| creepage distance of an insulator divided by the r.m.s. value of the highest operating voltage across the insulator.
NOTE 1 – This definition differs from that of specific creepage distance where the line-to-line value of the highest voltage for the equipment is used (for AC systems usually Um/√3). For line-to-earth insulation, this definition will result in a value that is √3 times that given by the definition of specific creepage distance in IEC 60815 (1986).
NOTE 2 – For ‘Um’ see IEV 604-03-01.
NOTE 3 – It is generally expressed in mm/kV