simulate 120/240v 3 wire single phase utility power

Status
Not open for further replies.
T

Taz22

Member
Location
SW/ NH
Good Day All.
Here's my dilemma......

Workshop is off the grid
Building has 120 volt load-center fed from house, powered by typical solar (panels/invert-er/batteries) running some LED lights and general purpose outlets.
Customer is semi-retired and downsized his woodworking business and kept some equipment which requires 120/240 w/neutral.
Recently installed 14KW 120/240v generator through 200amp automatic transfer switch to separate load-center to power equipment.
(((((Installed transfer switch to monitor & control generator from <startup/delay> to <cool-down/shutoff>.)))))

PROBLEM!!!!!!
Automatic transfer switch is in constant emergency position because there is no incoming utility power. Switch requires 3 wire, phase A,B and neutral.

ANSWER??????
Is there a way to use 120 volts from load-center fed from solar to "create" 120-240 volt w/ neutral to simulate incoming utility power, ie:

on-off switch to control a transformer??:blink:
 
I'm not understanding this either. If the owner has equipment that can only be supplied by the generator, he'd have to start it up anyway?
 
I think he is saying that he has an "automatic standby" type generator on an off grid system, thus the generator is always thinking "the power is out"

I am trying to remember how the ones I typically install behave...... Doesnt it have a "manual" or "test" setting where you can operate the on/off manually?

Alternatively, I am sure it wouldnt be hard to give some voltage to the utility voltage sense input and do it that way. If the inverter is MSW, not sure if that would be a problem.
 
The problem is this:
The "normal" power to the shop is 120 only from an inverter at the house.
To run the generator he would turn off the inverter feed and then all of the shop outlets would run off the generator for the duration.
But since the transfer switch control relay wants 240 he cannot power it directly from the inverter.
A separate issue is whether the inverter supports/allows a grounded neutral and whether he would need an ATS that also switches the neutral.

Sent from my XT1585 using Tapatalk
 
sounds like a 240v 1ph ATS that senses issue from both poles to N. or possibly its just two 120v sensors in the ATS. if the latter than perhaps using the same 120vac from solar on each end of the ATS with a common for the "N" wire. the ATS would then see any fault in the 120vac on both sides of the ATS at the exact same time. a "3 wire" ATS could mean 1ph/1pole, could also mean 1ph/2pole, i suspect the latter, but cannot speculate if the ATS is sensing 240 or 120 to trip.

the big Q is, what ATS switch is it exactly?
 
GoldDigger said:
The problem is this:
The "normal" power to the shop is 120 only from an inverter at the house.
To run the generator he would turn off the inverter feed and then all of the shop outlets would run off the generator for the duration.
But since the transfer switch control relay wants 240 he cannot power it directly from the inverter.
A separate issue is whether the inverter supports/allows a grounded neutral and whether he would need an ATS that also switches the neutral.
Click to expand...
It would help if he just provided the make and model number of the ATS, i.e. if the manufacturer provides online documentation.

Also, if power from inverter is used to keep generator from running, what's going to happen when it gets dark? Does he have an off-grid system with battery backup?
 
GoldDigger said:
The problem is this:
The "normal" power to the shop is 120 only from an inverter at the house.
To run the generator he would turn off the inverter feed and then all of the shop outlets would run off the generator for the duration.
But since the transfer switch control relay wants 240 he cannot power it directly from the inverter.
A separate issue is whether the inverter supports/allows a grounded neutral and whether he would need an ATS that also switches the neutral.

Sent from my XT1585 using Tapatalk
Click to expand...

Maybe, but that doesnt seem to make a lot of sense. That means he would have to go inside to turn the inverter off to make the generator come on. I would assume he just wants to be able to turn on the generator (and leave the inverter on) to run larger tools that are too big for his inverter and batteries.

Most medium to high end off grid inverters have an integral transfer switch and charger so when the generator comes on, that batteries charge and local loads are run off the gen. Not sure if thats what he has. If so, he doesnt really even need the transfer component of the ATS, all he needs is the start logic.
 
My apologies as I'm new to this forum

My apologies as I'm new to this forum

To clarify:
Kohler 14kw standby w/ RDT 200 xfer.
Workshop has a <120 volt only> panel fed from house, it powers a few outlets and some lights for small projects homeowner may be doing.
Generator ONLY supplies panel to operate his 240 volt equipment.
The generator has manual start at unit and capability of remote 2 wire start.
Cons of manual start is possibility of no warm up or cool down delays as the "brains" are in control board of xfer switch.
The decision to have xfer switch is multiple reasons- equipment still on when shutting down OR turning on generator, not letting generator cycle down (cool) before shutting off OR ramping up upon starting prior to load being applied. The other positive is if/when they get hooked up to the grid, it's all set to back-feed shop and house.
I understand typical off-grid would utilize 2 wire remote start but the thinking is xfer would protect genr8r against an "oopsy".
I thought about trying a 120 volt run from "solar panel" tapping to both sides of a DPDT toggle switch but believe control board monitors for both 120 volt legs AND 240 volt across phases. I did try a travel xformer (US 120v to Europe 220v) but since there is no neutral it stayed in gen mode.

If there is a transformer that has 120 volt primary and 120-120/240 secondary, that will solve my problem. Thanks for all your input:)
 
Taz22 said:
Cons of manual start is possibility of no warm up or cool down delays as the "brains" are in control board of xfer switch.
The decision to have xfer switch is multiple reasons- equipment still on when shutting down OR turning on generator, not letting generator cycle down (cool) before shutting off OR ramping up upon starting prior to load being applied.
Click to expand...

I dont really think that warm up/cool down is necessary. I am not sure why generators do that. Think about it, it is not standard practice to do that with any other internal combustion engine equipment or vehicle.

If there is a transformer that has 120 volt primary and 120-120/240 secondary, that will solve my problem. Thanks for all your input:)
Click to expand...
Yeah sure that is common (these are kinda big, all you need is a small control transformer, but as an example):

https://www.hubbell-acmeelectric.com/p-127-120208240277-120240
 
electrofelon said:
I dont really think that warm up/cool down is necessary. Think about it, it is not standard practice to do that with any other internal combustion engine equipment or vehicle.
Click to expand...

On the contrary, it is common with both small and large diesel engines, as well as any engine with a supercharger.
It won't die instantly if shut down suddenly from high load, but its lifespan will be reduced.
On large stationary diesels it is even common to keep an external oil pump running for a few minutes after shutdown to provide cooling.

Sent from my XT1585 using Tapatalk
 
Status
Not open for further replies.
Top