ISOM complementary modules
ISOM add-on modules allow the capabilities of an existing insulation control system to be extended by adding…
Complementary ISOM modules are functional extensions for already-installed insulation monitoring devices. These modules allow alarm-reporting relays, additional inputs/outputs or communication interfaces to a centralised supervision system to be added, in line with the IEC 61557-8 standard. They mount on DIN rail in a polyamide housing and preserve the installation's initial investment.
Extension functions available for complementary ISOM modules
Alarm-reporting relays and remote signals
Modules fitted with alarm-reporting relays transmit insulation faults detected by the ISOM controller to remote signalling or control equipment. Our installation experience confirms that this function is particularly useful when an electrical panel is located in a technical room that is not permanently monitored. The relay provides a dry contact compatible with most existing PLCs and mimic panels.
Input and output expansion modules
Input/output expansion modules increase the processing capacity of the base insulation monitoring device without requiring it to be replaced. They allow additional sensors to be integrated or actuators associated with preventive maintenance to be controlled. Our installation feedback shows that this modularity effectively meets the needs of evolving industrial installations where new circuits need monitoring after a panel extension.
Communication interfaces and supervision integration
Communication interfaces convert data from the ISOM controller into protocols compatible with centralised supervision systems. This integration consolidates insulation information within a BMS or a building management system. In the field, we observe that this feature is increasingly requested by design offices for tertiary and hospital installations subject to centralised monitoring of critical electrical parameters.
Normative compatibility and physical integration of ISOM modules
Compliance with the IEC 61557-8 standard
Compatibility with the IEC 61557-8 standard guarantees that complementary modules meet the safety and performance requirements applicable to insulation monitoring devices on IT networks. This compliance ensures interoperability with existing ISOM controllers and the reliability of transmitted measurements. Our standard practice favours strict compliance with this standard for any extension of an initial insulation-monitoring system.
DIN-rail mounting and mechanical characteristics
The polyamide housing of complementary ISOM modules allows direct mounting on DIN rail in the existing electrical panel. This standardised mechanical design makes installation easier as a complement to the insulation controller already in place, with no change to the panel layout. Feedback from installers confirms that this mechanical compatibility significantly reduces on-site intervention time.
Typical applications and installation-evolution contexts
Complementary ISOM modules are mainly aimed at installations where an insulation controller is already deployed but where new functional needs have emerged. The following cases illustrate situations encountered:
- Extending a hospital installation requiring alarm reporting to an existing technical supervision centre
- Adding circuits to be monitored in a factory after modifying the main electrical panel
- Integrating a standalone ISOM system into a BMS during a tertiary-building renovation
- Replacing a faulty signalling relay with a compatible module without changing the controller
We find that these scalable modules preserve the initial investment while adapting the insulation control system to current regulatory and operational requirements.
Frequently asked questions
Can a complementary ISOM module replace a faulty insulation controller?
No, complementary ISOM modules necessarily require a working insulation controller to operate. They extend its capabilities but do not on their own measure the IT network's insulation resistance.
What is the maximum distance between the ISOM controller and its extension modules?
The distance depends on the module type and the communication protocol used. Relay modules generally work locally on the same DIN rail, while some communication interfaces can extend over several hundred metres via a fieldbus.
Does the IEC 61557-8 standard apply to both the controller and the complementary modules?
The IEC 61557-8 standard defines requirements for the whole insulation control system. Complementary modules must be compatible with this standard to guarantee consistent measurement and signalling performance across the installation.
Can several types of module be combined on the same ISOM controller?
Yes, in most configurations it is possible to combine relay modules, input/output extensions and communication interfaces simultaneously on the same ISOM controller, subject to the base system's addressing and power-supply capacity.