Harmonics has effect on measuring instruments in various ways
1. Error: Measuring instruments are calibrated on purely sinusoidal alternating current but they are used on a distorted electricity supply. This introduces error in measurement.
2. Sign of error: Sign of error depends on the magnitude and the direction of the harmonic power.
3. Harmonic torque: Torque produced by harmonics greatly affects operation of instruments.
4. Any DC power supplied to or generated by the customer will cause an error proportional to the harmonic-fundamental power ratio, with the error sign related to the direction of power flow.
5. Harmonic voltages or currents not only produce torques, but also degrade the capability of a meter to measure fundamental frequency power.
6. The kilowatt-hour meter, based on the Ferraris (eddy current) motor principle, show generally appreciably high readings with a consumer generating harmonics through thyristor-controlled variable speed equipment particularly where even harmonics and DC are involved. By this way, consumers that generate harmonics are automatically penalized by higher apparent electricity consumption. This may well offset the supply authority’s additional losses. It is therefore in the consumer’s own interest to reduce harmonic generation to the greatest possible extent.
7. There is no proof or evidence that the reading of kVA demand meters is affected by network harmonics.
8. KW demand meters operating on the time interval Ferraris motor principle show high reading in presence of harmonics.
9. Harmonics create problems in measurement of VAR values in power networks as VAR is a quantity defined with respect to sinusoidal wave-forms.
10. Absolute average and peak responding meters which are calibrated in RMS are not suitable in the presence of harmonic distortion.
1. Error: Measuring instruments are calibrated on purely sinusoidal alternating current but they are used on a distorted electricity supply. This introduces error in measurement.
2. Sign of error: Sign of error depends on the magnitude and the direction of the harmonic power.
3. Harmonic torque: Torque produced by harmonics greatly affects operation of instruments.
4. Any DC power supplied to or generated by the customer will cause an error proportional to the harmonic-fundamental power ratio, with the error sign related to the direction of power flow.
5. Harmonic voltages or currents not only produce torques, but also degrade the capability of a meter to measure fundamental frequency power.
6. The kilowatt-hour meter, based on the Ferraris (eddy current) motor principle, show generally appreciably high readings with a consumer generating harmonics through thyristor-controlled variable speed equipment particularly where even harmonics and DC are involved. By this way, consumers that generate harmonics are automatically penalized by higher apparent electricity consumption. This may well offset the supply authority’s additional losses. It is therefore in the consumer’s own interest to reduce harmonic generation to the greatest possible extent.
7. There is no proof or evidence that the reading of kVA demand meters is affected by network harmonics.
8. KW demand meters operating on the time interval Ferraris motor principle show high reading in presence of harmonics.
9. Harmonics create problems in measurement of VAR values in power networks as VAR is a quantity defined with respect to sinusoidal wave-forms.
10. Absolute average and peak responding meters which are calibrated in RMS are not suitable in the presence of harmonic distortion.