# Motor starter hvac



## WronGun (Oct 18, 2013)

So this is a job I’m going to Friday, the client tried to wire it himself and now they want me to verify it. 

I’m not an expert on this but it seems we have the lines and loads terminated.

I’m really not sure where the coil power comes from or what controls it. 

But I’m confused on the rib relay. It has both N/O and N/C leads that can be used. What could this possibly go to ? 

I’m thinking this would either close the coil or it’s an auxiliary circuit for some device.










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## splatz (May 23, 2015)

The RIB is easy because they have a good web site and good documentation. 
from RIBU1C.pdf (functionaldevices.com)









This is the closest I could find to the correct document because Siemens' web site is such a **** heap
from 969 2170-10_DS 01.fm (siemens.com)











So it looks like blue to 1, yellow to 2, orange to 3. 
(not so sure about the stop)


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## 460 Delta (May 9, 2018)

Looks like the contacts aren’t connected on the ESP-200 overloads. Set the trip rate to whatever rate the manufacturer asks for. I generally turn on phase loss, imbalance, and ground fault also.


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## WronGun (Oct 18, 2013)

splatz said:


> The RIB is easy because they have a good web site and good documentation.
> from RIBU1C.pdf (functionaldevices.com)
> 
> View attachment 170049
> ...


I did pull up these diagrams online, yours is the closest ive seen to my configuration. What could the relay control though ? 


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## CMP (Oct 30, 2019)

From the color code used, it looks like it controls the motor starter from some other signal we can’t see.


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## WronGun (Oct 18, 2013)

460 Delta said:


> Looks like the contacts aren’t connected on the ESP-200 overloads. Set the trip rate to whatever rate the manufacturer asks for. I generally turn on phase loss, imbalance, and ground fault also.


I do have the recommended trip rate figured. 

Which contacts are you seeing not connected ? 


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## just the cowboy (Sep 4, 2013)

Mark the wires and draw a print of what you have.
Take better pictures so we can see the termination points on the contactor.
What is it doing the RIB may be bringing the reset in.

Make it right with print and numbers for the next guy.


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## 460 Delta (May 9, 2018)

WronGun said:


> I do have the recommended trip rate figured.
> 
> Which contacts are you seeing not connected ?
> 
> ...


The N/C set at the lower left of the unit. The RIB is likely being hit with 24 volt and the Starter coil looks like the center jumpers are in so it’s set for line voltage, 230 or 460. So you’ll need an interposing relay, short of a 24 volt coil for the starter, this is what you have to do.

Edit for clarity.


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## WronGun (Oct 18, 2013)

460 Delta said:


> The N/C set at the lower left of the unit. The RIB is likely being hit with 24 volt and the Starter looks like the center jumpers in so it’s set for line voltage, 230 or 460. So you’ll need an interposing relay, short of a 24 volt coil for the starter, this is what you have to do.


So you are thinking the rib controls a remote reset.


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## splatz (May 23, 2015)

If the RIB isn't starting and stopping it, what is?


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## splatz (May 23, 2015)

WronGun said:


> So you are thinking the rib controls a remote reset.
> 
> 
> Sent from my iPhone using Tapatalk


There are wires already landed on the remote reset terminals.


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## WronGun (Oct 18, 2013)

splatz said:


> There are wires already landed on the remote reset terminals.


Ya the picture is horrible, it was sent to me. 

It looks like the A3 and A4 are landed, but the 
N/C and N/O looks open. 


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## oldsparky52 (Feb 25, 2020)

Okay, what is "RIB"? 

Is that enclosure rated for that starter?


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## Wirenuting (Sep 12, 2010)

oldsparky52 said:


> Okay, what is "RIB"?
> 
> Is that enclosure rated for that starter?


Relay in a box. 
Functional Devices make many styles, good stuff


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## micromind (Aug 11, 2007)

The RIB is short for 'Relay In A Box'. It's the thing outside the starter on the lower right. 

Most HVAC controls are 24AC so most likely the RIB relay was used to make the 24AC control the 120 or 240 starter coil.


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## 460 Delta (May 9, 2018)

WronGun said:


> So you are thinking the rib controls a remote reset.
> 
> 
> Sent from my iPhone using Tapatalk


No, I’m thinking that the RIB is taking 24 volt from somewhere else and switching the 230 or 460 line voltage used for control voltage on that Furnas starter.


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## WronGun (Oct 18, 2013)

460 Delta said:


> No, I’m thinking that the RIB is taking 24 volt from somewhere else and switching the 230 or 460 line voltage used for control voltage on that Furnas starter.


Confused because the line side of the relay is spliced in that box leaving me with the 24v side to land somewhere on this starter. The 1,2,3 splatz mentioned made sense to me or either the N/O or N/C contacts 

The Rib wasn’t changed out on the starter. 


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## CAUSA (Apr 3, 2013)

Need clearer photos and HVAC unit data plate.

what’s the establishment building function.?


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## 460 Delta (May 9, 2018)

WronGun said:


> Confused because the line side of the relay is spliced in that box leaving me with the 24v side to land somewhere on this starter. The 1,2,3 splatz mentioned made sense to me or either the N/O or N/C contacts
> 
> The Rib wasn’t changed out on the starter.
> 
> ...


The reason the wiring seems off is that they got in way over their heads and couldn’t make it work. Then they called an electrician (you).

Figure out the process and controls scheme, then make it work.


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## WronGun (Oct 18, 2013)

CAUSA said:


> Need clearer photos and HVAC unit data plate.
> 
> what’s the establishment building function.?


This is a federal site. It’s a national historic visitor center. Mainly a gift shop, historic exhibits and a theater room. This has been common over the years, facilities thinking they can fix these things. It’s like the Wild West in some of these buildings located in the midst of a very strict state in terms of code. They are exempt from inspections or permits for any work. 

I was trying to get a better understanding before showing up Friday but realized I’m short on information. 

The starter part I understand, the relay part I just don’t have all the info. It looks like they landed the starter but got confused on the rib.

Apparently it was never turned on, and decided to call to verify the wiring. This building isn’t very high tech, I can’t imagine it being very complicated. I suppose you could say it was pretty high tech when it was partially done over in or around the early 80’s 


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## splatz (May 23, 2015)

WronGun said:


> Confused because the line side of the relay is spliced in that box leaving me with the 24v side to land somewhere on this starter. The 1,2,3 splatz mentioned made sense to me or either the N/O or N/C contacts
> 
> The Rib wasn’t changed out on the starter.





splatz said:


> So it looks like blue to 1, yellow to 2, orange to 3.


On second thought this is probably no good. Energizing the 24V coil of the RIB would be like pressing start and stop at the same time.


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## WronGun (Oct 18, 2013)

splatz said:


> On second thought this is probably no good. Energizing the 24V coil of the RIB would be like pressing start and stop at the same time.


I contacted the supervisor. 

He said there are 3 identical RTU’s with same wiring and I’ll be able to look at the other 2 to figure this one out. This may speed up the process. 


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## just the cowboy (Sep 4, 2013)

WronGun said:


> I contacted the supervisor.
> 
> He said there are 3 identical RTU’s with same wiring and I’ll be able to look at the other 2 to figure this one out. This may speed up the process.
> 
> ...


I'll repeat draw it out, this is something you need to improve on. 
If you don't have my book here it is. Whole section on prints


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## WronGun (Oct 18, 2013)

It was 2 and 3 on the contacts. The rib goes to a Tstat. Used common and n/o on rib capped the n/c. 

Tested and all worked. 


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## Almost Retired (Sep 14, 2021)

2 and 3 makes perfect sense, the industry standard for seal in contacts for motor starters


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