Power calculation disagreement

Good afternoon,

I tried what I thought would be simple power calculations, but the calculations are not balancing.  It seems that I'm doing something fundamentally incorrect.  Here's a hypothetical situation that illustrates the problem.

There is a new 120/208 panel that has only one 2-pole breaker installed.  The load is 208 and the neutral is not used by the load.  The panel power meter shows line currents of 10, 10, 0.  The power factor is .90.  With the above readings, I believe the power for the panel (which represents only the one load) would be:

Average of line currents * line voltage * power factor * sqrt(3)

6.67 * 208 * .9 * 1.732 = 2,162 Watts

Then I go out to the field with my multi-meter and calculate power at the load:

Line current * line voltage * power factor (assumed to be same as panel)

10 * 208 * .9 = 1,872 Watts.

Why do I calculate ~15% lower power at the load?

Thanks,

Paul


asked 6/30/2018
PBerry2
PBerry

0 Answers

Your Answer

In order to provide an answer to this question, you must Login

I am flagging this question because...




10 inform moderator flags remaining

I am deleting this question because...




I am flagging this answer because...




10 inform moderator flags remaining

Flagging a Post

You have already flagged this post. Clicking "Remove Flag" below will remove your flag, thus reducing the count by one as well.

I am deleting this answer because...





Fault Calculation - Symmetrical Components

For unbalance conditions the calculation of fault currents is more complex. One method of dealing with this is symmetrical components. Using symmetrical...

Motor Insulation

Insulation on a motor prevents interconnection of windings and the winding to earth.  When looking at motors, it is important to understand how the insulation...

Autonomous Vehicle Challenge

Two driverless and solar power vans have departed from Italy on their way to China via the silk road. During the 13,000 kM trip the vans will drive themselves...

Medium Voltage Switchgear Room Design Guide

Many medium voltage (MV) indoor switchgear rooms  exist worldwide. The complexity of these rooms varies considerably depending on location, function and...

Large Hadron Collider

The 27 km, Euro 6 billion  Collider lies on the border between France and Switzerland, took nearly 30 years to complete.  Some of the lofty goals for the...

IEC Reference Designations

The IEC publishes a series of documents and rules governing the preparation of documents, drawings and the referencing of equipment.   Depending on country...

How to Check a Circuit is Dead

If you want to check a circuit is dead (not live), you should always use the three point method. First check a known live circuit, then check the dead...

Random Numbers

Using laser optical pulses the random number generator utilizes the time between arrival of random photos to generate the numbers, ensuring true accuracy...

Earth Electrode Resistance

Earthing of electrical systems is essential for the correct functioning and the protecting of life and equipment in the event of faults.  The earth electrode...

IEEE Winds of Change

IEEE TV has a part series of videos on wind power and it's implication. For a really good overview to the technologies and issues around wind power, these...

Our website uses cookies so that we can provide a better experience.
To learn more about what cookies are and how to manage them visit AboutCookies.org