Three-Phase Measurement for Power Calculations

Question 1

What is the use of a PQA?

Answer 1

To evaluate the quantity and quality of power.

Question 2

Apart from measuring current and voltage, what does a typical PQA detect?

Answer 2

• Dips;
• Swells;
• Fast transients;
• Harmonics;
• Power factor;
• Other parameters.

Question 3

How many leads can a PQA have?

Answer 3

3 to 9.

Question 4

How do PQAs fit all of the information on their small screens?

Answer 4

With many pages, you can scroll through the info.

Question 5

When can a single phase PQA be used in a 3 phase circuit?

Answer 5

Only in a balanced circuit.

Question 6

What does the V/A/Hz screen typically display?

Answer 6

Volts (Phase,line,peak);

Amps (Line,peak);

Frequency;

Crest Factor (Volts, Amps).

Question 7

What crest factor indicates no waveform distortion? What indicates high distortion?

Answer 7

1.41;

above 1.8.

Question 8

On the power and energy screen are there polarity indicators for different kVAr readings?

Answer 8

Yes, different meters may show them differently.

Question 9

What are some additional screens one may encounter in a 3 Φ PQA?

Answer 9

• Energy loss calculator;
• Energy loss meter;
• Transients waveform;
• Phasor screen.

Question 10

What is a crest factor?

Answer 10

The peak to rms ratio.

Question 11

How is a 9 lead PQA connected to a wye load?

Answer 11

1. Place current clamps on Phase A, B, C and N.
2. Make voltage connections in order (G=>N=>A=>B=>C).