Power Transformer Temperature Indicator Testing

Summary

This 34-minute DVD describes power transformer temperature indicators, their components, how they work, and how they are tested. Temperature indicators are used on a power transformer to monitor and control the transformer's temperature. Temperature control is important because excessive heat can reduce the useful life of a transformer's oil and speed up the deterioration of the transformer's winding insulation. If heat is not controlled, it can significantly shorten the life expectancy of a power transformer.

Training Sessions

Temperature Indicators – 9 minutes
States the functions of an oil temperature indicator in a power transformer. Identifies the components of an oil temperature indicator and explain how an oil temperature indicator works. States the functions of a winding temperature indicator in a power transformer. Identifies the components of a winding temperature indicator and explains how a winding temperature indicator works.

Temperature Indicator Testing – 9 minutes
Identifies the main components of test equipment typically used to check the calibration of oil temperature indicators and winding temperature indicators. Describes how to check the calibration of oil temperature indicators and winding temperature indicators. Describes how to check snap-action switch turn-on and turn-off temperatures.

Heater Circuit Testing, Part 1 – 9 minutes
Describes how to test the heater circuit for a winding temperature indicator. Calculates the amount of test current that should be applied to a heater circuit on a given power transformer. Evaluates the results of a heater circuit test.

Heater Circuit Testing, Part 2 – 6 minutes
Explains why it is necessary to calculate the heating element current when a heater circuit that contains a calibrating resistor is tested. Calculates the actual current that reaches the heating element in a heater circuit that contains a calibrating resistor. Evaluates the results of a heater circuit test when the heater circuit contains a calibrating resistor. Briefly describes the test setup for testing a heater circuit containing a current-balancing autotransformer.

Support Materials Available

Student workbook, instructor guide.