Groups > sci.electronics.components > #6209

Re: Contactors/Relays

From	rickman <gnuarm@gmail.com>
Newsgroups	sci.electronics.design, sci.electronics.components
Subject	Re: Contactors/Relays
Date	2017-10-19 18:48 -0400
Organization	A noiseless patient Spider
Message-ID	<osba4k$4n9$1@dont-email.me> (permalink)
References	(1 earlier) <4rp4uchsbma3k2vlibt6h9hkgr1umc5c3e@4ax.com> <os8kqe$pdl$1@reader2.panix.com> <sk4gucduddh0eih3stfj9fkqrpp39jbp3q@4ax.com> <os9fne$4b4$7@reader2.panix.com> <9gthuclbfqcoobevuakm75vq89l0a78j8l@4ax.com>

Cross-posted to 2 groups.

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legg wrote on 10/19/2017 3:02 PM:
> On Thu, 19 Oct 2017 06:11:58 +0000 (UTC), David Lesher
> <wb8foz@panix.com> wrote:
>
>> legg <legg@nospam.magma.ca> writes:
>>
>>
>>> This 'fail closed' issue may be a misconception. What mode of failure
>>> are you anticipating this to cover?
>>
>> Nope, it's what's needed....
>> Control power drops, relay contacts close.
>
> Where does control power come from?
> I'd expect use a power fail signal to do it's business during a
> hold-up time period.
>
> If there is only control power, then there's nothing to control, so
> the normal state, in that condition, should be your 'fail-safe'
> default.

Are you suggesting the relay needs to be powered from the contacts and it 
needs to *remember* the state it was last in when control power fails? 
Seems simpler to just power the coil from the control side and use a NC 
relay.  No small part of the use of relays comes from the isolation. 
Powering the relay from the load side means you have to start all over again 
with an isolation barrier.

-- 

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

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Thread

Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-14 18:16 +0000
  Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-14 15:38 -0400
    Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-18 22:32 +0000
      Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-18 23:11 -0400
        Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-19 06:11 +0000
          Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-19 15:02 -0400
            Re: Contactors/Relays rickman <gnuarm@gmail.com> - 2017-10-19 18:48 -0400
              Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-19 23:02 -0400
                Re: Contactors/Relays rickman <gnuarm@gmail.com> - 2017-10-20 00:49 -0400
                Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-20 12:03 -0400
                Re: Contactors/Relays rickman <gnuarm@gmail.com> - 2017-10-20 13:17 -0400
                Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-21 09:52 -0400
                Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-22 06:25 +0000
                Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-26 05:00 +0000
                Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-29 13:23 -0400
                Re: Contactors/Relays Michael A Terrell <mike.terrell@earthlink.net> - 2017-10-30 16:04 -0400
                Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-11-03 06:07 +0000
      Re: Contactors/Relays upsidedown@downunder.com - 2017-10-19 13:00 +0300
        Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-22 06:23 +0000
        Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-26 05:04 +0000
  Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-14 15:52 -0400
    Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-19 06:03 +0000
  Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-14 16:20 -0400
    Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-19 06:04 +0000
      Re: Contactors/Relays rickman <gnuarm@gmail.com> - 2017-10-19 03:49 -0400
        Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-22 06:18 +0000
          Re: Contactors/Relays rickman <gnuarm@gmail.com> - 2017-10-22 03:57 -0400
  Re: Contactors/Relays Hul Tytus <ht@panix.com> - 2017-10-14 21:20 +0000
    Re: Contactors/Relays David Lesher <wb8foz@panix.com> - 2017-10-19 06:07 +0000
      Re: Contactors/Relays legg <legg@nospam.magma.ca> - 2017-10-19 23:11 -0400
  Re: Contactors/Relays John Larkin <jjlarkin@highlandtechnology.com> - 2017-10-14 16:43 -0700
  Re: Contactors/Relays upsidedown@downunder.com - 2017-10-15 10:20 +0300
  Re: Contactors/Relays Neon John <no@never.com> - 2017-10-15 09:49 -0400

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