Relay to power microwave

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  #1  
Old 01-07-13, 12:14 PM
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Relay to power microwave

I'd like to use a relay to power an 800 watt microwave. Would this relay be sufficient?
http://ribrelays.com/images/product/...s/RIB01BDC.pdf
 
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Old 01-07-13, 12:35 PM
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That could work... but why would you want to cut the power to your microwave?
 
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Old 01-07-13, 12:45 PM
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Why do you want to relay the microwave? Curious.
 
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Old 01-07-13, 12:58 PM
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We want to control access. People will swipe their access card and the system will close the dry contacts on the relay for a set period of time. --Would that relay be able to handle the load?
 
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Old 01-07-13, 01:05 PM
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There have been some reports of countertop appliances randomly catching fire, even when not in use. Maybe having all countertop receptacles on a time clock that would require an operator input to power up with timed shutdown is something to consider.

I personally have never had the experience but there are a lot of things that HAVE happened to others that I have not experienced.
 
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Old 01-07-13, 05:41 PM
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We want to control access. People will swipe their access card and the system will close the dry contacts on the relay for a set period of time
Interesting......You gonna charge your kids to use the microwave?
 
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Old 01-07-13, 05:53 PM
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That relay is a good choice for that application.
 
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Old 01-08-13, 04:18 AM
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It should be more then capable to handle the microwave.
I would caution that the microwave's useful life may be shortened by continuing to kill the main power to it.
 
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Old 01-08-13, 04:36 AM
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That relay might not be your best choice..
The contacts will handle the current but you need one whose coil operates at 24 volts.

A swipe card system outputs low voltage rather that the 120 volts that RIB relay uses.
Like this.
 
  #10  
Old 01-08-13, 08:44 AM
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Good point Greg

The 110volt relay the OP suggested uses a "dry" contact as its activation but it doesn't say what voltage that dry contact is actually switching.
Most access systems I've worked with use a relay to activate the device which should interface correctly.
 
  #11  
Old 01-09-13, 05:15 AM
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In that case the best way to connect the relay to the existing swipe system is to use a buffer relay; a relay to control the relay. This prevents voltage from the microwave relay from interfering with the contact closures in the swipe system.
 
  #12  
Old 01-09-13, 06:27 AM
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I have installed card access systems on doors, vending machines, elevators, laundry machines and I know it's a substantial investment per location. I have never had a request for a microwave though. It just seems like a lot of trouble and expense to protect a microwave. I think we are all curious, can you tell us a little more? I assume this is a work environment? lunchroom? How is microwave privilege determined? Is it based on seniority? Managerial level? Pay scale? Do entry level employees start out on the toaster oven and work their way up to the microwave?
 
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Old 01-09-13, 02:22 PM
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The reason i chose this relay was because it should not need a second relay to protect the dry contact circuit on the access control hardware. From the manufacturers page description of this series of relays:

The Dry Contact Input RIB series offers all the advantages of the standard RIB line; plus, it can be activated by a wide range of dry-contacts such as thermostats, switches, other relays, solid-state switches, etc. The Dry Contact Input RIB provides the low-voltage (Class 2) power needed to activate the relay (self-powered) - just close the dry-contact input. The power to energize the relay can be brought to the relay on a separate pair of wires along with the control output of the controller, or can be a local power source near the relay. The relay contacts are isolated from the input power and the dry contact input; thus, they can be wired to switch any other power-load or low-voltage load (see specifications for contact ratings). One model can be used for many installations (model RIB21CDC can operate from any voltage from 120Vac - 277Vac; see specifications for the input power of other models).
http://www.functionaldevices.com/building-automation/relays.php
 
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Old 01-10-13, 12:04 AM
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it can be activated by a wide range of dry-contacts such as thermostats, switches, other relays, solid-state switches, etc. The Dry Contact Input RIB provides the low-voltage (Class 2) power needed to activate the relay (self-powered) - just close the dry-contact input.
You should be set to go there.
 
  #15  
Old 01-10-13, 12:42 AM
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I'll throw out one possible wrinkle. Is the microwave 800 W of cooking power or is that the nameplate power draw? If its cooking power, you probably need significantly more electrical power (maybe 1000-1300 watts).
Further, a microwave is a capacitive load, meaning that you may need to use one of theratings for the contacts besides the resistive load ratings. It's really a power factor and surge current question.
 
  #16  
Old 01-10-13, 04:51 AM
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The Dry Contact Input RIB provides the low-voltage (Class 2) power needed to activate the relay (self-powered) - just close the dry-contact input.
That's exactly why I made my point about buffering. If that relay is the only thing on the dry contacts from the card swiper, then go with it. If there are other devices on the contacts, such as door maglocks, the voltage from the microwave relay could interfere with the other systems.
 
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