Generac ATS question

[FREEBALL]

I installed a generac 22kw and ATS w/ load shedding in a commercial setting. I want to now further shed some load without the load shedding modules. I am using 120 v contactors to shed some load but the panel Im designating the generator panel has 9 shorelines for ambulances. I would like to run from the line side of the sensing fuses on the ATS, a 120v circuit, fuse it at 2 amps in the ATS, to hold a set of contactors that would feed the shorelines from the panel. The panel is 110 ft away from ATS. So when the power drops out, the generator comes on the shorelines will not be powered. Does this sound viable and does anyone else have a better idea. I thought of using sort of a manual shunt that when the power goes out the shorelines would need to be reset, but there may not be personell on site at that time to manually reset.

Thanx again for any insight.

 

[ActionDave]

You are on a bold adventure. The easy thing to do is find something manufactured and buy it. That's not good enough in this case. I think you have come up with a viable option. Hook it up, test it, repeat.

 

[kwired]

Does transfer switch have an aux contact, or can be fitted with one?

If driving this from sensor circuit you could have a situation where you are running on standby yet there is utility voltage or partial utility voltage and it would pull in the contactor you are using and then the generator would be attempting to supply what you desired to lock out.

You could use normally closed contactor points and control the contactor from the generator output - but this would shed those loads when the unit is "exercising" unless you add more control logic to prevent this from happening.

 

[ATSman]

Keep It Simple S - - - - - (KISS)

Keep It Simple S - - - - - (KISS)

I agree with Kwired. You need to supply the load shed circuit from the switch position logic, in other words when the ATS is in the emergency position, load shed is active. If you supply it from the utility line then when the power comes back and ATS is still in emer position, the load shed circuit would reset and gen becomes overloaded.
All ATS units have aux contacts to indicate switch position. Wire the coil of the LS contactor in series with this contact that is closed with ATS in emer. This is simple and provides auto reset of shedded load contactor when ATS transfers back to normal.
This also prevents loadshedding when only the generator is set to "exercise" on a routine schedule.

 

[FREEBALL]

Thanx for the replies, the ATS does not have a set of contacts like the 400 amp rated does. The generator cold weather accessories, if installed, feed off of the 240 volt sensing circuit at the generator so I do not see an issue with tapping before the fuses in the ATS and placing a fuse block, but if there is I would like to know. I found out the heat mats for the battery and oil filter were fed from this circuit last year, on a Generac generator when one shorted and blew the fuses and started the generator inadvertently. So I don't see a direct issue with this install. Any more insight is welcomed.

 

[RLyons]

Do you have this shedding setup in the ats?
http://i855.photobucket.com/albums/ab118/BLACK4TRUCK/GENERACLOADSHEDING.png

 

[FREEBALL]

Do you have this shedding setup in the ats?
http://i855.photobucket.com/albums/ab118/BLACK4TRUCK/GENERACLOADSHEDING.png

yes however I want to disconnect the shorelines completely from the generator

 

[FREEBALL]

I did see that there is a contactor that may be available by removing the manual switch handle but Im not sure why I cant just parallel off of the line side of the n1n2 fuses used for sensing. I mean if the sensing 240v circuit is adequate to feed the heating accessories why wouldn't they be ok to feed a coil of a contactor

 

[kwired]

I did see that there is a contactor that may be available by removing the manual switch handle but Im not sure why I cant just parallel off of the line side of the n1n2 fuses used for sensing. I mean if the sensing 240v circuit is adequate to feed the heating accessories why wouldn't they be ok to feed a coil of a contactor

But as mentioned if there is utility power but transfer back to utility has not occurred yet, or even just the right 120 volt leg only which then the ATS likely does not transfer back to normal power, you will send control voltage to your load shed relays/contactors and they will pull in and add load you intended to shed to the generator. Best situation is to somehow monitor the status of the transfer switch. If there is continous power to the standby transfer coil when in standby mode it would be simple to just extend the leads that supply that coil to your equipment or a control relay, but I don't believe all transfer switches necessarily provide continuous power to the transfer coils - so you need to verify what you do have if attempting something like that.

