Re: [foxboro] FBM207B contact sense
- From: "Brown, Stanley" <stan.brown@xxxxxxxxxxxxxxxxx>
- To: "foxboro@xxxxxxxxxxxxx" <foxboro@xxxxxxxxxxxxx>
- Date: Wed, 2 Feb 2011 13:59:15 -0500
Hay if you have one of these $xoensive Foxboro support contract, the
incremental cost should be $0 :-)
> -----Original Message-----
> From: Stan Brown [mailto:stanb@xxxxxxxxx] On Behalf Of Terry Doucet
> Sent: Wednesday, February 02, 2011 12:04 PM
> To: foxboro@xxxxxxxxxxxxx
> Subject: Re: [foxboro] FBM207B contact sense
>
> Most of my relay work was intended to separate the (expensive) FBM's
> from other electrical products so that an electrician working on a
> (usually 120V ) device who makes a mistake, does not put 120 V anywhere
> near the FBM's. So relays were located in close proximity to the
> FBM's. The rack rooms were air conditioned and filtered so that there
> was no corrosion. Corrosion monitoring was part of their maintenance.
> Often, my relay was driving a starter coil or isolating a motor status
> contact from the motor control center. But even if I had a field
> contact (tank level switch) I would bring the contact to a relay and
> then that relay would go to the FBM. These relays were about $50 each
> so much cheaper than a blown FBM.
> Terry
>
> > To: foxboro@xxxxxxxxxxxxx
> > Subject: Re: [foxboro] FBM207B contact sense
> > From: corey.clingo@xxxxxxxx
> > Date: Wed, 2 Feb 2011 10:38:41 -0600
> >
> > If I had to guess, this relay is not sealed, or gold-plated, and it's
> a
> > CYA for them to account for any surface corrosion that may wind up on
> the
> > contacts and increase the resistance.
> >
> > Like I said, we have not had problems when the relays are mounted in
> a
> > relatively climate-controlled environment, but if you want to be
> sure, for
> > some years down the road, you'll have to explore other options.
> >
> >
> > Corey
> >
> >
> >
> >
> >
> > From:
> > "Joseph M. Riccardi" <Joe@xxxxxxxxxxxxx>
> > To:
> > <foxboro@xxxxxxxxxxxxx>
> > Date:
> > 02/02/2011 09:23 AM
> > Subject:
> > Re: [foxboro] FBM207B contact sense
> > Sent by:
> > foxboro-bounce@xxxxxxxxxxxxx
> >
> >
> >
> > Terry,
> >
> > The 72 mW rating is in the published spec for the A-B relay. I am
> > guessing
> > that all contact closures are not equal, some have a higher
> resistance
> > than
> > others (i.e., silver-plated vs. gold-plated). With lower power
> sources
> > like
> > the FBM207B, this voltage drop across the contact becomes more
> > significant.
> > I just never realized how significant until matching the FBM207B
> power
> > output spec published to the published A-B relay minimum power
> > requirements
> > across the contact. The output of the FBM207B is current limited to
> 2.5
> > maDC because it supplies the 24 vDC source.
> >
> > I thought the same way you do until someone started reading the
> specs.
> >
> > Joseph M. Riccardi
> >
> > Senior I&C Engineer
> >
> > Bechtel Parsons Blue Grass Team
> >
> >
> >
> >
> >
> >
> >
> >
> _______________________________________________________________________
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> Process
> > Systems (formerly The Foxboro Company). Use the info you obtain here
> at
> > your own risks. Read
> http://www.thecassandraproject.org/disclaimer.html
> >
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>
>
>
> _______________________________________________________________________
> This mailing list is neither sponsored nor endorsed by Invensys Process
> Systems (formerly The Foxboro Company). Use the info you obtain here at
> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
>
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