Shunt Circuit Question

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G & G Electric

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I have question about a shunt circuit on an Ansul system, I'll try to keep it short and to the point. Circuit 28 is a shunt breaker, an individual circuit, feeding an oven. It goes through the NO contacts on a relay. That relay coil is held closed by circuit 29. 29 comes off of its breaker, hits a terminal block, and splits. One 29 goes through the NO Ansul system, and comes back to complete the shunt trip circuit when the handle near the oven is pulled. The other 29 goes from the terminal block and holds the relay closed. Also in that relay NO is the new kitchen RTU. My question is - When the handle is pulled and closes the dry contacts in the Ansul system, I know circuit 28 will open due to 29's circuit closing and energizing the shunt coil, but will circuit 29 open as well? I know, it sounds weird. It is a SqD shunt, and it has a sticker on it that leads me to believe the shunt circuit will trip when the shunt breaker trips. If this is correct, then when 29 opens, the RTU will shut down due to the relay being unenergized and returning to its open state. Or I could just run the line side of 28 to energize the coil, and I know then the RTU would shut down due to the shunt circuit 28 opening. Thanks ya'll!
 
From what I read Ckt 29 energizes 28's shut trip via the ANSUL system, but I've read nothing leading me to believe that ckt 29 will open. ( I may be missing something? ) I prefer to keep circuits like this simple, so I would be inclined to feed the coil of the RTU contactor off ckt 28. In fact nothing I read leads me to believe ckt 29 need to be part of the control process at all.

However maybe there is something I'm missing with the fire safety aspect of the code?


Regards,

Doug S.
 
I wish the breaker was here in front of me, I can't remember exactly what it said. After searching the net I found a similar breaker. It energizes the shunt coil when voltage is applied, and the shut will remain open until energized. Now that I think about it, that may be more along the lines of what the sticker read on the shunt breaker. I think I will use 28 to keep the coil closed on the relay. Thanks:)
 
G & G, Circuit 28 is the s.t. breaker, circuit 29 is a standard 1p breaker and will not trip

when the s.t. breaker does. The Ansul system should control the Exhaust Fan and the

Make-up Air and the RTU per the local Fire Marshal.
 
Man, a drawing would be nice!​

Trying to 'read' English as a wiring diagram is difficult. I, too, see no reason circuit 29 should turn off, however.​
 
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Yeah, I abondoned the idea of 29 tripping - all it does is complete the circuit so 28 (the shunt) will trip. I hate going off of cardboard engineered drawings. Fire marshall came by today after lunch, pulled the "in case of fire" handle and the cooking equipment under the hoods shut down, exhaust fans remained on, the MAU and RTU both shutdown :smile:. Sometimes I have bouts of cranial flatulence. And I get those right before I over engineer something. Thanks guys!
 
G & G Electric said:
Yeah, I abondoned the idea of 29 tripping - all it does is complete the circuit so 28 (the shunt) will trip.
Click to expand...
The main advantage of having the trip trigger on its own circuit is that there's no chance of burning out the trip coil.

Some shunt-trips open their coil circuit when they trip, but many don't. Continuous energization can burn up the coil.
 
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