Power Quality Practitioner™

"Practitioner is one who brings an art or science to full realization"

2

THE CASE OF MISSING CONTACTS

DRANETZ - BMI CASE STUDIES

​Executive Summary

Defiance Metal Products Company contracted with Electrotek Concepts to perform field measurements of their welding operations, and to make recommendations for remediation of Power Quality problems at the facility.

The customer has been experiencing both major and minor electrical problems. The minor problems include occasional observable flicker in the overhead HID lighting system. The major problems include welder trip during operation and damage to protective MOVs.




LIGHT FLICKER IN AN OFFICE COMPLEX

DRANETZ - BMI CASE STUDIES


The second floor of an end unit of an office-condo complex in the Washington DC area. The office space consisted of a reception and meeting area, two private offices, a kitchen area and a bathroom. The entire area was powered from a single three-phase 208/120V wye feed from a transformer bank located right below and outside the office.

A light flicker problem had been noticeable for a number of years. It was most visible in the bathroom and outside hallway. The source of the flicker was undetermined, though it was suspected to be the HVAC units on the roof, as there was an audible sound in the bathroom that accompanied the flicker.



CAPACITOR BANK FAILURE BY HVDC IN GR MODE

POWER QUALITY MONITOR SYSTEM (PQMS) CASE HISTORY 

Examples:
Date: 2004-05-25, Time: 17:07

  • Imbalance relay protection tripped a 35kV capacitor bank
  • Damage:
    • 16 fuse breakdown
    • 5 sets of capacitors damaged



LOOSE BUS BAR BOLTS CAUSE SAGS

DRANETZ - BMI CASE STUDIES


​An administration building in a government complex in New Jersey had a transformer with a 4KV primary, 120/208V wye, 800A secondary. The buss duct ran up to a second floor panel, which supplied an office area.

Computer misoperations and lights flickering were occurring randomly for nearly two years. Emergency lighting was also flickering.