- Iso D4 insulation monitor for continuous control of insulation towards earth
- Suitable for IT systems with 24...400 VAC
- Selectable alarm threshold from 20...200 kΩ
- 6-position threshold setting by rotary switch
- Alarm indication via red LED and relay output
- Automatic reset and manual test for function checking
- 1 SPDT changeover contact with 5 A / 250 VAC contact rating
- 4-DIN-module housing for DIN rail, screw or optional flush mounting
 Datasheet
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- Iso D4 insulation monitor for continuous control of insulation towards earth
- Suitable for IT systems with 24...400 VAC
- Selectable alarm threshold from 20...200 kΩ
- 6-position threshold setting by rotary switch
- Alarm indication via red LED and relay output
- Automatic reset and manual test for function checking
- 1 SPDT changeover contact with 5 A / 250 VAC contact rating
- 4-DIN-module housing for DIN rail or screw mounting
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Datasheet
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- Insulation monitor for medical locations and hospital use
- Continuous monitoring of insulation towards earth in medical IT systems
- Suitable for operation with Iso TV insulation transformer
- Monitoring of insulation values, transformer temperature, current, voltage, frequency and power
- Programmable alarm and pre-alarm thresholds for insulation, temperature and power
- LCD display with 7 measurement pages and LED alarm indications
- RS485 communication, JBUS / MODBUS compatible
- 4-DIN-module housing for 35 mm DIN rail mounting with IP54 front frame
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Datasheet
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- Iso D4-Zs insulation monitor for medical locations and hospital use
- Continuous monitoring of insulation towards earth in connection with Iso TV insulation transformer
- Monitoring of insulation resistance or impedance, transformer temperature, current, voltage, frequency and power
- Programmable alarm and pre-alarm thresholds for insulation, transformer temperature and power
- LCD display with 7 measurement pages and LED alarm indications
- RS485 communication, JBUS / MODBUS compatible
- Outputs for insulation alarm, temperature / power alarm and Iso QZ remote repeater panel
- 4-DIN-module housing for 35 mm DIN rail mounting with IP54 front frame
| Datasheet |
- Single-phase safety isolating transformer for insulation monitoring systems
- Used with Iso D4-Zs insulation monitor NT689
- Primary voltage 230 V, secondary voltage 24 V
- Rated output 1 kVA
- Rated frequency 50...60 Hz
- Dry transformer with insulation class F
- Rated insulation level 2.5 kV R.M.S. for 1 minute
- Screw terminals, IP00 enclosure and IP20 terminals
| Datasheet |
Insulation Monitoring Relays
An insulation monitoring relay monitors the insulation integrity of a power supply or installation — especially in IT-networks, unearthed systems, or isolated supply circuits. It continuously checks insulation resistance or leakage currents relative to earth or reference ground, and detects insulation faults early. If a predefined threshold is crossed, the relay triggers a signal or protective action (alarm, shutdown, etc.). These modules are typically DIN-rail mountable for straightforward integration into existing switchgear or distribution systems.
Questions & Answers on Insulation Monitoring Relays
What is an insulation monitoring relay?
A device that monitors the insulation resistance or leakage current of a supply circuit and triggers an alert or output when insulation degrades or a fault occurs.
Where are such relays used?
In IT-power networks, critical systems, medical facilities, industrial equipment — wherever insulation integrity and early fault detection are essential.
How does the monitoring work?
The relay measures insulation resistance or leakage current relative to earth/reference. If resistance drops below or leakage exceeds a set threshold, the relay signals a fault.
What kind of output does it provide?
Typically a relay contact or switch output that can be connected to control, alarm, or shutdown circuits.
Is galvanic isolation part of the design?
Yes — input (power circuit) and output (signal) are galvanically separated to avoid interference, ground loops or unintended current paths, ensuring safety and reliability.
How is the device installed?
It is mounted on a DIN rail and wired to the power supply conductors; the output is connected to alarm or monitoring systems.
In which applications are insulation monitoring relays particularly useful?
In isolated or unearthed supply systems (IT-networks), safety-critical installations, industrial plants, building services, medical or lab installations — wherever insulation faults must be detected early.
What are the main benefits?
Early detection of insulation faults, enhanced safety, protection against earth faults or leak currents, easy retrofitting, and reliable signaling for fault handling.
What do you need to watch out for?
Correct wiring and adherence to specifications are essential. Regular testing and maintenance is recommended to ensure continued effectiveness; incorrect installation may render the protection ineffective.