Auxililary relay for trip circuits

You probably won't go too far adrift if you based it on Argus relays (Siemens) - the Argus C is a pretty useful bit of kit that can cover pretty well any and all protective functions, and is a proven reliable unit for "fail to trip" send upstream and other of the slightly more specialist functions including say H7 supervision


I've assumed you have room to fit them - and that the existing CT's can be re used or replaced - but if you can't get a GE MVAA to fit, then there is probably little chance of getting any of the other reputable brands to physically fit either - unless you can add top boxes to the LV compartment cubicles (don't know if you have top or bottom entry switchboards - or both).


If you can sensibly define the protection arrangements (ANSI or old school) then a chat with a good reputable independent switchgear manufacturer would be worth while to see whay could be achieved with the existing gear


Regards


OMS

Thanks OMS. Aren't those protection relays or do you mean 7PG11 and similar (which are similar to the MVAA)? The protection functions are already in place, though some are remote, it's just a matter of controlling which ACBs to trip under different fault conditions and keeping different control voltage sources separate.

It might be easier to retrofit additional tripping mechanisms to the ACB (e.g. UV as well as shunt)... I was hoping there might be a DIN mounted device with say a single element and two CO outputs, just suficiently reliable for protection. Maybe it doesn't exist though!

....It'd be a lot easier to design from scratch, as then I could use the multiple output relays of the protection devices, but am limited by, for example, the number of existing cores.

Ahhh - apologies, I thought you were looking to replace the protective functions and the control functions with replacement relays.


You are keeping the protective functions (generally)  but need to replace the control functions then ? - but still interface with the protective functions


MVAA or similar may well be OK - but they aren't specifically protection relays, more they are auxiliary elements that can combine with protective relays - personally, I wouldn't want to rely solely on an auxiliary for a protective function unless it's got some duplication or back up, but I think you already have that anyway


What make are the ACB's  - and does that specific manufacturer provide an add on auxiliary relay unit which may well be reliable enough for your purposes (even if you have to effectively refurb the ACB)


Regards


OMS

No worries. For context, the ACBs (Schneider Masterpact NW) are providing OC internally. Remote trips are coming from LV insulation monitioring (1 of 2, though both are equipped), a load shed command (1 of 2 ACBs), HV intertrip (both ACBs) and interlocking with one of the downstream MCCBs. Nothing particularly magic, but the IMD is required for ADS.


I agree I wouldn't rely on the auxiliary for the protection directly but what I need is something to reliably duplicate signals coming from trips they have in common. Alternatively I could trip everything on anything, which is tempting but a little graceless, or rejig the arrangement further.