Insulation Tests of Electrical Machinery Before and After Being Placed in Service

The A. I. E. E. Standards have provided high-potential test values as a means of establishing a standard basis of design and construction of insulation. Many purchasers test equipment after installation before placing it in service to be sure that the connections and equipment are in a safe condition for service. It is recommended that a Standard Test Voltage be established that may be used under these conditions. It also seems to be advisable that suitable rules should be set up governing test voltages that should be used in a maintenance program. Periodic observations of the insulation resistance are suggested as substitute or supplemental tests. If there is a general desire that rules of this sort should be made, it is proper that the Institute should enter this new field of standardization.