Transient Study in India –Sachu Technologies

Sachu Technologies offering Transients study to identify typically caused by lightning, electrostatic discharges, load switching or faulty wiring.

Transients (fast disturbances): Rapid change in the sine wave that occurs in both voltage and current waveforms. Caused by switching devices, start- and stop of high power equipment. They can vary widely from twice the normal voltage to several thousand volts and last from less than a microsecond up to a few hundredths of a second. Rapid change in the sine wave that occurs in both voltage and current waveforms. Caused by switching devices, start- and stop of high power equipment. They can vary widely from twice the normal voltage to sevTransients are power quality disturbances that involve destructive high magnitudes of current and voltage or even both. It may reach thousands of volts and amps even in low voltage systems. However, such phenomena only exist in a very short duration from less than 50 nanoseconds to as long as 50 milliseconds. This is the shortest among PQ problems, hence, its name. Transients usually include abnormal frequencies, which could reach to as high as 5 MHz.eral thousand volts and last from less than a microsecond up to a few hundredths of a second.

Sources of Transients

1. Lightning Strikes
2. Switching activities
3. Opening and closing of disconnects on energized lines
4. Capacitor bank switching
5. Reclosing operations
6. Tap changing on transformers
7. Loose connections in the distribution system that results to arcing
8. Accidents, human error, animals and bad weather conditions
9. Neighboring facilities

Effects of Transients

1. Electronic Equipment
2. Equipment will malfunction and produces corrupted results
3. Improper specification and installation of TVSS can aggravate the failures
4. Efficiency of electronic devices will be reduced

Motors

1. Transients will make motors run at higher temperatures
2. Result in micro-jogging leading to motor vibration, excessive heat and noise
3. Degrades the insulation of the motor winding resulting to equipment failure.
4. Increases the motor’s losses (hysteresis) and its operating temperature

Lights

1. Fluorescent bulb and ballast failure
2. Appearance of black rings at the fluorescent tube ends (indicator of transients)
3. Premature filament damage leading to failure of the incandescent light.

Electrical Equipment

1. Transients degrade the contacting surfaces of circuit breakers and switches
2. Nuisance tripping of breakers due to false activation to a non-existent current demand
3. Reduce transformer efficiency because of increased hysteresis losses

Damages due to such PQ problems are uncommon as compared to voltage sags and interruptions, but when it does occur it is more destructive. To protect against transients, end-users may use Transient Voltage Surge Suppressors (TVSS), while utilities install surge arresters.

Furthermore, transients are classified as:

1. Impulsive
2. Oscillatory

Transients Synopsis

Magnitude: Several thousands of volts and amps

Duration: <50 ns to 50 ms

Source: Lightning and switching activities

Symptoms: Electronic component damage

Occurrence: Low

Transients are sudden but significant deviations from normal voltage or current levels. Transients typically last from 200 millionths of a second to half a second. Transients are typically caused by lightning, electrostatic discharges, load switching or faulty wiring. The sampling rate is a constant 256 samples per cycle. When a transient capture is started, each sample is compared to the sample from the preceding cycle. The preceding cycle defines the mid-point of a virtual tube and is used as reference. As soon as a sample is outside the envelope, it is treated as a triggering event; the representation of the transient is then captured by the device. The cycle preceding the event and the three following cycles are saved to memory.

The half-width of the virtual envelope for the voltage and current is equal to the threshold programmed in the Transient mode of the configuration

Power Flow study involves measurement of

Active Power (KW), all phases & equivalent

1. Apparent Power (KVA) equivalent
2. Reactive Power (KVAr)
3. Power Factor (pf)
4. Currents , all phases and equivalent
5. Voltages , Line to Line and equivalent
6. THDS (V) and THD (I)
7. Dominant Harmonics Optimize component or circuit loading
8. Develop practical bus voltage profiles
9. Identify real and reactive power flow
10. Minimize kW and kVar losses
11. Develop equipment specification guidelines
12. Identify proper transformer tap settings

The most important information obtained from the load flow analysis is the voltage profile of the system. If voltage varies greatly over the system, large reactive flows will result. This, in turn, will lead to increased real power losses and, in extreme cases, an increased likelihood of voltage collapse. When a particular bus has an unacceptably low voltage, the usual practice is to install capacitor banks in order to provide reactive compensation to the load. Load flow studies are used to determine how much reactive compensation should be applied at a bus, to bring its voltage up to an appropriate level. If new lines (or additional transformers) are to be installed, to reinforce the system, a power flow study will show how it will relieve overloads on adjacent lines. An inefficient or unbalanced load can also cause unpredictable behavior in your localized power grid, increasing the risk of equipment damage and unplanned outages.

It shall help to determine how the system will operate in normal cycle and emergency conditions and during different parts of day or Week. P.F compensation system, Automatic or fixed installed in the network are also checked for their effect in the network.

Load flow analysis has following advantages

1. Helps in future planning and present day operations by showing how the electrical system will perform during normal, emergency and various time slots of day or any period may be week or month as defined by the consumer.
2. It helps in minimizing energy cost by determining the location and size of power factor correction capacitors on each load
3. Helps in determining the proper voltage selection through transformer tap settings so that the correct voltage will be present in the network.
4. Determining the capacity utilization of major Loads.
5. Suggestion for improvement in Network efficiency