Industry Forums > Wireless Service Providers > OT - Simple Disconnect/Isolation Switch

OT - Simple Disconnect/Isolation Switch

What kind of ATS?

reply to warwick
I think that the only acceptable solution is a Grid-Tie Inverter fed by your PV system. These Inverters can also have provision for a generator input.

They are not cheap or simple but the Power Company will not have it any other way. You will need a permit and a Master Electrician to sign off on the installation or you could face legal penalties.

reply to warwick
Woah deleted... I'm an idiot

reply to warwick
Thanks for the replies.

Nunya: Will get the particulars of the transfer switch tomorrow lord willing - however I imagine it's your average 3 pole break before make switch, the amperage rating should be 600 @ 240vac.

bburley: while I agree, I wasn't the one who initially designed and spec'd the system - If it were my call it would have been done differently. The only thing I can do at this point is to ensure that "fail-safe" mechanisms are in place which would protect human life and prevent property damage.

The grid tie inverters in this scenario are UL 1741 rated for the intended application which means they MUST cease to produce power once it senses the mains is out of sync. (I.e. a power loss or another fault condition) However I'll sleep better at night knowing there is no physical connection in the event the mains is disrupted which is why I'm looking for the switch in question.

To note: there are a few things missing from the diagram above.

Load = Primary Breaker panel.
Alternate AC input amperage: 31.5 @ 240 vac. (Single Phase)
Necessary breakers.

Mains "sensor wire": Should be the wire which measures line frequency and voltage before the transfer switch. This would signal the "isolation switch" to either cut on or off.

reply to warwick
EDIT: Relooked at your diagram, probably not at all what you're looking for! Why is your PV, AC?

hrm,

how about something like the xnatrex units?

like this?

»www.xantrex.com/power-products/b···800.aspx

Then your AC power input is switched by an auto transfer switch??

reply to warwick
I was asking about the ATS because many have auxiliary contacts. You could accomplish what you need with a simple definite purpose contactor.
The contactor would be wired in a N.O. state between the Aux Source and the load. If the budget allows, and the Aux Source current is low enough, I would spring for a solid state contactor.
The coil would be powered off of utility power. However, once utility power is restored, it usually takes the ATS some time to switch back over. That's where the ATS comes into play. If properly equipped, you could loop the utility fed coil power through the ATS N.C. terminal(s) to keep the Aux Source from coming back online until after the generator goes off line.
E.G., the Aux Source only works when utility power is on line and generator is completely off line. Both conditions would have to be met.
Most decent ATS's have auxiliary contacts available.
--
If someone refers to herself / himself as a "guru", they probably aren't.

reply to warwick
Make the load common though the DPDT isolation relay. The coil is connected to the utility/genset line on the ATS output side.

This meets your condition of not having both AC sources connected at the same time, under any circumstance.

It's either one or the other...

reply to nunya
Hmm, thought about that as well. Didn't know those beasts came with aux. contacts. If I'm lucky the logic board will have these contacts in place and maybe I can put the corresponding relay in place.

Really overlooked the fact that the ATS really controls what is what, I.e. the ac could be fine and well however the ATS could still send Gen power to the load (haven't checked the delay).

Will do a more detailed drawing with relays and thingamajigs when I take a look at the transfer switch internals.

Preventing backfeeding* and the destruction of the Generator or PV system is paramount at this point.

Thanks for the help.

reply to John Galt
Thanks John,

However in this case, the Alternate AC source (PV) can work in tandem with the utility side, however the Generator will not play so well.

reply to prairiesky
Right path, different lane.

With the system in question, the only DC present is what the panels convert, everything else is AC.

So its ideally straight from the PV source to the load panel.

reply to warwick
Post the ATS model...

reply to warwick
I'm still trying to figure out what you're doing and why.... Does your PV AC sync with your line power? What's the thinking here?

how about something like this;

»www.apc.com/products/family/?id=371

reply to warwick
If I'm reading this right, I'm surprised there isn't an auto switch on the PV already if it's tied in to the line at all. I thought systems like that that back fed to the power co's lines had to have one in case there was a power issue to begin with. IDK.

I think the guys are right with the ATS having contacts, and you should be able to just add a contactor to make that work the way you want.
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»www.wirelessdatanet.net

reply to John Galt
It appears to be a Thomson TSC-800 model/series.

Rating: 400 Amps @ 480v

Looking through the literature suggest that there is a powered output (can either be mains or gen.) that is dependent on both the source power and the switch position.

(will try to verify with the manufacturer tomorrow.)

If this is true I will simply take the power off this lead and go straight into the contactor.

The TSC-800 is a controller for an ATS. You're probably looking for a number like TS8XX ATS.
What kind of service are we talking about here? Single phase? Three phase?
--
If someone refers to herself / himself as a "guru", they probably aren't.

Sorry, forgot to note . Although the entire assembly appears to be Thomson branded. Will have a look inside the ats tomorrow.

TS853TCJ-400A-480.

Single Phase. 240vac.

It looks like there are outputs available in the ATS controller:

- Transfer to Utility 10A
- Transfer to Generator 10A
- Pre/Post-Transfer to Utility 3A
- Pre/Post-Transfer to Generator 3A
- Load on Utility 3A
- Load on Generator 3A

You could use the "load on utility"...or "transfer to utility" if you needed a bit more heads up (milliseconds).

Using one of these dry contact sets to operate the isolation relay, the genset set could still be running in the cool-down mode and the PV inverter brought back online since the load has returned to utility power.
--
The most powerful weapon in the world is ignorance. Politicians exploit it to achieve almost anything they want.

Thanks for the response Galt.

You are correct - went ahead and programmed/tested the relay output settings via the ATS control panel.

Selected the "Load on Utility" Option. Will run a 120vac coil through it.

The only problem is, because the contacts in question are "dry contacts" I will have to safely find a way to feed 120vac from the utility line before the transfer switch utility input. I'm thinking a small fuse assembly should suffice. Something rated in milliamps.

Also will post pics and a detailed set of setup instructions, also including modifying the transfer switch if necessary to implement one's own microswitch provided the ats does not have one.

(I'ts all simple but hopefully It'll help someone trying to achieve the same effect)

Thanks.