Module 1 Flashcards
Power and voltage quality
power quality-refers to the quality of electric power supply in terms of its consistency ,reliability,purity etc..
it measures how well the power supply meets the requirements of the connected electrical equipments
Pq mainly deals with :
-countinuity of supply
-quality of voltage
sine wave should be pure
voltage should be balance in all 3 phases
causes:
voltage fluctuation,harmonics,transients
voltage quality refers to the quality of voltage waveform including it’s amplitude,frequency and waveform distortion
it lead to problems such as :
-equipment malfunction
-reduced efficiency
-increased energy consumption
causes:
-poor grounding
-power factor issues
-voltage regulation problems
Major reasons for increased concerns of power quality
-Newer generation load equipment-(microprocessor based control and electronic devices is more sensitive to power quality variations.
-Application of devices such as high efficiency and adjustable speed motor drives and shunt capacitor for power factor correction to reduce losses resulted in increasing harmonic levels on power system
-End users have an increased awareness of power quality issues-demanding better quality
-Many things are now interconnected in a network integrating processes means that the failure of any components means much more consequence
power quality problems
-any problem related to voltage ,current or frequency deviation results in mal
operation of customer equipment
-it causes deterioration of various sensitive and electronic equipment
-sufficient deviation in power supply cause equipment failure
causes of poor power quality
Voltage sags and dips: These are short-term drops in voltage that can cause lights to flicker or equipment to shut down.
Voltage swells: These are short-term increases in voltage that can damage equipment.
Harmonics: Harmonics are frequencies that are multiples of the fundamental frequency of the power system. When there are too many harmonics, they can cause interference and damage to sensitive electronic equipment.
Transients: Transients are short-term spikes in voltage or current that can damage equipment.
Unbalanced loads: When loads are not balanced across all three phases of a three-phase power system, it can cause voltage imbalances and other power quality issues.
Power factor: Power factor is a measure of how efficiently electrical power is being used. Poor power factor can cause a variety of issues, including increased energy costs and equipment damage.
Electrical noise: Electrical noise is unwanted electrical signals that can cause interference and damage to sensitive equipment.
Voltage and frequency variations: Fluctuations in voltage and frequency can cause equipment to malfunction or fail.
● Currents from lightning strokes passing through the power system cause
high-impulse voltages that frequently flash over insulation and lead to other
phenomena, such as short circuits.
● Distorted currents from harmonic-producing loads also distort the voltage as they pass through the system impedance. Thus a distorted voltage is
presented to other end users.
Importance of power quality
Equipment performance: Poor power quality can cause equipment to malfunction, fail prematurely, or operate inefficiently. This can result in increased downtime, maintenance costs, and reduced productivity.
Safety: Electrical equipment can pose a safety hazard if it is not functioning properly due to poor power quality. For example, electrical shocks, fires, or explosions can occur if the voltage is too high or too low.
Energy efficiency: Poor power quality can result in energy losses due to inefficient operation of equipment, which can increase energy costs.
Compliance with regulations: Many industries are subject to regulations that require certain levels of power quality to be maintained. Failure to comply with these regulations can result in fines or other penalties.
Customer satisfaction: Poor power quality can also impact the satisfaction of customers who rely on electrical services. For example, if power outages or voltage fluctuations occur frequently, customers may be dissatisfied with the service provided.
Hidden cost ,maintanence,damaged product and lost production
in many cases the optimal solution is to make a sensitive electronic device less sensitive to power quality variations
How power quality is quantified?
it is difficult to quantify PQ
the ultimate measure of pq is measured by the quality and performance of end user equipment
Power quality evaluation
General steps that are often required in a power quality investigation, along
with the major considerations that must be addressed at each step are.
identify problem category
voltage regulation/unbalance,voltage sags/interruption,flicker,transients,harmonic distortion
problem characterization
measurement/data collection-causes,characterestics,equipment impact
identify range of solution
utility transmission system,utility distribution system,end-use customer interface,end-use customer system,equipment design/specifications
evaluate solution
modelling/analysis procedure
