Application of PC-based measurement techniques to ASD performance evaluation

Two basic techniques that can be used in a laboratory environment to evaluate the performance of an adjustable speed drive (ASD) are discussed: sampling and direct. The sampling technology relies on computer technology, since it requires reliable, high-performance A/D converters along with sophisticated data interpretation techniques. While several sources of error are possible in the various isolators and current probes/amplifiers required, the sampling technique offers the inherent advantage of highly flexible offline data interpretation possibilities. Sampling measurement techniques can be made nonintrusive so that they do not disturb ongoing associated processes. The direct measurement techniques require sophisticated instrumentation that may not always be convenient or even possible to utilize in a field test. The associated measurement errors are often negligible; however, the inherent bandwidth limitation of the instruments are often a concern.