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.

Alarm relays K1/K2 each have a switching contact, which can be set to normally open or normally closed. Terminals 11-12-14 correspond to alarm 1, and 21-22-24 correspond to alarm 2. In the absence of an alarm, the normally open operation is "12-11-14" closed, and the normally closed operation is "12-11-14" closed.

Parameter Setting and Debugging

Before debugging, it should be confirmed that the power supply voltage is consistent with the nameplate and the system voltage is within the allowable range. The basic factory settings of the equipment vary depending on the version, for example, -3 version alarm 1/alarm 2 is 40/10k Ω, -4 version is 180/40k Ω, -7 version is 600/300k Ω, -8 version is 1M Ω/500k Ω. The maximum system leakage capacitance is usually set to 150 μ F or 500 μ F at the factory, and -7- and -8- versions are 2 μ F. It is necessary to verify whether the basic settings meet the system requirements.

Setup 1 includes basic settings: password query, response values ALARM1/ALARM2, alarm relay operation principle, and branching to Setup 2. The response value can be modified by pressing the up and down keys, and saved by pressing the enter key. The operating principle of the alarm relay is to select normally open or normally closed through "12-11-14" and "12-11-14". Setup 2 is an extended setup and is recommended to be operated by personnel familiar with the equipment and system.

Alarm functions can be set in Setup 2: AC OR DC, ONLY AC, ONLY DC, ONLY DC+, ONLY DC -, SYST. There are limitations to different combinations, and combinations without alarm activation cannot occur. The coupling device settings need to select AK... AK80 or AK... AK160 according to the AK terminal connection, corresponding to different voltage ranges. It is recommended to keep the connection monitoring open. The flashing function can cause the alarm relay and LED to flash at 1Hz. Relay testing can turn off the relay action during functional testing. Time delay is applicable to versions -3- and -4-, and asymmetric measurement principle or superimposed DC measurement voltage needs to be selected first. CE MAX matching system leakage capacitor, -4 version can choose 150 μ F or 500 μ F, and when choosing 500 μ F, the basic measurement time increases to 15 seconds. It can also activate passwords, enter new passwords, reset basic settings, view software versions and status words.

Setup 3 is used to select measurement principles: AMP, DC, UG/AMP, AMP/UG. AMP is the basic setting. DC voltage measurement is suitable for pure AC systems. UG/AMP passive asymmetric measurement is suitable for DC systems. By setting Ian, DC fast response can be achieved. The alarm is output through ALARM2, and then AMP measurement is automatically started. The insulation resistance alarm is output through ALARM1. AMP/UG is the combination of AMP and asymmetric measurement, and the fault indication is output through ALARM2 and ALARM1 respectively. The fast DC response current Ian can be set between 0.1... 5mA.

Coupling devices and extensions

When the system voltage exceeds the direct measurement range of the equipment, coupling devices need to be used. AGH204S-4 is used for AC 0... 1650V, AGH520S is used for AC 0... 7200V, and AGH150W-4 is used for DC 0... 1760V. When the AK terminal is connected to AK80, the working range of IRDH265/365 is extended to 3AC 0... 1650V; When connecting AK160, it can be extended to 3AC 0... 1300V, allowing the DC part to reach DC 1840V. Extend to AC 0... 7200V when connecting AGH520S terminal 5. Please note that only current converters with an output voltage not exceeding 1000V are allowed to be connected.

For AC systems with rectifiers, the maximum DC voltage depends on the rated voltage, rectification type, inverter intermediate circuit type, and inverter technology. Voltage type intermediate circuits usually correspond to the phase to phase voltage multiplied by √ 2. Current type intermediate circuits may experience higher DC voltages. Calculation example: If the maximum voltage of the DC part is DC 1840V, then the maximum rated AC voltage is 1300V.

Common troubleshooting

1. The device is not powered on and shows no response

Check if the A1/A2 power supply voltage is consistent with the nameplate and if the power supply fuse is blown. If the power supply is normal but there is still no display, it may be an internal power failure and needs to be replaced.

2. Normal insulation but frequent alarms

Check if the response value is set too low and if the CE MAX matches the actual leakage capacitance. If the system leakage capacitance is large, choose 500 μ F and extend the response time. Check if the measurement principle is suitable for the system. For pure AC systems, DC measurement voltage can be selected, and for DC systems, UG/AMP can be selected. Confirm if the connection monitoring is falsely reporting due to high insulation resistance, which can be turned off in Setup 2.

3. Display ALARM E-KE or ALARM L1-L3

Indicates that the connection between the device and the system or PE is disconnected or has high resistance. Immediately check the wires from E, KE to PE, as well as the L1/L2/L3 or L+/L - connections. If the insulation resistance of the new system exceeds 20 times the maximum response value, this alarm may also be triggered and the connection monitoring can be turned off.

4. Display TEST ALARM

System malfunction. Cut off the power supply briefly before powering it on. If it still displays after the response time, it may indicate a device malfunction and the manufacturer needs to be contacted.

5. Unable to reset after alarm

Short press the TEST/RESET button (<1s) to reset. If the LT terminal is bridged, the fault indication is stored and needs to be reset. If the fault persists, the device will sound an alarm again. Check the wiring of the external reset button.

6. Communication abnormality

RS-485 interface connected to A/B terminals, maximum cable length 1200m, protocol 9600 Baud, 1 start bit, 1 stop bit, 8 data bits. Check the terminal resistance, shielding, and polarity. Data is sent continuously and cannot be interrupted by other bus members.

7. Slow response to insulation faults in DC systems

Select UG/AMP or AMP/UG measurement principles and set Ian to the appropriate value. Pay attention to the direct connection of the DC circuit to the AC system, and the load current of the rectifier needs to be greater than 5... 10mA to be monitored correctly.

8. Fluctuations or inaccuracies in measurement values

Check if the system leakage capacitance exceeds the set CE MAX and adjust it if necessary. Confirm that the measurement principle matches the system type. Check for strong interference sources and ensure that wiring is kept away from power cables.

Maintenance and selection suggestions

Regular maintenance includes: functional testing every 6 months, using real ground faults or testing buttons; Check terminal fastening and wire insulation; Clean the surface of the equipment to avoid dust and moisture; Confirm the storage temperature of -40...+75 ° C and the operating temperature of -25...+70 ° C. Before resuming operation after a long-term shutdown, the basic settings and measurement principles should be checked.

When selecting, choose the model based on system voltage, frequency, leakage capacitance, and load type. The standard IRDH265-4 is powered by AC 230V and is panel mounted. If higher voltage is required, AGH coupling equipment can be selected. If external display is required, the 7204 or 9604 series k Ω measuring instruments can be selected. If a process control interface is required, an RK170 measurement converter can be equipped. For systems with a risk of DC faults, priority should be given to version -4, which supports a wider response range and CE MAX settings.