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Others Waveform Distortion (G1: DC OFFSET (Effects in alternating networks…

- - - - When the end‐use of the electricity requires an AC voltage at a frequency other than at the network (fundamental) frequency (e.g. VSD and Cycloconverter)
      - When the PWM converters on the network side has no synchronism with the network frequency (the harmonics of the modulation frequency will be interharmonics)
      - Switched mode power supply for rectification
- - - - Introduction of harmonic and non-harmonic frequencies
        
        These frequencies are in the radio frequency range, that cause negative operational effects, such as signal interference introduced into logic and communication circuits
      - May overload the electromagnetic interference filters and other similar high-frequency sensitive capacitive circuits
    - - Isolation of the critical and sensitive equipment from the source of the power quality problem
- - - - Switching Activities
        
        Tap Changing on Transformers
        
        Capacitor bank switching
        
        Opening and closing
        
        Re-closing operations
      - Lighting Strides
      - Loose of connections in Distribution system that result in arcing, Accidents, human error, animal and bad weather
    - - Unusual equipment damage due to insulation failures or flash-over
        
        Damage to electronic components
        
        Total failure, lockup or misoperation of computers or micro-processor based equipment.
- - - - Permanent in nature and require manual intervention for restoration.
      - They are specific power system phenomena and have no relation to the usage of the term "outage"
      - Interruption has no relation to reliability or other continuity of service statistics
      - Caused by permanent faults due to storms, trees striking lines or poles, utility or customer equipment failure in the power system or miscoordination of protection devices
    - - Short Interruption - Less than 0.10 per unit
      - Sustained interruption – 0.0 pu
    - - Short Interruption - ½ cycle to 1 minute
      - Sustained interruption - More than 1 minute
    - - Reduce incidents of system faults (i.e. arrester installation, feeder inspections, tree trimming and animal guards)
      - Limit the number of affected customers interrupted (i.e. single-phase reclosers and/or extra downstream reclosers)
      - Fast reclosing (i.e. Uninterruptible Power Supply (UPS), Back-up generator or Self-generation)
  - - - Due to heavily loaded circuits that lead to considerable voltage drop, switching on a large load or group of loads, or a capacitor bank switching off.
      - IEEE 1159: The decrease in the AC voltage (RMS), typically to 80% - 90% of nominal, at the power frequency for a period of time greater than 1 minute
    - - overheating
      - malfunction
      - premature failure and shut down, especially for motors
    - - motors run hotter than normal and fail prematurely
      - dim incandescent lighting and batteries fail to recharge properly
    - - Reducing the system impedance
      - Improving the voltage profile
      - Reducing the line current
  - - - According to IEEE as an increase in the AC voltage (RMS), typically to 110% - 120% of nominal, at the power frequency for duration longer than 1 minute
      - According to IEC 60071-1, overvoltage is any voltage between one phase conductor and earth or between phase conductors having a peak value exceeding the corresponding peak of the highest voltage for equipment
    - - Internal origin – produced from phenomena related to system operation and in general due to abrupt variations of system conditions
      - External origin – due to atmospheric electricity
    - - switching off a large load
      - capacitor switching
      - dropping of load
      - mis-setting of voltage taps on transformers
    - - For surge arrester selection
      - For the design of both the internal insulation of equipment and the external insulation
    - - Adjusting transformers to the correct tap setting
      - Manually or automatically switching off excess capacitor banks during light load or off peak hours
- - - - erratic operations of emergency generators or unstable power frequency sources
      - single generator or an inverter system not connected to the utility grid
    - - confuse logic systems and affect the operating speed of rotating machinery
      - it causes large power failure in the utility side
  - - - mix of reserve generation and uninterruptible loads alleviate excursions
      - active power reduction depending on frequency
- - - - connected in parallel with inductive loads in order to compensate for the power factor of the installation
      - produces a voltage step proportional to the reactive power capacity of the capacitor bank and inversely proportional to the short-circuit capacity of the point of connection
  - - - Flicker affects our brain reaction and impairs vision, leading to discomfort and deterioration in work quality
      - Flicker can affect the production environment by causing personnel fatigue and lower work concentration levels
    - - Synchronous Motors and Generators
        
        Increase in losses
        
        Premature wear of rotors
        
        Changes in torque and power
        
        Hunting
      - Induction Motors
        
        cause changes in torque and slip and affect the production process
        
        result to excessive vibration, reducing mechanical strength and shortening the motor service life
    - - Other devices could malfunction and have reduced efficiency
        
        Computerized or automatic machines to produce defective parts
        
        Unwanted triggering of UPS units to switch to battery
        
        Security system malfunction
        
        Testing equipment to give inaccurate data
        
        Nuisance tripping due to misoperation of relays and contactors
        
        Inconsistency of motor speed
    - - have lower operational efficiency
    - - can reduce both the useful life and the operational efficiency of an electrolyzer equipment
      - elements of the high-current supply line can become significantly degraded, thereby increasing maintenance and/or repair costs
    - - a decrease in power factor and the generation of non-characteristic harmonics and interharmonics
      - commutation failure and damage to system components.