Basic Terminology of Power Quality Part 2

1. Harmonics

Harmonies are sinusoidal voltage/current having frequencies that are integer multiple of fundamental frequency. Harmonics in the system can

• Make relays maloperate
• Increase loss in capacitances, noises
• Telephonic cross talks
• Can cause increase in resonance.

2. Inter Harmonics

The voltage or the current that is not the multiples of power frequencies are called  inter harmonics.

It is caused mainly due to non linear loads which cause overheating of the equipment. By using harmonic filters this can be eliminated.

3. Harmonic Distortion

Presence of higher harmonics makes waveform distorted and causes fundamental waveform distorted.

Waveform Of Harmonic Distortion

4. Immunity (or Disturbance)

The capability of the device to execute without any system degradation in the presence of electromagnetic disturbance is called as immunity.

5. Impulse

A pulse that starts and ends within short duration of time within the rise and fall characteristics and mathematically regarded as the infinite.

6. Isolation

It is the separation of one system from the other system from the undesired influences.

7. Noise

The unnecessary electrical signals that produce unwanted disturbances in the circuits are called as noise.

Waveform Of Noise

8. Nominal Voltage

A nominal value assigned to the system for the purpose of proper functioning is called nominal voltage.

9.Inrush

Large current that is drawn when the machine is initially turned ON.

10. Interruption

An Interruption is defined as decrease in the supply voltage or load current less than the seconds or in other words it the loss of the voltage of the current or voltage for a complete time period.

Waveform Of Interruption

11. Linear Loads

In steady state operation, if voltage and current are same as sinusoidal waveform then called linear loads. Linear loads do not have harmonics in them.

12. Non-Linear Loads

Here current and voltage waveforms are not proportional to each other. They require large inrush current.

13. Notch

The disturbances that is produced in that normal waveform which is lasting less than a half cycle is called as the notch.

14. Power Disturbance

It is the divergence from the fundamental value of the input AC characteristics.

15. Periodic

The voltage or the current is periodic if it exhibits the condition x(t) = x(t + T), where T is the period of the function.

16. Power Factor

It is the ratio of real power to the apparent power, which is product of current and voltages.