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Discussion Starter #1
Have 4 new exhaust fans in differenent places of the building about 100 feet apart. 480vac 3phase 2hp motors on each. Pulling from a 480vac bus duct. How would do this run? Separate combo starters for each exhaust fan in a easily accessible location? Would you put anything else in the circuit?
 

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Using buss disconnect transitions or buss to panel then feed the starters?
Location depends. Nice to have that type of equipment coming from one MCC but anything is possible. There are many many (police academy) options
 

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Old Grumpy Bastard
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Do you have a semi central spot for a sub panel and the starters that is convenient?
 
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Local disconnects? I think exhaust fans need them not sure.
 

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Probably, the most cost effective method, with small motors as these, would be to assemble a panel with a local disconnect,all of the individual motor fusing, the starters, and the control devices. This would only require one circuit from the buss duct. If these fans are for general building ventilation, as in that they are not stopped and started often, you could use IEC starters to save space in the panel.

A 2 HP motor on 480 would only pull about 3.5 amps each. So four buss disconnects would be over kill.
 

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Probably, the most cost effective method, with small motors as these, would be to assemble a panel with a local disconnect,all of the individual motor fusing, the starters, and the control devices. This would only require one circuit from the buss duct. If these fans are for general building ventilation, as in that they are not stopped and started often, you could use IEC starters to save space in the panel.

A 2 HP motor on 480 would only pull about 3.5 amps each. So four buss disconnects would be over kill.
i agree with Varmit don't over think it this small motors does not require to much design
 

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electrorick
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just the cowboy


that horse didn't throw me !
that's just the way I get offem !
 
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Discussion Starter #11
When you say local disconnect. Does that mean each motor with a within sight disconnect? Or just 1 disconnect centrally located? Theres no way to centrally locate it to be within sight of each motor. Or 4 disconnects for each individual motor centrally located? We have a open spot to centrally locate. When you say panel what kind do you mean?
 

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Depending on your plant rules/ specs (if any exist) as long as the starter panel disconnect is lockable in the off position, this could be the lock out point for all four motors. Otherwise, a local disconnect would be required at or "within sight of" each motor.

The "panel" that I am speaking of would be a Hoffman type industrial enclosure of a type that would suit the environment - NEMA 1, NEMA 12, etc. You purchase a separate back panel, for the enclosure, to mount and assemble and wire your components. You would need : a disconnect for the panel, individual motor fusing, the starters and overloads and a small control power transformer. Your manual control devices- push buttons or selector switches, could be installed in the panel door, or be installed close to each fan position with the control wires being routed to the fan control panel.
 

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Chief Flunky
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Depending on your plant rules/ specs (if any exist) as long as the starter panel disconnect is lockable in the off position, this could be the lock out point for all four motors. Otherwise, a local disconnect would be required at or "within sight of" each motor.

The "panel" that I am speaking of would be a Hoffman type industrial enclosure of a type that would suit the environment - NEMA 1, NEMA 12, etc. You purchase a separate back panel, for the enclosure, to mount and assemble and wire your components. You would need : a disconnect for the panel, individual motor fusing, the starters and overloads and a small control power transformer. Your manual control devices- push buttons or selector switches, could be installed in the panel door, or be installed close to each fan position with the control wires being routed to the fan control panel.


Why not just use a combination starter panel? Everything is already prewired including start/stop buttons.

The “within sight of” rule has an exception for supervised installations where qualified workers work on it. No local disconnects needed.

Wiring wise depends on plant rules. Near a roof so type AC or MC is probably the cheapest and fastest. PVC a little more money and time, and IMC or rigid the slowest. If corrosion and moisture is an issue I’d stick with PVC and THWN-2.


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My approach I think would be similar to @varmit explanation. I would take a single circuit from the buss to a control panel. In the panel I would have multiple starters; depending on the requirements for running (on / off, start/ stop), interlock, air flow, temperature, etc I might just put in a terminal strip and wire directly or I might use a programmable relay or even a small PLC.

This approach will determine if you are controlling at line voltage or a lower voltage. I would then put a HP rated 3 pole toggle switch at each fan for maintenance; something like a Hubbell HBL7810D which you can get a variety of lockable enclosures for depending on your environment.

The hard work is not getting the fans to run, but is how they are they controlled? This will actually have a larger impact on your design then the physical and electrical requirements of each fan.

Cheers
John
 

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My approach I think would be similar to @varmit explanation. I would take a single circuit from the buss to a control panel. In the panel I would have multiple starters; depending on the requirements for running (on / off, start/ stop), interlock, air flow, temperature, etc I might just put in a terminal strip and wire directly or I might use a programmable relay or even a small PLC.

This approach will determine if you are controlling at line voltage or a lower voltage. I would then put a HP rated 3 pole toggle switch at each fan for maintenance; something like a Hubbell HBL7810D which you can get a variety of lockable enclosures for depending on your environment.

The hard work is not getting the fans to run, but is how they are they controlled? This will actually have a larger impact on your design then the physical and electrical requirements of each fan.

Cheers
John
Why not one starter to control all four fans so that they are all either on or all off? So there would be one feed from the bus to the starter, one feed out from that starter either to a local junction box with 4 feeds out of it and terminal jumpers from the feed to each fan's supply, or splice the wires in a fitting for each starter where ever you put in a pipe tee, or at each starter, depending on routing and layout. Then have a lockable disconnect switch at each fan for maintenance.
 

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Why not one starter to control all four fans so that they are all either on or all off? So there would be one feed from the bus to the starter, one feed out from that starter either to a local junction box with 4 feeds out of it and terminal jumpers from the feed to each fan's supply, or splice the wires in a fitting for each starter where ever you put in a pipe tee, or at each starter, depending on routing and layout. Then have a lockable disconnect switch at each fan for maintenance.
Agreed if that is the way they are supposed to be controlled. I am not clear on how they are supposed to operate; as a group, semi-independently or totally independently. If they were all running as a group I might consider a simple manual switch at each fan with a heater in it for protection and not have a set of OLs in the starter.

Again it is all in how they are to be controlled.

Cheers
John
 

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Discussion Starter #18
There just going to be used as general building ventilation exhaust fans. There leaving how they are going to be controlled up to be. Planned on just a start and stop to control them but now considering other options. All of our older fans in other building are just on or off. Is it common to use airflow or temperature to control these fans?
 

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Is it common to use airflow or temperature to control these fans?
Anything is common if it is required as part of process or environmental control. As an example as part of an ISO requirement a building may be required to have so many air changes (exchanges) in an hour. But that requirement may only apply when a specific process is in operation.

As in another thread, there maybe a requirement just to get the heat out of an area once it rises to a specific temperature. That may involve a staged approach that will start one fan at a time until the desired temperature is reached.

In poultry barns there is a combination of temperature and speed control as there is a pretty specific temperature that must be maintained and little room for deviation.

Cheers
John
 

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Anything is common if it is required as part of process or environmental control. As an example as part of an ISO requirement a building may be required to have so many air changes (exchanges) in an hour. But that requirement may only apply when a specific process is in operation.



As in another thread, there maybe a requirement just to get the heat out of an area once it rises to a specific temperature. That may involve a staged approach that will start one fan at a time until the desired temperature is reached.



In poultry barns there is a combination of temperature and speed control as there is a pretty specific temperature that must be maintained and little room for deviation.



Cheers

John


Yup. Find out what the requirements are from the customer (if there even are any) and THEN ask for recommendations on how to implement. As you see we can do NASA to poultry barns. The trick is you have to figure out which one you are working in.


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