BENDER IRDH265 Insulation Monitoring and Debugging

BENDER IRDH265 Insulation Monitoring and Debugging

In industrial IT systems, insulation monitoring is a critical link in ensuring power supply continuity and personal safety. Bender IRDH265 and IRDH365 ISOMETER series insulation monitoring instruments are designed specifically for ungrounded systems and can monitor IT AC systems, IT AC systems with DC circuits, and IT DC systems. Compared with traditional insulation monitoring solutions, this series has the ability to automatically adapt to system leakage capacitance, AMP adaptive measurement pulse, dual response value alarm, RS-485 communication, and coupling expansion, and is suitable for frequency converters, rectifiers UPS、 Complex load scenarios such as DC drive. This article will provide a practical guide for on-site engineers in terms of functional principles, wiring installation, parameter settings, troubleshooting, and maintenance selection.

Product positioning and applicable scenarios

IRDH265 and IRDH365 are used to monitor the insulation resistance of IT systems. IRDH265 adopts DIN rail to install plastic shell, suitable for installation inside switchgear; IRDH365 adopts a 144 × 72mm embedded panel installation, suitable for control screen installation. Both support 3AC, 3 (N) AC, AC/DC, and DC systems, with voltage ranges covering 3AC 0... 793V, DC 0... 650V, and frequency ranges of 50... 400Hz. When the system voltage is higher, it can be extended to AC 7200V or DC 1760V through AGH series coupling devices.

This device is particularly suitable for situations where there is a DC component or DC fault current, such as six pulse rectifiers, frequency converters, battery chargers, uninterruptible power supplies, and DC speed control devices. In these systems, traditional AC type insulation monitoring may not be able to respond correctly to smooth DC insulation faults, while IRDH265/365 can reliably cover AC, DC, and mixed faults through AMP measurement principles and optional measurement modes.

Core functions and measurement principles

The basic measurement principle of IRDH265/365 is AMP adaptive measurement pulse. The device superimposes positive and negative equal amplitude measurement pulses between the system and ground, and the pulse period depends on the system's leakage capacitance and insulation resistance. When an insulation fault occurs, the measurement circuit closes, the electronic evaluation circuit calculates the insulation resistance, and displays it on the LCD. The leakage capacitance of the system does not affect the measurement accuracy, while the response time is related to the leakage capacitance, insulation resistance, and interference level.

The device provides two adjustable response values, RALARM1 and RALARM2, with a range of 10... 990k Ω and a hysteresis of approximately 25%. When the measured value is lower than the response value, the corresponding alarm relay will activate and the alarm LED will light up. The response time is about 8 seconds at CE=1 μ F, please refer to the characteristic curve for details. The device can also distinguish between AC insulation faults and DC insulation faults, and indicate whether the fault is located at L+or L -.

The self check function is applicable to versions -3- and -4-. When the insulation resistance exceeds 20 times the maximum response value, the equipment automatically performs a self check every 24 hours, provided that the alarm relay has been set to a system fault alarm. The connection monitoring function continuously monitors the connection between the device and the IT system and PE. If the connection is disconnected or has high resistance, it displays "ALARM E-KE" or "ALARM L1-L3". If the insulation resistance of the new system is too high, it may trigger a connection monitoring alarm. At this time, the connection monitoring can be turned off in Setup 2.

Wiring and installation points

During installation, the E and KE terminals must be connected to the protective conductor PE through separate wires. If the equipment is connected to the operating system through L1, L2, L3, L/+, L/- or external coupling devices, the connection from E and KE to PE must not be disconnected or opened. Only one active ISOMETER can be connected to each interconnected IT system, otherwise measurements will interfere with each other.

System connection varies depending on the system type: 3AC system is connected to L1, L2, L3; 3 (N) AC system connected to L1, L2, L3, and N; AC system connected to L/+and L/-; The DC system is connected to L+and L -. The power supply voltage is connected to A1/A2, and it is recommended to install a 6A fuse. According to IEC 60364-4-473, if short-circuit and ground fault protection wiring is used for measurement connections, protective devices may not be added.

The external k Ω measuring instrument is connected to M+/M -, which is not galvanic isolated from the system. If it is connected to the process control system, an isolation converter such as RK170 needs to be used. External testing and reset buttons are connected to T/R terminals. When the LT terminal is bridged, the fault indication will be stored; When disconnected, the fault indication is not stored. The testing and reset button terminals of multiple insulation monitoring devices shall not be connected in parallel for group testing.