Electrical Issues and Power Factor Correction

Common Problems at the Customer Side

• Voltage problems at the customer's end may arise from issues within their electrical facilities
• Examples include loose connections, undersized/overloaded/overextended conductors, and unbalanced single-phase loads
• To resolve these issues, correct the problem and consult an electrical consultant if necessary

Power Factor Correction Capacitors

• Industrial and commercial customers commonly install capacitors to enhance their system's power factor
• However, capacitors can elevate system voltage, possibly causing overvoltages during periods of light load or off-peak hours when continuously switched on
• Solutions involve manually de-energizing capacitors during off-peak periods, or using voltage/power factor-based devices to selectively energize units during specific times of day

Voltage Mismatch

• Some customer equipment, primarily motors, are rated for specific voltage levels (e.g., 220V or 440V)
• Motors can function with supply voltages within a tolerance range (e.g., ±10% of their rating)
• Supply voltages exceeding these ranges, although still permissible, might exceed the operating range of the equipment.
• Solutions for customers include installing special transformers or voltage regulators for the equipment, and for utilities, adjusting source transformer tap settings after evaluating existing customer supply voltages

Voltage Fluctuation

• Fluctuations in voltage are described as random changes normally between 95% and 105% of the nominal value
• Solutions include correcting loose connections, upgrading conductors, and providing separate power sources for the problematic loads

Voltage Swell

• Voltage swell is a sudden increase in voltage exceeding 1.1 pu (per-unit) for durations of less than one minute
• Typical causes include line-to-ground faults and the switching on of large capacitor banks or the sudden dropping of large loads
• Effects of voltage swell include device failure in electronic and computer equipment; shortened equipment lifespan; unwanted relay operations

Voltage Sag/Dip

• Voltage sags (dips) are temporary reductions in voltage, usually lasting less than one minute, characterized by voltage variation between 0.1 to 0.9 of the nominal voltage
• Possible causes include line-to-ground faults, the starting of high-inrush-current equipment (e.g., motors, arc furnaces), and loose connections
• Typical solutions include using larger conductors and transformers, reduced voltage motor starters, and employing constant voltage transformers or UPS systems for sensitive loads

Unbalanced Voltage

• Unbalanced voltage in three-phase systems can lead to overheating of motors and trigger the operation of zero-sequence relays, leading to equipment shutdown
• Causes can include unbalanced secondary loads, loose connections, non-uniform transformer taps, large impedance differences between transformers, de-energized capacitor units, and single-phasing in open-wye/open-delta configurations
• Load balancing and correcting loose connections are common solutions

Overvoltage

• An overvoltage occurs when a voltage measurement surpasses the nominal value for longer than one minute
• Possible causes include high tap settings on distribution transformers, high primary voltages, loose neutral grounding, inappropriate transformer connections, and single phasing issues in open-wye/open-delta systems

Undervoltage

• Undervoltage happens when a voltage is consistently lower than the nominal value for more than a minute
• Potential causes include load shifting issues, problems with connections, transformer tap settings, improper sizing of conductors, and de-energized capacitor banks
• Solving this typically involves adjusting load distribution, repairing connections, adjusting transformer tap settings, and, in some cases, adding capacitors or voltage regulators

Low Primary Supply Voltage

• Low primary supply voltage stems from problems on the primary side of electrical installations: loose connections, excessively long primary lines, insufficiently sized conductors, de-energized substation capacitor banks, faulty power transformers, and malfunctioning voltage regulators
• Addressing the root cause of low voltage is vital

Sample Computations and Formulas

• Methods for calculating voltage imbalance and variation are presented, showcasing formulas and example calculations using measured/given values and nominal voltages

Power Quality Parameters and Limits

• Frequency, typical service voltage levels, voltage waveform distortion (THD), and voltage unbalance are key power quality parameters and their allowable ranges are described

Equipment and Utility Concerns

• Equipment manufacturers focus on the compatibility of equipment, considering tolerance to power disturbances.
• Utility concerns revolve around determining the source and effect of power disturbances, aiming for minimizing disturbances and maintaining the delivery of reliable power within the specified limits

End-User Concerns

• End-users worry about how power disturbances affect their equipment operation and the overall impact on plant operations

Power Quality Problem Definition

• A power quality problem is essentially any power issue affecting voltage, frequency, or current, leading to equipment malfunction or under performance

Electromagnetic Compatibility

• Electromagnetic compatibility (EMC) is defined as the ability of equipment to function correctly in an electromagnetic environment without causing unacceptable disturbance in other devices

Other

• A general overview of the concept of power quality and its importance in overall electrical system performance is provided

This quiz covers common electrical problems that customers may face, including voltage issues and power factor correction. It explores the impact of capacitors on system voltage and provides solutions for managing these challenges. Test your knowledge on troubleshooting and optimizing electrical systems.