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Present methods of measuring transformer temperature rise require instrumentation with a high degree of accuracy, expensive temperature-control chambers, and relatively skilled operators. A new approach and method is described which provides equal or better accuracy while employing less accurate instruments, a lesser degree of operator skill, and without resorting to temperature-controlled test chambers. This paper describes a bridge test circuit which utilizes a calibrated temperature-rise "standard" which acts as a reference in evaluating a test unit. The bridge circuit provides a measure of compensation for varying electrical and ambient conditions. Data and curves are presented which indicate that the constant-temperature chamber could be dispensed with, except for the purpose of calibrating reference "standards."