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Power Quality Issues.pptx
- 1. Sharad Institute ofTechnology, College of Engineering, Yadrav Electrical Engineering Department Presented By: Ms. Patil P. B. Ass. Professor Topic: Power Quality Issues
- 2. Power Quality Issues a.Short duration voltage variation 1) Voltage Sag 2) Voltage Swell 3) Voltage Imbalance Fluctuations 4) Interruption 5) Voltage Spikes b. Long duration voltage variation 1) Overvoltage 2) Under voltage c. Harmonic Distortion Content:
- 3. a. A sagis decrease to between 0.1& 0.9 p.u. in rms voltage or current at the power frequency for duration from 0.5 cycle to 1 min. b. Voltage Sag is also known as Voltage dip. c. Causes: 1. Electric motor draws heavy current at starting 2. Line to ground fault 3. Various accidents in power lines 4. Due to excessive loads d. Voltage Sag Occurs at: 1. Utility System 2. Inside industrial plant 1. VOLTAGE SAG
- 4. e. Effect ofVoltage Sag On Commercial Installation: 1. Flickering Of Light 2. Tripping Of MCB 3. PLC of escalator may drop off
- 5. 1. A swellis defined as an increase to between 1.1 & 1.8 p.u. in rms voltage or current at the power frequency for duration from 0.5 cycle to 1.0 min. 2. The voltage swell is mainly due to Start/stop of heavy loads, badly dimensioned power sources, badly regulated transformers during off peak hours. 2. VOLTAGE SWELL:
- 6. 1. Loads thatcan exhibit continuous, rapid variations in the load current magnitude can cause voltage variations that are often referred as flicker, 2. Effects of Voltage Fluctuations a. Hardware failure b. Crashes in PLC 3. Causes Of Voltage Fluctuations a. Oscillating Load b. Loads with continuous variation in current 3. VOLTAGE FLUCTUATIONS:
- 7. A notchis a condition when the magnitude of voltage decreases towards zero for a short period of time (usually in microseconds). Duration: Microseconds Causes: Utility switching operations, starting and stopping equipment or machinery, static discharges, lightning Effect: Processing errors, data loss, burned circuit boards 4.Notch
- 8. Description: Powerquality noise is unwanted high-frequency electrical signals that can disrupt equipment. Duration: Sporadic Causes: Electromagnetic interference: from appliances, microwave and radar transmissions; from radio and TV broadcasts, arc welding, heaters; from laser printers, thermostats, loose wiring; or from improper grounding. Effect: Disturbs sensitive electronic equipment, but is usually not destructive. It can cause processing errors and data loss. 5.Noise
- 9. A voltage interruptionis a significant drop in voltage, or a complete loss of voltage. According to duration of occurrence, there are two types of interruptions Momentary Interruption Description: Very short planned or accidental power loss Duration: Milliseconds to second or two Causes: Switching operations attempting to isolate an electrical problem and maintain power to your area Effect: Equipment trips off, programming is lost, or disc drive crashes 6.Interruption
- 10. Long Term Interruption Description: Planned or accidental total loss of power in a localized area of community Duration: Over 2 minutes Causes: Equipment failure, weather, animals, human error (auto accidents, kites, etc.) Effect: Systems shut down
- 11. 1. An undervoltage is a decrease in the rms ac voltage to less than 90% at the power frequency for a duration longer than I min. 2. Under voltage & Overvoltage comes under long duration Voltage variations. 3. An Overvoltage is an increase in the rms ac voltage greater than 10% at the power frequency for a duration longer than 1 min. 4.Causes a. Power System Faults b. Equipment Failure c. Control Malfunction d. Loose Connection 7. Over-Voltage & Under-Voltage:
- 12. Description: Analteration of the pure sine wave (sine wave distortion), due to non-linear loads, on the power supply Duration: Sporadic Causes: Non-linear loads Effect: Causes motors, transformers and wiring to overheat 8. Harmonic Distortion:
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