Nidec DFS Series Power Installation Manual

DFS1/DFS2 Power Installation Guide 35Issue Number: 2Safety information Product information Mechanical installation Electrical installation Technical dataTable 4-1 AC supply specification4.4 Operation on IT (ungrounded) suppliesParameter RatingVoltage 380 V to 480 V ±10 % 500 V to 690 V ±10 %No of phases 3Supply frequency 45 to 66 HzSupply type TN-S, TN-C-S, TT, ITOvervoltage category OVC III (according to IEC 60664-1) 11. For installations where the equipment is installed at the origin of the supply, additional over-voltagesuppression (transient voltage surge suppression) must be provided to reduce the overvoltage categoryfrom OVC IV to OVC III.Impulse voltage rating 4 kV for 400 V, 6 kV for 690 V drivesMaximum supply imbalance 2 % negative phase sequence (equivalent to 3 % voltage imbalance betweenphases).Auxiliary transformer tap settingBefore powering up the drive, it is important to check that the auxiliary transformer tappinghas been set correctly. Wrong selection could result in damage to transformer and the rooffans.Operation on IT (ungrounded) suppliesUnusual hazards can occur on IT (ungrounded supplies).A ground (earth) fault in the incoming supply has no effect. The drive will continue to run.However, the phase to phase voltage will appear between two of the supply terminals andground (Earth). On a 690 V supply, this will stress the insulation.A ground (earth) fault in the motor circuit may not cause the drive to trip. If the motoris required to continue to run with a ground fault in its circuit, then an input isolatingtransformer must be provided. If an EMC filter is required, it must be located on theprimary side of the isolating transformer.The following measures must be taken:Additional, independent motor ground fault protection must be provided.EMC filters must not be usedThe internal EMC filter inside the drive module must be disconnected 1 .1. Disconnection of the internal EMC filter on frame size 11E is only possible at the factory. This must bespecified when ordering.WARNINGWARNING