 

[iwire]

If there is continous power to the standby transfer coil when in standby mode it would be simple to just extend the leads that supply that coil to your equipment or a control relay, but I don't believe all transfer switches necessarily provide continuous power to the transfer coils - so you need to verify what you do have if attempting something like that.

I have not seen a transfer switch that supplied continuos power to the operating coils, they may exist but not common.

On the other hand I have never worked with a transfer switch that did not have contacts that allowed me to monitor the position of the transfer switch.

Many of our customers with generators monitor three conditions. 'Generator running', 'Generator failure' and 'transfer switch position'.

 

[kwired]

I have not seen a transfer switch that supplied continuos power to the operating coils, they may exist but not common.

On the other hand I have never worked with a transfer switch that did not have contacts that allowed me to monitor the position of the transfer switch.

Many of our customers with generators monitor three conditions. 'Generator running', 'Generator failure' and 'transfer switch position'.

I don't have a lot of experience with these transfer switches - especially on the troubleshooting side of things - but was pretty certain most I've been around did not send a continuous signal to the transfer coil(s), and likely do use aux switches to tell the transfer logic equipment what position the switch is in.

Most ATS I have been around were residential grade units. Most of my farm customers use manual transfer switches and portable generators, portables in some cases may be larger capacity and run off a tractor PTO - but still is no ATS.

 

[Radioman91]

I installed a generac 22kw and ATS w/ load shedding in a commercial setting. I want to now further shed some load without the load shedding modules. I am using 120 v contactors to shed some load but the panel Im designating the generator panel has 9 shorelines for ambulances. I would like to run from the line side of the sensing fuses on the ATS, a 120v circuit, fuse it at 2 amps in the ATS, to hold a set of contactors that would feed the shorelines from the panel. The panel is 110 ft away from ATS. So when the power drops out, the generator comes on the shorelines will not be powered. Does this sound viable and does anyone else have a better idea. I thought of using sort of a manual shunt that when the power goes out the shorelines would need to be reset, but there may not be personell on site at that time to manually reset.

Thanx again for any insight.

Use the following GENERAC part.

Aux. Transfer Switch Contact Kit Part # 005621-0

You will have to move the 9 "Shorelines" to a sub-panel fed by a contactor controlled by this aux contact. This will provide a simple and automatic disconnect of the shoreline circuits whenever the utility power fails and the transfer switch connects to generator power.

This part number is compatible with GENERAC 100, 150,& 200 amp single phase transfer switches ONLY.

 

[FREEBALL]

Thankyou for the replies, I have since wired off of the 240v sensing circuit to a 240v dp contactor from there I ran 120v contactors for thhe remainder of shorelines, coil fed with power from the generator panel, so not to overload the sensing circuit. It has worked fine thanx again.

 

[ATSman]

Thankyou for the replies, I have since wired off of the 240v sensing circuit to a 240v dp contactor from there I ran 120v contactors for thhe remainder of shorelines, coil fed with power from the generator panel, so not to overload the sensing circuit. It has worked fine thanx again.

If you say it works then fine. However, I cannot see how it would work properly as Kwired, iwire and myself have stated that when the ATS is in emergency position and utility comes back, the load shed circuits get reset before the timer on the ATS sends it back to utility (gen becomes oveloaded.)
If the ATS transfers back to utility with no delay once utility comes back then it will work but that is a bad design when there is no return delay time.

 

[FREEBALL]

Thanx again, yes I took into consideration of that. The generator only supplies 50% of calculated load at any given time. The only large load is the AC for a server room. When power switches back to utility the AC load will not be involved due to load shed control, decreasing load even more. So with that being said, yes there are 9 shorelines/1 aux shoreline normally not used, connected but only half of those theoreticaly will be used at any given time being that half of fleet will be out of station at satellite stations which gives approx. an additional 5000 watts of of spare power until utility transfer. Any thoughts are welcomed. I could, if need be place a timer cube in the circuit to delay the shorelines which was thought about but with the load % being as small as it is the short time between transfer shouldn't be an issue.