The insulation monitor RN 5897/020 of the VARIMETER IMD family provides best and up to date insulation monitoring of modern IT systems in an optimum and state of the art way fulfilling the relevant standards. The device can be used in the most flexible way for AC, DC and AC/DC systems. Mains areas of applications are non-earthed DC charging stations for electric vehicles with mains voltages up to DC 1000 V, that need an extended temperature range. The connection to the monitored voltage system is done via one of the coupling units. The setting of the parameters and the switching values is done by simple and operator friendly rotational switches on front of the device. The operating status is indicated user friendly via a multicolour LED. With a sealable transparent cover the device is protectet against manipulation.