1.1 This specification covers electrical insulation monitoring devices intended as permanently installed units for use in the detection of ohmic insulation faults to ground in active AC ungrounded electrical systems.

1.2 Limitations—This specification does not cover devices which are not intended for operation for: DC ungrounded systems or AC ungrounded systems with DC components unless AC to DC conversion is isolated from the monitored system with transformers.

1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are included for information only and are not considered standard.

1.4 The following precautionary caveat pertains only to the test methods portion, Section 9, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.