definite purpose contactor

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nizak

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Thoughts please. I have a definite purpose contactor that I intend to install, the coil will be energized and the contacts "made" indefinetly until an Ansul switch calls for them to be opened.
(suppression system activated). Will this indefinite holding of the coil cause this to wear out quicker than if it were to let's say be energized for only10-12 hours.a day.The actual load thru the contacts would be 10-12 hrs a day.Thanks
 
Why not order it normally closed and change the connection at the Ansul switch?

Ansul activation closes the control circuit, the control circuit powers the coil and opens the contator.
 
In the past, I've tended to favor an open type double throw contactor to control the fan and make up air with the ANSUL on smaller hoods. Powering the contactor with the ANSUL switch drops out the make up air and brings on the fan. The 'normal' switch for the makeup air is in series (before) the contactor, and the 'normal' switch for the fan is in parallel with the contactor.

XL-2DR61.JPG
 
Appears that without a specific set of drawings for a system(specs and equipment) there are a host of ways to wire hood systems. Ask 10 people how to shut down a system and I'd bet you'd get at least 8 different answers. Thanks to all for the insight.
 
nizak said:
Appears that without a specific set of drawings for a system(specs and equipment) there are a host of ways to wire hood systems. Ask 10 people how to shut down a system and I'd bet you'd get at least 8 different answers. Thanks to all for the insight.
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You're 100% correct. The end goal is still the same. If you have a big hood with lots of stuff going on, I'd highly recommend one of Greenheck's integrated hood panels designed for this purpose. Let me see if I can find that brochure. I've used two in the past; both for schools.

Here you go:
brochure: http://greenheck.com/pdf/kitchen/KFCCApril2007.pdf
wiring diagram: http://www.greenheck.com/pdf/kitchen/Wiring_KFCCArrgW-MUA.pdf
 
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mdshunk said:
The 'normal' switch for the makeup air is in series (before) the contactor, and the 'normal' switch for the fan is in parallel with the contactor.
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Every microswitch I've seen in hood systems are rated for 20a. I like using a single micro for everything. Here's an example:

Before.jpg


After.jpg

I can do the same thing when the intake and exhaust have separate switches, too. I'll have to draw and upload that one.
 
LarryFine said:
Every microswitch I've seen in hood systems are rated for 20a. I like using a single micro for everything.
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Nice, simple and reliable, but really has a problem with 3 phase fans which is what I run into.


That said I am lucky as there has always been a premade control panel that I just had to connect to the Ansul panel.
 
LarryFine said:
Every microswitch I've seen in hood systems are rated for 20a. I like using a single micro for everything. Here's an example:

​

After.jpg

I can do the same thing when the intake and exhaust have separate switches, too. I'll have to draw and upload that one.
Click to expand...

Is a microswitch, a Fan rated motor toggle switch, please define that ! ? ?
 
cadpoint said:
Is a microswitch, a Fan rated motor toggle switch, please define that ! ? ?
Click to expand...
The miroswitch is in the upper right of the ansul cabinet, and has C, NC, and NO pigtails. It will change positions when the bottle fires off.
 
nizak said:
Thoughts please. I have a definite purpose contactor that I intend to install, the coil will be energized and the contacts "made" indefinetly until an Ansul switch calls for them to be opened.
(suppression system activated). Will this indefinite holding of the coil cause this to wear out quicker than if it were to let's say be energized for only10-12 hours.a day.The actual load thru the contacts would be 10-12 hrs a day.Thanks
Click to expand...



Many pieces of equipment are designed so that the relay coil is normally energized and drops out on an alarm or failure. This is designing to be fail-safe.

If the relay coil fails the system goes into alarm.
If you use a normally closed contact and energize the coil on alarm ,then what happens if the relay coil is defective? Or what is someone inadvertantly turns off the controller?
 
As far as the "manual" reset that is sometimes required, I can see for instance manually resetting a shunt trip breaker, but what if the microswitch is all that is controlling your contactor. Is re-cocking the trip mechanism and putting the micro back to it's original position considered a manual reset?
 
iwire said:
Nice, simple and reliable, but really has a problem with 3 phase fans which is what I run into.
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That's an easy one: wire the contactor coils in the same place.
That said I am lucky as there has always been a premade control panel that I just had to connect to the Ansul panel.
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I've never been handed one, but some new hoods come with switches installed and wired to topside J-box(es). I usually make my own to suit the equipment.

Here's a couple of pics from one of my recent ones. New church building, fans were wired directly to the breakers (3p exh., 1ph int.):

Here's the head, but this company usually uses a polished cast aluminum-housed one.

Image008.jpg

Here's the switches for the fans and for the lights, and the manual-reset box.

Image009.jpg

This is my box. Three MC's on the right come from the panel (I had to re-route them), three on the left out to four receptacles (one is a MWBC), switched by a 4-pole contactor.

Top MC's, left to right, are: 3-ph to exhaust motor; 3-ph from panel; 1-ph to intake motor; 1-ph from panel; and hot from lighting ckt., which powers the contactors, gas solenoid, and horn/strobe.

On the bottom, left to right: to gas valve solenoid; to hood lights; 1/2" flex in-wall to switches; and EMT to the horn/strobe, control head, and gas reset box.

Image011.jpg


Comments welcome. (As if I could stop them! :wink:)
 
cadpoint said:
Is a microswitch, a Fan rated motor toggle switch, please define that ! ? ?
Click to expand...
How about a pic:
Microswitch.jpg

There are usually two of these installed in the control head of the supression system. They're for us to play with. :smile:
 
nizak said:
As far as the "manual" reset that is sometimes required, I can see for instance manually resetting a shunt trip breaker, but what if the microswitch is all that is controlling your contactor. Is re-cocking the trip mechanism and putting the micro back to it's original position considered a manual reset?
Click to expand...
No, the 'manual reset' is a box that contains a self-latching relay, like a start button, that requires a deliberate action so the operator also lights the pilots.

If the supression system is re-cocked, the fans may return to normal manual operation, but the gas won't flow until the reset box is, well, reset.
 
ELA said:
Many pieces of equipment are designed so that the relay coil is normally energized and drops out on an alarm or failure. This is designing to be fail-safe.

If the relay coil fails the system goes into alarm.
If you use a normally closed contact and energize the coil on alarm ,then what happens if the relay coil is defective? Or what is someone inadvertantly turns off the controller?
Click to expand...

ELA that is all very true but that is strictly a design issue not a code issue.

We are not talking about sending an alarm signal, this just drops out a fan, also connected to the Ansul is often shunt trip breakers to kill the power to the under hood equipment.

As far as the control circuit I use a breaker lock or use a circuit that is part of something they will not do without. :)
 
iwire said:
ELA that is all very true but that is strictly a design issue not a code issue.

We are not talking about sending an alarm signal, this just drops out a fan, also connected to the Ansul is often shunt trip breakers to kill the power to the under hood equipment.

As far as the control circuit I use a breaker lock or use a circuit that is part of something they will not do without. :)
Click to expand...

Bob,

Who said this thread had to be about code? I was commenting on the OPs question about relays being constantly energized. I did not see where the OP referenced anything about code?
 
In Larry's picture above, he's using the reset relay to only reset the gas valve (I think). Honeywell is the OEM for the ANSUL brand reset relay. If you buy that reset relay directly from Honeywell, it will not say "Gas Valve Reset Relay" on the front. It will only say something like "press to reset". For that reason, I buy the reset relay right from Honeywell, and use that reset relay to reset everything that tripped off when I'm doing it all with contactors, and not limit it to just the gas valve.


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