The primary purpose of this Guide is to present and discuss the applicability and limitations of the various measurement methods now in use, or available, for testing the electrical insulation of power apparatus in the field. The purpose of this Guide is also to consider the special conditions encountered in field testing, and their effect on instruments, methods and procedures for making tests on the electrical insulation of power apparatus.

The following general methods of test are either discussed or referred to in this publication:Low-frequency, low- and high-voltage losscharacteristic measurements. The measurement at power frequencies of power factor, dissipation factor or watts loss and capacitance or charging current; or equivalent quantities which define the electric circuit constants of the test specimen in the voltage range of approximately 80 volts to 50 kilovolts or higher. (2) Alternating-voltage corona measurements. The determination of the presence of corona discharge in the test specimen, usually related to the magnitude of the applied power-frequency voltage. The presence and the...

The primary purpose of this Guide is to present and discuss the applicability and limitations of the various measurement methods now in use, or available, for testing the electrical insulation of power apparatus in the field.Although factory tests assure the initial quality and condition, electric apparatus is subject, during shipment and installation and in operation, to influences which may affect the insulation and shorten its useful life. As a result the practice has grown of testing the insulation in the field from time to time to determine its suitability for service and to detect deterioration which can often be checked or prevented by suitable mainte...