltage x Current x Power Factor Mathematically: Watts = V 􀁵 I 􀁵 cos􀁔 What is a Vector? A measurement that takes two numbers to represent. BOTH a magnitude (size) and direction VECTORS OR PHASORS ARE… a Symbolic Representation of the relationship of the voltage and current • Vectors & Vector Diagrams – SIMPLE. Used to Represent Electrical Quantities. – QUICK. Saves time. – Vastly more effective – Also referred to as “Phasors” REPRESENTING VOLTAGE(E) & CURRENT (I) WITH LINES • Vectors all have MAGNITUDE and DIRECTION • Line length can represent MAGNITUDE. • Line with arrowhead in a given direction indicates that quantity’s relationship to anyother quantity being represented. • DIRECTION: Angles between lines take on significance. They represent time (shown in degrees instead of seconds) . DRAWING THE PHASOR General Guidelines – Complete circle (360 Degrees) equal one cycle of the frequency displayed. – One component (Usually Phase A voltage) becomes the reference and is placed at zero degrees. – Use “open” arrowhead on voltage line(s) . – Use “closed”(or filled in) arrowhead on current line(s) . – Label all voltages and currents by phase. – Indicate Phase Rotation (counter-clockwise assumed if not noted) . “TIME” IN DEGREES | 2
1
0
-1
-2 |

Voltage
Degrees

Current lags Voltage

Current

0 30 60 90 120 150 180 210 240 270 300 330 | | | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | | |
CCW
| | Voltage | | | | by 30 degrees. | | Current 30 ° .866 PF tescometering.com 6 6 “T IME” IN D 1 EGREES 1 00 -1 -2 30 Voltage 360 Degrees 270° 180° tescometering.com 0° Ia Va 90° 1 Element V vo lts or Iamps 0 -1 Phase Angle (Degrees) 270° 6 7 WATTHOUR METERING • Watthour meter theory review: – If we apply “V” volts and “I” amps to a meter, and the phase angle between the voltage and current is some angle 􀁔 , the meter speed will be proportional to: Watts = V 􀁵 I 􀁵 cos􀁔 VECTORIALLY V EXPECTED METER PHASORS (at Power Factor = 1, ABC Phase Sequence) 180° 0° Ia Va 90° 1 Element 270° 270° Ic 0° Ia Va Ia Va 90° 1½ Element 90° 1 Element PLACING COILS IN ORDER 120o Delta Connection A O 120o Wye Connection A 120o C O C Coils connected together and placed on an alternator in order O OA, OB, and OC (Changing Coil order changes Sequence) B

FAQs

What is the fundamental relationship used in metering discussed here?

The document states Watts = Voltage x Current x Power Factor, and expresses it as Watts = V × I × cos(φ).

How do vectors (phasors) represent voltage and current?

Vectors represent a measurement using both magnitude (size) and direction. In diagrams, line length encodes magnitude, and angles encode phase relationships over time in degrees.

What drawing guidelines are given for creating a phasor diagram?

Use a complete 360° circle for one cycle, place one component (typically Phase A voltage) at zero degrees, use open arrowheads for voltage lines and closed arrowheads for current lines, label each voltage/current by phase, and indicate phase rotation.

Oct 25, 2026

Uploaded by kopisore