Help connecting QUA6A PFTU to ACT 28

[imukonyezi]

We have an ACT 28 with an NDDI2 (LS/GS) card for analog trunks and eZ32 for analog extensions. We are deploying a Power Failure Transfer Unit (PFTU) made by Nortel, Model QUA6A to transfer specific analog lines to analog trunks in case of ACT failure. However, the control interfaces of the PFTU require a ground signal from the ACT to be connected to the PFTS terminal on the QUA6A to activate the transfer mode when ACT power fails.

I was expecting the CMDFRMA cable to provide this signal but I cannot see a connection for a power fail ground signal.

Please guide me on how I can receive this ground signal from the ACT in case of power failure.

[vad]

As I understand - when you connect power to ACT - you connect by 3 wire - 0V48, -48V and PSAL (Power Supply Alarm). May be you can use PSAl (but not sure).
Another solution - check you Power Supply System - usually such system has dry contact for alarm indication.

[imukonyezi]

Thank you Vad. Yes the ACT has 3 wires including PSAL. Let me check it out and return with feedback.

[imukonyezi]

Hello Vad, today I managed to test the pftu with the signal from the PSAL. PSAL is connected to - 48VDC source, But now I am having voltage dropping to 4 or 5vdc when I connect the PSAL. I even measure on the terminal block the 48VDC but when I connect PSAL point the voltage drops to 3-4VDC and the CPU can't start as it shows waiting for PSAL... I see this message when I connect via console cable.

But when I disconnect PSAL the voltage on the terminal block restores to 48VDC.

In the drawing there is a connection to an ET board and it seems that's where it gets the voltage from. Attached is the drawing.

Now I am doubly confused. Please help me Vad.

[vad]

I'm think - PFTU unit input - not correct load for PSAL signal (I don't now - what is PFTU unit input - signal input, or just relay).
Your PABX powered wrom some PSU. Your PSU have some alarm outputs?

[imukonyezi]

Thank you Vad.

Please find attached the manual part for the connection point for the PSAL on the terminal block. I was connecting to the PFTS terminal (2T). The PFTU activates transfer mode when PFTS terminal is ground (0V). So it just monitors the pfts signal, I don't know if it sends anything back to the PSAL.

[vad]

I think - PSAL was not good idea. PSAL activated, when ACT have problem with power. But if Power supply not works - PFTU not works too. Or you have another power supply for PFTU?

[imukonyezi]

Hello Vad.
Thank you so much for the support.
Indeed it wasn't a good idea to use PSAL on PFTS.
And indeed the power supply for ACT and PFTU is the same. In the future maybe the design will be modified to separate power supplies.
But now we are opting to use an interposing relay that can switch ground to PFTS based on whether ACT is ON (NO Ground) or OFF (GROUND).

[alex]

PSAL is a bad idea...
Any ACT CPU has alarm pins and trunk line diversion pins.
Trunk Line Diversion siognals RL1 and RL2 - pins B11 and B12 on DIN96.
But you can't use them directly as these contacts are closed in normal conditions and open when PS or CPU fails.
If you have CMDFRMA cable you get them on pin 3 and 16.

[imukonyezi]

Thank you, Alex.
We have CMDFRMA cable and we will test with pin 3 and 16 RL1 and RL2 respectively, with a double pole 48VDC NC/NO interposing relay.