Bad Power Quality arise from power system's interaction with power surge and harmonic distortion. If a power system is susceptible at a point possibilities of power quality tripping, resonance and CMV failure are limitless and are as dynamic as the fluctuation in the power system impedance along with its load demand and harmonics distortions. An electrical power system at the threshold of a harmonic resonance condition is like a stormy sea. Charged with voltage fluctuations and power surge. Unpredictable and could strike at any moment. Cause vast damage in plant and machineries. Disperse as fast as it arrive. The good news is, it could be avoided. The success of a comprehensive power quality solution in mitigating electromagnetic transients depends on the appropriateness of the power quality analysis. And the implemented power quality solution will sustainably provide a stable and improved quality of power at the susceptible point in the electrical power system.
With Encon, you are 100% certain about the success of your plant's power quality solution project. Followings are example of diverse power quality problem those we resolve routinely by appropriately tuning our harmonic filters. Power quality resonance and common mode voltage (CMV) problems are unique. We frequently encounter fresh problem and new challenges from industries. Over the past 25 years, our 350 plus corporate clients, have relied on our comprehensive power quality solutions. Over 85% of our clients implement it repeatedly across their plant locations and also with new project from the drawing-board stage.
1. The most common power quality problem is equipment tripping due to momentary voltage fluctuation/ sag and the resulting electronic card failure with or without software corruption. A power system resonance could originate either from the external grid/ utility or internal power system. Depending upon the magnitude of the resulting voltage sag and power surge, it causes appropriate damage with the plant equipment. The most susceptible are drive electronic, solar inverter, SCADA, HMI, SMPS power supply, hard disk and motherboard. Industrial computers many a times reboot or hang. They fail first. Followed by electrical equipment which blast with a loud boom like Disc Insulator, Lightning Arrester, Current Transformer (CT), Potential transformer (PT), HT Metering Kiosk, Load Break Switch (LBS), HT Circuit Breaker and power line's Coupling Capacitor (used for hot line telephone communication).
If the incidence coincides with an earth fault it would cause a steep voltage sag. The resulting AC ripple could pass through the UPS DC-bus to its output supply. And nothing that the UPS could protect. It could trip or fail the data center server, computer and its components like smps power supply, hard disk and motherboards. The best and time tested power quality solution is super tuned passive harmonic filter. We have implemented this passive solution with over hundreds of installations. Unlike the active harmonic filter passive filter can store energy. A super tuned passive harmonic filter stores sizeable energy and can act like an electrical flywheel. It locks on to the momentary voltage fluctuation/ sag. Provides a momentary ride through. And mitigates the problem that including the resulting equipment damage.
2. A Harmonic rich grid/ utility supply could induce a sudden spurt in Noise and Vibration with major electrical equipment like power transformer, electric arc furnace transformer, circuit breaker, PCC bus bar and large motors. All industries powered from the affected grid get affected. The power system resonance could last momentarily for few seconds or prolong for several minutes. It causes failure in transformer's winding insulation. Its high voltage (HV) winding insulation burns, flashes, blasts or gets dislodged. The OLTC/ OFTC terminals burn or get flashed. The low voltage (LV) winding insulation burns or gets blackened with heavy flash. The motor winding insulation burns or gets blackened in a patch that gets most susceptibility from the electrical harmonic resonance. The PCC bus bar gets overheated visibly red hot. Vibrate audibly loosening its nuts and bolts. Wear out the affected bus bar plates. The primacy of power quality solution here boils down to blocking the power harmonic resonance. The connection point of harmonics filter could be at the immediate upstream from the affected electrical system. It could be at the high voltage grid incomer or at the medium voltage secondary of the grid transformer.
3. Variable Speed Drive (VSD) and Solar inverter create very high frequency current harmonic distortion. In turn, it creates very high frequency voltage harmonic distortion components. Its magnitude depends upon the susceptibility of the electrical power system. As a result it creates a Common Mode Voltage (CMV) across all connected electrical equipment. That passes through bus bars and circuit breakers. It could cause an oscillation in the frequency meter. Eventually it creates an electrical blast. That could explode the circuit breaker/ ACB/ MCCB with a fatal Arc Flash. It also causes a blasting explosion from the live bus bar or equipment terminal to the most susceptible ground path. The CMV problems are elusive. They occur even when harmonics are well within the regulatory norm of IEEE 519. The power quality solution here requires mitigation of high frequency voltage harmonics distortions. That could eliminate the CMV for the affected electrical power system. Encon's super tuned passive harmonic filters have sustainably solved challenging CMV blasts in power intensive industries. That employ lots of variable frequency drives (VFD) and solar inverter.
4. Periodic failure of Capacitor, Inductor, detuned filter and electrical switch gear: Ordinarily, many industry employ power factor (PF) correcting capacitors and detuned harmonic filters. It's done by connecting an inductor (also called series reactor) in series with the PF correcting capacitor. The capacitors could be HV or LV rating. Depending upon the susceptibility of the electrical power system; it could excites a harmonic resonance problem. Its effect could bulge or blast the capacitor, detuning reactor and its feeder switch gear and cable.
5. Cable insulation puncture: An electrical system under a power quality harmonic resonance condition could create massive power surge and fluctuations. That could puncture cables within the affected network. The network cables could be in the high voltage or low voltage power system.
6. Power plant Tripping, Blackout, Damages, and failures: Power quality solution mitigates power plant's tripping and black-out problems due to power quality harmonic resonance. It causes its protective relay to trip due to a combination of faults. These faults could be earth fault (EF), instantaneous non-directional over current (NOC) fault, higher negative phase sequence current (NPS), under voltage (UV), and differential fault in the alternator or power transformer. In-addition, it causes electrical flash or blast in the rotating-diodes assembly with the alternator's exciter circuit.