Technical aspects affecting the use of insulation monitoring devices A-ISOMETER® Required insulation values and recommended response values of insulation monitoring devices (IMDs) RequiredInsulationResistance Recommendedresponse valueof the IMD NominalVoltage Standard Application
IEC 60364-5-53 Annex HSelection and erection of electrical equipment – Isolation, switching and control230 Vpre-warning100 Ω/V=23 kΩwarning50 Ω/V=11.5 kΩ34.5 kΩ17.25 kΩIEC 60364-7-710Medical locations230 V50 kΩ75 kΩUL 2231-2Supply Circuits for electric vehicles100 Ω/V at nominal voltages 5.6 Expansion of the nominal voltage range AGH coupling devices can be used to expand the nominal range of an insulation monitoring device. These modules are connected between the insulation monitoring device and the system to be monitored. 5.5.1 Response values for control circuits If, in accordance with IEC 60947/DIN VDE 0660 and DIN VDE 0435 U
n is taken as the minimum withstand voltage (0.1…0.15) for an actuating element integrated in the control, disregarding coil im- pedance, a resistor ZH connected in series which is able to pre-vent tripping at 5% overvoltage can be dimensioned as folows:ZH ≈ (10.5…7) U
n2 PHPH = Rated apparent withstand power of the actuating element.This formula can be used to calculate the following recommen-ded response values for the insulation monitoring device in con- trol circuits (values in Ω): 1 VA 5 VA 10 VA 30 VA 50 VA 24 V 6048 Ω 1210 Ω 605 Ω 202 Ω 121 Ω 48 V 24192 Ω 4838 Ω 2419 Ω 806 Ω 484 Ω 60 V 37800 Ω 7560 Ω 3780 Ω 1260 Ω 756 Ω 110 V 127050 Ω 25410 Ω 12705 Ω 4235 Ω 2541 Ω 220 V 508200 Ω 101640 Ω 50820 Ω 16940 Ω 10164 Ω 230 V 555450 Ω 111090 Ω 55545 Ω 18515 Ω 11109 Ω
Figure 5.7 Expanding the nominal voltage range of an insulation monitoring device Figure 5.6 Insulation monitoring response values for a control circuit Annex 1.9.1 Main catalogue part 1 – 08.2007/Insulation monitoring 169