On-site measurement of load and no-load losses of GSU transformer
Present development and production of power transformers with lower losses in addition to replacement of outdated transformers assume regular measurement of losses in both load and no-load regime. These measurements are very demanding especially in the case of on-situ measurements. The complexity of the measurements grows with the size of transformer. This paper presents one typical test of losses measuring in load and no-load regime of power transformer with nominal power of 40 MVA in HPP Perucica.
No-load loss measurements of power transformers under distorted supply voltage waveform conditions
The problem of correcting the results of no-load loss measurements of power transformers for the effect of distorted supply voltage waveform on the magnetic flux in the core and hence on both the hysteresis and eddy current loss components of core losses is presented. The instrumentation requirements for no-load loss measurements to ensure proper application of the correction formula are described.
A TDM wattmeter with a 0.5-MHz carrier frequency
The operating principle and design of a TDM (time-division multiplexer) wattmeter with 0.5-MHz carrier frequency are described. At power frequency the meter was compared with the National Research Council's current-comparator power bridge. The nonlinearity error of the meter was smaller than 100 ppm of full scale over the wide range of inputs and the whole range of power factor. Preliminary results have shown that the frequency dependent errors are below 100 ppm up to 2 kHz in the whole range of power factor. This accuracy is comparable with the accuracy of the standard thermal wattmeters. However, the meter itself is more compact, is relatively simple, and has a faster response time. The design described demonstrates that relatively simple corrections permit a considerable increase in the TDM wattmeter carrier frequency, thus decreasing its systematic frequency errors. >