Study on the Quality of the Mains Power of Atomic Energy Research

Establishment

Presented by Md. Khalid Hossain

Scientific Officer Institute of Electronics

Atomic Energy Research Establishment Bangladesh Atomic Energy Commission , Dhaka-1349

July 15, 2014

Outline

• Objectives

• What is Mains Power Quality ?

• Parameters of Mains Power

• What is Total Harmonics Distortion ?

• Effect of THD on Load

• HA1600 Power & Harmonics Analyzer

• Result & Discussion

• Conclusion

Objectives

• Analysis of power quality of AC distribution systems

• Effect on power regulation and consumption

• Effect on sophisticated scientific instruments

• Effect of Voltage variation on load

What is Mains Power Quality ?

• The stability of the voltage and frequency supplied to customers varies among countries and regions. "Power quality" is a term describing the degree of deviation from the nominal supply voltage and frequency.

• Power quality determines the fitness of electrical power to consumer devices.

Parameters of Mains Power

• There are many parameter of mains power like Watts, VA, Volts rms, Volts peak, Amps rms, Amps peak, Crest factors, THD, Power factor, Frequency.

• Volts rms: The RMS value is

the square root of the mean (average) value of the squared function of the instantaneous values. The symbols used for defining an RMS value are VRMS or IRMS. The term RMS, ONLY refers to time-varying sinusoidal voltages, currents or complex waveforms.

Power Factor

• In AC circuits, the power factor is the ratio of the real power that is used to do work and the apparent power that is supplied to the circuit.

• The power factor can get values in the range from 0 to 1.

• When all the power is reactive power with no real power (usually inductive load) - the power factor is 0.

• When all the power is real power with no reactive power (resistive load) - the power factor is 1.

What is Crest Factor

• The crest factor is the ratio of peak value to RMS value of waveform as shown in below figure. This ratio is also called to peak-to-RMS ratio. The crest factor is expressed as follows: Crest Factor (peak-to-RMS ratio)= (peak value)/(RMS value)

Harmonics Harmonics are voltages or currents that operate at a frequency that is an integer (whole-number) multiple of the fundamental frequency. So given a 50Hz fundamental waveform, this means a 2nd harmonic frequency would be 100Hz (2 x 50Hz), a 3rd harmonic would be 150Hz (3 x 50Hz), a 5th at 250Hz, a 7th at 350Hz and so on.

Complex Waveforms Due To Harmonics

The total harmonic distortion (THD)

• The total harmonic distortion, or THD, of a signal is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency

Effect of THD on Load

• Lesser THD allows the components in a loudspeaker, amplifier or microphone or other equipment to produce a more accurate reproduction by reducing harmonics added by electronics and audio media. A THD rating < 1% is considered to be in high-fidelity and inaudible to the human ear.

HA1600 Power & Harmonics Analyzer

• The HA1600 is a high speed, high accuracy AC power analyser for single phase supplies of up to 16 Amps rms.

• The supply to be measured is connected via a dedicated input cable independently of the supply to the instrument. The output to the load is via a front panel mounted 'standard' mains connector.

• The HA1600 can measure Watts, VA, Volts rms, Volts peak, Amps rms, Amps peak, Crest factors, THD, Power factor, Frequency and Inrush current.

• The large display can show multiple parameters simultaneously along with graphical representations of voltage and current waveforms.

• Compliance-quality harmonics analyser The HA1600 has been designed to make harmonics measurements both quick and simple. It measures harmonics from the 1st to the 40th and updates the display in real time.

Specification

MAINS ANALYSER • Measurement Circuit: Single

Phase with standard mains connector.

• Current Rating: 16A rms • Voltage Ranges: 115V (± 200V pk)

and 230V (± 400V pk). • Current Ranges: ± 24mA pk to ±

400A pk in fifteen 2:1 ranges. • Frequency Range: 43 – 67 Hz. • Sampling Rate: 300 points per

cycle. • Basic Accuracy: Better than 0.2%

±1mA, up to 16A. • Measured Parameters: Vrms,

Vpk, Arms, Apk, Crest factors, THD, W, VA, Power factor, Frequency, Peak Inrush current.

HARMONICS ANALYSER • Measurements: 1st harmonic to

40th harmonic.

• Transform Windows: Continuous 4, 10, 12 or 16 cycle Discrete Fourier Transforms.

• Basic Accuracy: Better than 5% of limit or 0.2% of selected range (whichever is the greater) ±1mA.

VOLTAGE FLUCTUATIONS & FLICKER METER

Measurements: Voltage fluctuations dc, d(t) and dmax and flicker Pst and Plt

Current Rating: 16A rms continuous

Voltage Ranges: 115V (± 200V pk) and 230V (± 400V pk).

Fluctuation Range: 25% max (relative to nominal voltage).

Flickermeter Range:

Voltage change up to 20% (sinewave change) or 10% (low repetition

rate

rectangular change) relative to AGC level.

Equivalent to 6400 pu on 8.8 Hz sinewave.

Flickermeter AGC: Up to ±5%.

Flickermeter

Accuracy: Better than 5% for Pst range 0·7 to 10·0.

Frequency Range: 50Hz (operates over 43 – 67 Hz).

Report Printing:

Tabular listing of voltage variations, Pst classifier and Pst in each Plt

interval.

Power Meter View

The Power Meter view gives a continuously updated display of the major parameters of the supply voltage and load current, together with an instantaneous summary of whether the supply and load meet the limits of the harmonics standard.

Waveform Graph View • The Waveform Graph display

(which is the default display at instrument switch on) can be selected by pressing the WAVE key whenever the green VIEW lamp is lit.

• At the top of the display the scaling for both voltage and current are given. There are 8 divisions vertically, thus 100mA/div is the scaling shown if the ± 400mA peak range has been selected on the set-up screen. In auto-range mode (the default condition) the most sensitive range that gives an in-range display is automatically selected.

Waveform Graph Set-up

• With the Waveform Graph view displayed, pressing SET-UP shows the Waveform Graph set-up screen.

Harmonics View

• With the green VIEW lamp lit, press the HARMONICS key to display the Harmonics view. The default display is a current harmonics histogram.

• The horizontal scale is marked with the harmonic number. Odd harmonics & limits are shown as wide bars and even harmonics & limits are shown as narrow bars. The fundamental is shown to the left of the second harmonic as a wide bar and the DC component is shown to the left of the fundamental as a narrow bar.

Display Format – Tables

• This table lists all odd and even harmonics up to the 40th in two groups on a single page: the left-hand group has the fundamental and all the odd harmonics up to the 39th, the right-hand group lists the even harmonics 2nd to 40th.

Test Control View

• With the green VIEW lamp lit, press

the TEST key to display the Test Control view. This display sets the operating mode of the instrument to Harmonics, Voltage Variations & Flicker, or Peak Inrush Current and allows the details of all the measurements to be configured. The contents of the Test Control view change depending on which mode is selected; the following paragraphs describe the Test Control facilities available in the Harmonics mode. The other modes are described in their own chapters.