Low Power Quality Samples
>Low power quality is called the deviation from the ideal voltage waveform.

Short Term Changes
Voltage drop: The nominal line voltage is between 1% and 90% between 0.5 and 1 minute. The general resources of the voltage drop are the input of the large asynchronous motor or the network malfunctions (phase-to-ground-phase faults).

Voltage Swell: gthe opposite of the voltage drop. The nominal line voltage is reduced from 110% to 180% from 0.5 cycles to 1 minute. General causes of failure; line faults (voltage increase in fault-free phase due to phase-by-fault), switching of large loads, switching of large capacitor banks, faults in distribution transformer exchangers. Voltage peaks are characterized by magnitude and occurrence times. The intensity of the voltage rise is a function of the fault location, system impedance and grounding. In the case of a phase-to-earth fault in a non-grounded system, the phase-to-earth voltage in the non-earthed phase will be 1.73 times the normal.
Interruption: This is less than 10% of the voltage which does not last longer than 60 seconds

KInterruption (Interruption): does not last more than 60 seconds in voltage.

Temporary Events

Impulsive transient: two-way abrupt short changes in voltage or current. They are characterized by rise and fall times. For example, the sudden transient change of 2000V to 1.2 / 50 microseconds increases to 1.2 microseconds and reaches a peak of 2000V, decreasing to half of its peak in 50 microseconds. Causes, lightning drops, inductive loads is the introduction of. If the level of these transient events is high, it will cause the equipment to shut down. By using temporary voltage suppressors such as zener diode, varistor, the effects can be reduced. Because they are high frequency, they can be easily suppressed by resistive loads, do not act much more than their source. The temporal event characteristic of a region within the building may be very different. These distortions can trigger resonant circuits in power systems and may lead to releasing regimes.

Sudden changes (Impulsive transient): Two-way sudden short changes in voltage or current. They are characterized by rise and fall times. For example, the sudden transient change of 2000V to 1.2 / 50 microseconds increases to 1.2 microseconds and reaches a peak of 2000V, decreasing to half of its peak in 50 microseconds. Causes, lightning drops, inductive loads is the introduction of. If the level of these transient events is high, it will cause the equipment to shut down. By using temporary voltage suppressors such as zener diode, varistor, the effects can be reduced. Because they are high frequency, they can be easily suppressed by resistive loads, do not act much more than their source. The temporal event characteristic of a region within the building may be very different. These distortions can trigger resonant circuits in power systems and may lead to releasing regimes.

Oscillatory transient changes:): two-way sudden short changes in voltage or current. They are classified as high, low and medium frequency variations according to their frequencies. The oscillations greater than 500 kHz are classified as high-friction. These are the changes that occurred after the anisalinm. They are medium frequencies between 5-500kHz. In sequence capacitor switching, medium-frequency oscillatory changes are present in the current. 5khz is called low frequency changes.

Voltage Fluctuations

Voltage fluctuations: less than 5% of the line voltage. Loads of continuous and rapid change in current size, called flicker, cause voltage fluctuations. The voltage fluctuations are the reaction of the three systems to the loads, and the light flicker is the visible reaction of the luminosity system in human eyes.

Voltage Imbalance

Imbalance:: 3-phase voltage is different from each other. Voltage imbalance is the ratio of negative or zero component to positive component. Negative or zero stress components result from unbalanced loads causing unbalanced currents to be drawn in power systems.r.