Bender ISOMETER IRDH375, Manual

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Connection
41 IRDH375_D00124_05_M_XXEN/01.2020
The maximum DC voltage is the voltage permitted to occur in the AC part of
an IT system to PE when the IRDH375 is coupled with AGH204S-4 in this part
of the system. This voltage is dependent on the level of the nominal voltage,
the type of rectification 6 pulse, 12 pulse,…), the type of converter intermedi-
ate circuit (current… or voltage…), and the converter technology. In case of
converters, the maximum DC voltage in the intermediate circuit usually corre-
sponds to the phase-to-phase voltage of the supplying AC system multiplied
by 1.414.
In case of current-controlled intermediate circuits of frequency converters,
higher DC voltages are to be expected.
The given voltage values for AC/DC systems take into account values found by
previous experience (factor 1.414 between DC voltage and AC voltage).
The maximum DC voltage in case of insulation faults in the DC part of the IT
system, for example converter intermediate circuit, is DC 1840 V. From this,
the maximum nominal AC voltage is calculated:
U
max
= DC 1,840 V/1.414 = AC 1,300 V