2/201 8 | MONITOR | 15 The isoCHA425 is designed for a nominal voltage range between DC 50 V and 500 V. Single-pole insu- lation faults R F are detected and reported within 1 second, two-pole insulation faults R F (insulation fault R F simultaneously between DC+/earth and DC-/earth) within 10 seconds. The maximum permissible system leakage capacitance C e is 2 µF. The device measures insulation resistance RF and system leakage capacitance C e to earth. It also meas- ures the system voltage U n between L+ and L- and the residual voltages U L+e (between U L+ and earth), and U L-e (between U L- and earth). The isoCha425 detects the faulty system conductor DC+/DC-, i.e. the distribution of the insulation resist- ance between the DC+ and DC- system conductors, from the minimum value of the nominal system voltage, and indicates this with a plus or minus sign for the insulation resistance measurement. Partial resistances can be calculated from the total insula- tion resistance R F and the faulty conductor (R %). It is also possible to assign a detected fault or faulty conductor to an alarm relay via a menu. If the values R F or Un continuously exceed the response values activated in the "AL" menu for the period ton, a message is output via the LEDs and relays K1 and K2 according to the alarm assignment set in the "out" menu. The operating principle of the relay (n.o./n.c.) and the fault memory can also be set there. Device functionality can be checked using the test button "T". Parameters are assigned to the device via the LC display and the control buttons on the front panel; this function can be password protected. The device can be parameterised via the BMS bus, e.g. via a BMS Ethernet gateway (COM465IP) or via Modbus RTU. Dipl.-Ing. Frank Mehling BU eMobility Solutions INFO More information: https://www.bender.de/en/products/insulation-monitoring/isometer_isocha425 "A DC charging station is the method of choice for the fast charging of electric vehicles."