Technical papers are published as they come to hand from our industry experts and principal engineers.
Authored by Carlos Gamez, Principal Consultant
In order to develop a successful On Condition Asset Maintenance system, a few key considerations must be kept in mind.
No two organisations are exactly like each other as they have their own context, physical location and cultural environment. Nevertheless, there are common challenges, experiences to be learned and pitfalls to be avoided that can be identified beforehand, read more… On-Condition Maintenance
Authored by Greg Stone, Iris Power
An instrument provider has been circulating an advertisement alleging ‘no need for a different instrument for each application’ to promote its products for on-line Partial Discharge monitoring with any type of PD sensors (including capacitive couplers, RTDs, Stator Slot Couplers, etc.) and any method of separation (including time-of-flight, pulse shape, etc.). According to the data available for its PD monitoring portable instrument, ‘the frequency band is 0.5 to 10 MHz’…. One Instrument for All Applications
Progress in on-line measurement of PD in motors fed by voltage source PWM drives
Authored by G.C. Stone, I. Culbert, S.R. Campbell
Abstract— On-line partial discharge (PD) measurement is now widely applied to motors rated 6 kV and above that are fed from the 50/60 Hz power system. However, during the past several years, many motors are being powered from inverters which facilitate variable speed motors to improve process efficiencies. One of the drives now being used is of the voltage source, pulse width modulation (VS-PWM) type. Such drives generate high voltage impulses in the kV range with risetimes in the sub-microsecond range. These high voltage spikes are a form of severe electrical interference which can make the detection of PD (with magnitudes 1000 x smaller) difficult due to the overlapping frequency content in PD and the spikes. Thus PD detection on VS-PWM has been a challenge in spite of the serious insulation aging that such drives may cause. This paper outlines the challenges in measuring the stator winding PD in motors fed by VS-PWM drives and describes a newly-developed measurement system. Initial results from a 45 MW compressor motor are presented. read more>Progress in on-line measurement of PD in motors fed by voltage source PWM drives