12 Questions
What is the purpose of a phase advancer?
To supply leading ampere-turns at slip frequency to reduce the lagging power factor kVAR drawn by the induction motor.
What are some advantages of power factor correction?
a) Decreased rating of alternator, transformer, and switchgear (KVA). b) Reduced conductor size. c) Decreased power loss in the system. d) Better voltage regulation. e) Increased system efficiency. f) No penalty in power factor tariff. g) Overall cost reduction.
What is a disadvantage of power factor correction?
Not economical for motors below 150 KW.
How do three-phase transformers contribute to the efficiency of generation and distribution systems?
Three-phase transformers play a crucial role in three-phase AC systems, allowing for efficient power transmission and distribution.
What is the purpose of using synchronous condensers in a power system?
To draw leading current and compensate the lagging reactive component of load current to improve power factor.
How can the power factor be improved using a synchronous machine?
By varying the field excitation of the synchronous machine.
What are the disadvantages of using synchronous condensers for power factor correction?
High cost, high maintenance and operation cost, considerable losses in rotating parts, lower efficiency compared to static capacitors, noise production during operation, not self-starting, and the risk of falling out of synchronism.
How does a phase advancer contribute to improving power factor in a system?
It supplies exciting ampere turns to the rotor circuit at slip frequency, providing flux that improves the power factor.
What is the purpose of a synchronous condenser?
To correct power factor
What are the advantages of power factor correction?
Increased system efficiency, reduced power loss, better voltage regulation, reduced penalties in power factor tariffs
What are phase advancers used for in electrical systems?
To improve the power factor of induction motors
What are the disadvantages of power factor correction?
Increased size of conductors, higher ratings for alternators/transformers/switchgear, increased power loss in the system
Study Notes
Power Factor Correction
- Power factor correction is used to improve the power factor of a system, which is the ratio of active power to apparent power.
- Advantages of power factor correction include:
- Reduced electrical losses and heat in the system
- Improved system efficiency
- Increased system capacity
- Reduced voltage drops
- Improved system reliability
- Disadvantages of power factor correction include:
- Increased cost and complexity
- Possibility of harmonic resonance and oscillations
Phase Advancers
- Phase advancers are used to improve the power factor of a system by shifting the voltage waveform to be more in phase with the current waveform.
- Phase advancers contribute to improving power factor by advancing the voltage waveform, reducing the reactive component of current.
Synchronous Condensers
- Synchronous condensers are synchronous machines (motors or generators) used to improve the power factor of a system.
- The purpose of a synchronous condenser is to provide reactive power compensation, improving the power factor of the system.
- Advantages of using synchronous condensers include:
- Ability to provide both inductive and capacitive reactive power compensation
- Can be used for both leading and lagging power factor correction
- Can be used to regulate system voltage
- Disadvantages of using synchronous condensers include:
- High cost and maintenance requirements
- Complexity of operation and control
- Possibility of self-excitation and oscillations
Three-Phase Transformers
- Three-phase transformers contribute to the efficiency of generation and distribution systems by:
- Allowing for efficient transmission of power over long distances
- Providing isolation and voltage transformation for safe and efficient power distribution
Learn about the benefits of reducing lagging power factor kVAR with leading ampere-turns using a phase advancer, as well as the limitations related to motor size. Explore how power factor correction can decrease ratings of alternators, transformers, and switchgear, reduce conductor size, and minimize power loss in the system.
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