Harmonic Distortion of Current

Published by Dranetz – BMI Case Studies Office building with personal computers, terminals, copiers, and other electric office equipment supplied by three-phase wye service. Facility engineers at this site experienced repeated problems with the failure of electrical distribution equipment. A distribution transformer overheated and failed, circuit breakers were tripping, and electrical connectors were burning out.Continue reading “Harmonic Distortion of Current”

Impact of Thunderstorms

Published by Dranetz – BMI Case Studies As the first thunderstorms of the season begin to roll through, it is important to safeguard your facility’s equipment against the significant damage that can be caused by the high frequency transient energy of lightning strikes. The first step is to make sure that you power monitor isContinue reading “Impact of Thunderstorms”

Service Area Flicker

Published by Dranetz – BMI Case Studies An entire service area of a Midwest facility. The utility was receiving complaints of annoying light flicker from an entire neighborhood. When the utility connected a power monitor to the 240V distribution bus the problem was quantified. The RMS Voltage event summary, Figure 1, indicates the bus voltageContinue reading “Service Area Flicker”

Major Health Care Center

Published by Dranetz – BMI Case Studies Severe power quality problems damaged X-ray equipment, costing $100,000 in one instance. The source of the problem was the switch over from utility to generator power, during regular testing and emergency situations. Figure 1(below) identified the cause of the problem, an out-of-phase transfer, captured by On Power withContinue reading “Major Health Care Center”

Stalled Motors

Published by Dranetz – BMI Case Studies In this case study, we look at an industrial customer with two 1250hp motors on a 4kV circuit, whose motors would not start. To determine the problem, we installed a Dranetz – BMI PP4300 at the motor input. The power monitoring instrument quickly identified the motor itself asContinue reading “Stalled Motors”

Light Flicker In An Office Complex

Published by 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 fromContinue reading “Light Flicker In An Office Complex”

Voltage Transients Causing Diode Failures

Published by Dranetz – BMI Case Studies A plastic extrusion manufacturer in the mid-West had a 480V delta feeding a plastic extrusion machine. The ASD-driven synchronous motor in the extruder had a half-wave bridge rectifier circuit to provide excitation voltage to the pole coils. Diodes on the half-wave bridge exciter circuit were blowing out, andContinue reading “Voltage Transients Causing Diode Failures”

Harmonics Generated from the Source

Published by Dranetz – BMI Case Studies The subject company manufactures meat products such as sausage, salami, and bologna. Most of their load consists of HVAC and refrigeration as they have about 6000 sq. ft. of cold room storage. They also have machinery such as grinders, slicers, and presses. The facility is served by aContinue reading “Harmonics Generated from the Source”