Question

1. List any four types of faults that can occur in power transformers?   

2. List any four effects of sustained low power factor on equipment.

3. List any four methods that can be used to improve power factor?

4. List any two economic benefits of power factor correction?

Answer 1

1)Power transformer faults

1. Insulation breakdown between winding and earth
2. Insulation breakdown in between different phases
3. Insulation breakdown in between adjacent turns
4. Transformer core fault

2 ).

A Low P.F. draws a higher internal current and the excessive heat generated will damage and/or shorten equipment life
• Increased reactive loads can reduce output voltage and damage equipment sensitive to reduced voltage
• Low P.F. requires equipment to be constructed heavier to absorb internal energy requirements
• Low P.F. will result in a more expensive system with equipment able to absorb internal loads and larger load requirements
• Utilities will charge a higher cost to industrial and commercial clients having a low P.F.

3 ). Shunt Capacitor at load

Series capacitor for lagging power factor systems

Series reactor and

shunt coil for leading power factor systems

4. lower system costs, increase reliability and increase the system’s
life cycle.