We are issuing this technical bulletin regarding the use of EURV-MRU 240V Mains Rated Relay Unit (and derivative) mains switching module. The EURV-MRU relay unit upgrades a standard output module to a unit capable of switching mains voltages and higher currents.
What may happen?
The wired, loop powered variant of the product only may be impacted by the following issue.
It may occur only if a specific and defined set of conditions is met:
Under normal operation, the panel actions the output module which initiates the EURV-MRU module (when connected) in order to switch AC mains supply (usually this follows an event/alarm condition from CIE, which is fully logged/recorded in the systems event log).
In the event of a short circuit on the loop wiring, the loop isolator either side of the fault will open as a result. The panel will put in place the proper reaction to the short circuit condition: may vary by control panel type but mostly powering from both ends of the loop. Devices either side of the affected loop isolators (each side of the short circuit) should continue to communicate with the panel.
The output module has a bi-stable signal relay, so it remains in its last active condition even if the module has lost power.
An issue with the EURV-MRU has identified a defect which may impair the reconnection capability of the loop isolators.
This means that a larger part of the loop may remain isolated between the short circuit and the resulting open isolators even when power is applied to both ends of the loop. The effects are greater if the short circuit occurs close to panel loop output (loop-out).
The panel will indicate (device missing[s]) fault for the affected devices, however the displaying of any alarm condition will always take priority on the display.
What is not impacted?
The wireless variants are not impacted at all (the EURV-MRU unit can easily be upgraded to a wireless variant by adding the end of line module and connecting to a wireless output module).
What should you do?
Should you find any of your systems at risk of the above situation, please consider one of the two possible alternative solutions below:
– option A, with isolator modules spur
– or option B, if you have already on site an external power supply (24V PSU).
We will provide you with a pre-cabled: inside it you will find 3 isolator modules that will spur the EURV-MRU form the main loop.
Such configuration ensures the EURV-MRU operation does not affect the loop in any conditions and ensures that the EURV-MRU operation is maintained regardless the position of the potential short.
You can add an external power supply (24V PSU) to decouple the mains relay from the loop, using the end-of-line module paired with EURV-MRU.
The EURV-MRU can be considered a type 2 component from the EN 54 perspective, therefore use of a non EN54-4 approved power supply is also acceptable.
For any sites that may be affected with this issue, we ask you to contact us immediately to arrange replacement of the EURV-MRU 240V Mains Rated Relay Unit.