Re: [foxboro] FBM207B contact sense
- From: Terry Doucet <doucet427@xxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Tue, 1 Feb 2011 23:39:06 -0500
Joseph,
Why do the relay contacts require a minimum of 72 mW? When the relay contact
is closed, it is a short circuit as far as the FBM207B is concerned and the FBM
sensing the shiort circuit sets its output TRUE in the contact input block. I
have never been concerned with the amount of current flowing in the loop. The
FBM207B can be open circuited, shorted or shorted to ground without any damage
to the FBM. The contact material can affect the life of the relay but I
specified a lot of relays to drive inputs into FBM07's and FBM207's and almost
always just used the plant standard relay.
Terry
> From: Joe@xxxxxxxxxxxxx
> To: foxboro@xxxxxxxxxxxxx
> Subject: [foxboro] FBM207B contact sense
> Date: Tue, 1 Feb 2011 22:44:21 -0500
>
> Folks,
> Anybody using the FBM207B contact sense for their contact inputs? This
> version provides 24 vDC, 2.5 maDC (max) to wet the contact inputs. Sort of
> a light weight at only 60 mW. The relays we planned to use (silver-plated
> contacts) require a minimum of 72 mW. Just curious what others have used
> with this FBM short of the gold plated contact option.
>
> Thanks.
>
> Joseph M. Riccardi
>
> Senior I&C Engineer
>
> Bechtel Parsons Blue Grass Team
>
>
>
>
>
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