Control to signal isolation of the relays on the PXI2529

[ehseger]

Is there a specification for the isolation between the coil circuit and the signal contacts for the PXI2529?  I am concerned with AC signals riding on the control circuit injecting into/influencing the signals that are switched by the contacts.  The data sheet does not have the DC isolation value either.

Thanks,

Ed

[TylerC1123]

Hi ehseger,

I took a look at our specifications for this module, as well as the specs for the relay itself (which you can find in the NI Switches Help page) and it looks as though we just don't specify this for this particular module.

That being said can you tell me a bit more about why you are concerned with these AC signals on the control circuit? Such as any behavior you're seeing or your particular application of this module?

Thanks!

[ehseger]

I am asking because I will be switching microvolt AC signals through this board and I want to know the effect (if any) the board will have on these signals.  If there is noise on the relay coil from the power supply, etc, do I have to worry about it coupling into the switched signal.  Small-signal relays seem to have over a kilovolt isolation between the coil and the contacts, what about induced signals between the coil and the contacts?  If I use one of the signal paths for a line-level audio signal, will that signal make it into the microvolt signal path through the ckt board or the relay coil?

Thanks,

Ed

[Frank-L]

Ed,

This module uses a latching relay and should turn off power to the coil once the relay is fully closed. Therefore you should not expect to see any interference from the relay coils once the relay is closed. Does that satisfy your concern?

http://www.ni.com/pdf/manuals/373649k.pdf

[ehseger]

Frank,

    Are these relays individually controllable?  I ask because if one relay (or a bank of them) are selected to route a signal (my microvolt signal) and somewhere else on the 2529 I change the path of another signal by changing the state of a relay or relays, how much disturbance will I see on the microvolt signal path.  I am not looking for some definitive answer in volts, etc. I just need to kno if anybody has experienced any "control crosstalk" on a board like the 2529.

When the 2529 is in steady state and the microvolt signal is being acquired, I change the routing on another circuit on the 2529, there is a pulse supplied to some of the relay(s) not involved with the microvolt signal, during that pulse, will I expect to see any disturbance on the microvolt signal path.  I believe that in stady-state, this board will be really quiet..

Thanks,

Ed

[Frank-L · Accepted solution]

Ed,

Each relay is individually controllable. (IE you can connect c0->r0 first and c1->r1 second and it will not attempt to re-drive c0->r0). As far as how much disturbance you will see, you can look in the manual (http://www.ni.com/pdf/manuals/373649k.pdf) and find cross talk (snapshot shown below).

As shown in http://zone.ni.com/reference/en-XX/help/375472H-01/switch/2529_relay_replacement/ the relay is a AGQ210A4H. Unfortunately we do not specifically spec noise that might occur from driving an adjacent relay, but I would surprised if it was noticeably large especially considering the insulation resistance of the relay is specced at 1GOhm (https://www.mouser.com/datasheet/2/315/mech_eng_gq-1299323.pdf).

[ehseger]

Frank,

    This is the level of information I need to justify specing this board.  Thanks!