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Last Post 08/15/2013 10:54 AM by  Tony Hodges
current sensing relay
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Jon Beaumont
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08/12/2013 7:44 PM
    Hello, I am trying to come up with a system that can sense current lose in heaters. I was thinking that a current sensing relay would be ideal...using the relay to turn on LED lights to inform operators of a heater lose and thereby possibly saving a run...this application would be on an autoclave, I'm just concerned that the heaters basically turn on and off to maintain temperature during process an that this would cause false alarms, also the autoclaves themselves do not run 24hrs a day...how would a current sensing relay react with the autoclave in an idle state/no heat being applied? Any help would be greatly appreciated.
    Tony Hodges
    CRM Staff
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    08/13/2013 9:24 AM
    Dear Sir,

    I have attached one of our application guides for your review. Circuit "B" is appropriate for your application. Thank you for your business.
    Attachments
    Jon Beaumont
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    08/13/2013 10:45 AM
    Thanks Tony, for the reply. I checked out the link you gave me and saw something I neglected to put in my post...the heaters for this autoclave have 2 legs which are controlled with an SCR...these are the heaters that open most frequently and therefore are the primary reason for the application...looks like circuit "B" won't function with heaters using an SCR... sorry I didn't include originally...I didn't know it was relevant...that said, is there anything that would work with this type of application... there are 2 heaters with 3 legs per heater, only 2 legs on the primary are SCR controlled, all other legs go directly to the heaters...I need to monitor each leg. I appreciate your help...thank you
    Tony Hodges
    CRM Staff
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    Posts:154


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    08/13/2013 1:31 PM
    If the SCR is an on off control then our relay should work. If it is a phase angle fired control then our relay will not work.
    Jon Beaumont
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    08/13/2013 5:13 PM
    Thanks again Tony, just checked and the scr is an on off control...so I'm good there. I want to make sure I order the right item...I want the relay to turn on some 120v LED lights when a leg is blown, also these are 80amp heaters...is there any specific model of 4395 that i need to get? Which type would be better suited, the EL or the LL type of relay? Again, thank you
    Tony Hodges
    CRM Staff
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    Basic Member
    Posts:154


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    08/15/2013 10:54 AM
    Dear Sir,

    When the -LL version is used, each time the relay changes state the supply voltage will have to be disconnected to reset the unit. This is good for applications where a visual inspection is necessary to find out why the relay changed state.

    The -EL version will reset automatically once current is detected above the set point.
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