IRDH575B1-427 Bender

ISOMETER® IRDH575 Insulation monitoring device for unearthed AC, DC and AC/DC systems (IT systems)with control and display function for EDS insulation fault location systemsProduct descriptionThe ISOMETER® of the IRDH575 series monitors the insulation resistance of unearthedpower supplies (IT systems). It is suitable for universal use in 3(N)AC, AC/DC and DC systems. AC systems may include extensive DC-supplied loads, such as converters or thyristor-controlled DC drives. The IRDH575 in combination with EDS4… series insulation faultlocators and the appropriate measuring current transformers is designed to set up the respective equipment for insulation fault location.Function insulation monitoringWhen the insulation resistance between the system conductors and earth falls below theset response value, the alarm relays switch and the alarm LEDs light up. Two separatelyadjustable alarm relays (N/C or N/O operation) allow a distinction to be made between“prewarning” and “alarm”. The measured value is indicated on the LC display or an externally connectable measuring instrument. In this way any changes, for example when circuits are connected to the system, can be recognised easily. The fault message can bestored. The fault memory can be reset by pressing the internal or external reset button.By pressing the test button, the function of the device as well as the connections to system and earth can be tested. Pressing the Info key provides additional information, suchas the existing system leakage capacitance or device settings.Function insulation fault locationInsulation fault location is carried out with EDS4… series insulation fault locators and therespective measuring current transformers. When the IRDH575 detects an insulationfault, the insulation fault location process is started automatically or manually. TheIRDH575 generates a locating current the amplitude of which is dependent on the existing system voltage and the insulation fault. When low-resistance insulation faults occur,the locating current is limited by the IRDH575. This limit value can be set via an appropriate menu. The locating current pulse flows from the IRDH575 via the live parts, taking theshortest path to the location of the insulation fault. From there, it flows via the insulationfault and the PE back to the IRDH575. This locating current pulse is then detected by themeasuring current transformers located in the insulation fault path, and is evaluated bythe EDS… insulation fault locators. When the locating current in the measuring currenttransformer exceeds the response value, the associated alarm LED at the EDS47… lightsup indicating the faulty subcircuit. This information is also indicated on the LC display ofthe IRDH575. By assigning the measuring current transformers to the respective circuit,the point of fault can easily be detected.Additional functions99 alarm messages with date and time can be stored in the data memory of the IRDH575.The device also includes Isometer disconnecting relays when several ISOMETER®s are operated in (coupled) IT systems. An integrated RS-485 interface (BMS protocol) allows information exchange with other Bender devices.Via the 0/4-20mA interface details about the insulation resistance can be transferred tohigher-level control systems.The function of the IRDH575 is continuously monitored. When a system fault occurs, theassociated alarm LED lights up and the respective alarm relay switches.System designBasically, an EDS system consists of an IRDH575 and one or several EDS4… insulationfault locators with the associated measuring current transformers. Information exchangebetween the EDS4… and the IRDH575 takes place via a time and cost-saving RS-485 interface. Such a system may include up to 90 EDS4… so that a total of 1080 circuits can bemonitored.