TAC 20 duplex with UPS units

We just installed some UPS units for battery lowering on a TAC20 duplex. The cars recover properly but when car 1 in the group is tested it knocks out the hall calls in the group and car 2 is a dead duck. The group status changes to EmerPower. Is this a problem with TAC20 group software. The EPNP input on car 2 never goes low but the signal is being communicated through the group communication. EPNP inputs are isolated and all parameters seem to be correct.

Anyone got an ideas?

Both cars level down and open the doors. Car 1 goes on emerpower and runs normal and car 2 stays at the bottom landing with the doors open?

Common for when a building runs off a generator. So you want both cars to run on emerpower?

Nope, guess I should explain a little better. Each car should perform battery lowering independently. The building is not on generator power. After they are lowered to the recall floor they would shut down. The problem occurs if only car 1 loses the EPNP input. It locks up car 2 even though the EPNP input on car 2 is still high. Not sure when this would ever occur in a real situation but the inspector wanted to see them both recall independently without affecting the other car.

Understand this topic is old, but if you have not fixed it yet, here we go. The crossconnects will need to be severed, at each car, using an AC relay. Power for the relay will come from the transformer in each car, x1. When the car loses high volt, it will sever the crossconnects, allowing the powered up car to function normally, and vice versa. You can verify this potential fix by pulling the crossconnects (usually two shielded sets) and see how they work.

I am in the process of doing this for a TAC 32, known issue at TKE, they just do not see the scenario as being realistic enough to redo software for it.

Thanks... That is exactly what I did. Do you know if the LON connection from the hall is supposed to go to both cars in parallel? Reason for asking is when group communication is interrupted slave car goes on wild car operation with no connection to the LON network. I would think LON dispatching would switch over to the car in service and not on EPNP.

Chevy you could try leaving the group LON up and see if only severing car information doesnt kick it back. My scenario with the TAC 32 is actually better, and worse, in the fact I have dual risers. I know your EPNP stays active, you are just losing HCIE, just like when the car goes into fire service. Makes me wonder if you only tried to sever the car LON, if the group portion would stay working. Another thought as well, with the TAC 20 there are some spare ports. TAC 20's do look for similiar nomenclature, perhaps you could use a back set of contacts, create a new HCIE off the spare port, and bingo, trick that bum into thinking life is good.

EPW is on a 10 second window switch that changes it from epnp when there is a power outage .. it never seems to work great
When returning back to normal power