Important short questions and answers: Power Quality Monitoring

Power quality Monitoring

1. What are all power quality measuring equipment ?

1.     Wiring and grounding test devices

2.     Multi meters

3.     Oscilloscopes

4.     Disturbance analyzers

5.     Harmonic analyzers and spectrum analyzers

6.     Combination disturbance and harmonic analyzers

7.     Flicker meters

8.     Energy monitors

2. Define spectrum.

A range of frequencies within waves have some specified common characteristic, for example, audio frequency system..

3. Define Harmonic Analyzers

Harmonic analyzers have several capabilities. They capture harmonic waveforms and display them on a screen. They calculate the K factor to derate transformers and the total harmonic distortion (THD) in percent of the fundamental

4. What are the parameters to be monitor for identify the power quality problems?

Power quality encompasses a wide variety of conditions on the power system. Important disturbances can range from very high frequency impulses caused by lightning strokes or current chopping during circuit interruptions to long-term over voltages caused by a regulator tap switching problem.

5. Define expert system.

It is the one of the soft computing method, it is an area of computer since concerned with designing intelligent computer systems, that is exhibit the characteristics we associate with intelligence in human behavior.

6. What are the types of power quality measurement equipment?

1.     Hand held single phase power quality monitors

2.     Portable three phase power quality monitors

3.     Harmonic analyzers

4.     Distortion analyzers

5.     Multi meters

7.  What is meant by power quality monitoring?

Power quality monitoring should be an integral part of the design for high reliability facilities. The monitoring will characterize the performance of the supply system and the performance of power conditioning equipment at the facility, including possible interaction issues with facility loads.

8.  What are the purposes of power quality monitoring system?

a.     Preventive maintenance

b.    Load analysis

c.      Equipment diagnostics

d.     Long time surveys

9.     What are the characteristics of power line monitors?

1.     Portable, rugged, lightweight

2.     Simple to use, with proper training

3.     Designed for long term unattended recording

4.     Definition of line disturbance parameters varies between manufactures

10.                        What is spectrum analyzer?

An instrument used for the analysis and measurement of signals throughout the electromagnetic spectrum. Spectrum analyzers are available for sub audio, audio, and radio frequency measurements, as well as for microwave and optical signal measurements.

11.                        What is tracking generator?

The  tracking  generator  enhances  the  applications  of  spectrum  analyzers.  Its  output

delivers a swept signal whose instantaneous is always equal to the input tuned frequency of

the analyzer.

12. Mention some examples of flicker sources

a.     Arc furnaces

b.     Welding machines

c.      Wind turbines

13. Give an application of capacitive dividers.

1. Capacitive divider network is employed for measurement of very high frequency

components in the voltage level of substation.

2.     Some application requires a special purpose capacitor dividers can be obtained for measurements requiring accurate characterization of transients up to at least 1 Mhz.

14.                        What is the operation of spectrum analyzer?

^Ø   A spectrum analyzer separates the signal into two components: amplitude (displayed vertically) and frequency (displayed horizontally). In some low frequency analyzers, phase information can also be displayed.

^Ø   Low frequency analyzers are some times called as harmonic analyzers.

^Ø   Vertical scale displayed the amplitude and horizontal scale displays the frequency.

15.  What is the use of spectrum analyzer?

A spectrum analyzer can be used for trace of high frequency harmonics.

16.                        Mention the factors that should be considered for selecting the instrument.

1.     Number of channels

2.     Temperature specifications of the instrument

3.     Input voltage range

4.     Ability to measure three phase voltages

17.                        Mention the instruments used for the analysis of non sinusoidal voltage and currents.

1.     Oscilloscope

2.     Spectrum analyzer

3.     Harmonic analyzer

18.  Mention the basic categories of instruments for harmonic analysis.

1.  Simple meters

2.  General purpose spectrum analyzers

3.  Special purpose power system harmonic analyzers

4.  Digital harmonic measuring equipment

5.  Distortion analyzers

6.  Data logger

19.                        Define voltage flicker according to IEEE standard 1159.

Voltage fluctuation is the response of the power system to the varying load and light

flicker is the response of the lighting system as observed by the human eye

20. Define voltage flicker?

According to IEC-868 std. voltage flicker is defined as the perceived variation in light intensity from a lamp as a result of the modulation or fluctuation in the amplitude of the voltage at low frequencies.