Conext SW 4024 & 3 phase from generator

Caribbean Solar

Hello Amigos

I'm having problems with my Schneider Conext SW 4024 when the 3 phase generator kicks in in the event of a grid power out, it gets the red warning light flashing (warning 92: connected to a 3 phase AC source) and if there is a lot of load in the inverter it will drop the energy from the generator and start inverting using the energy from the batteries, it keeps going back and forward from batteries to AC. When input is power from the generator it reads line 2 input as 0, so only input from line 1 is good.

Where I live there are 7 houses that share a generator (3 phase) and it's timer controlled, comes in only 3 hours during the day (12-3)(if there is no grid) and when ever the grid power goes off at night.

I have the charger in my inverter set off as I charge my batteries with solar, will this have something to do with it?

My house is connected to the grid but the service is not very reliable and expensive, during the day I'm mostly with solar power and the rest of the day/night connected to the grid and with the generator in case the grid goes off.

Thanks for your help.

Ricardo

inetdog

Re: Conext SW 4024 & 3 phase from generator

Your situation where the normal power is single phase (center tapped to give 120/240?) and the alternate power source is three phase is certainly unusual.
When on alternate power your line-to-line voltage will be 208V instead of 240V, which might also cause problems with some motors and other equipment. Heating appliances should just not heat as fast.
If your wiring uses any three wire circuits with a common neutral along with two hot leads from opposite sides of the 240, then the incidental heating in your wiring will be greater than it was when operating as designed off 120/240.
The only sure way I know of to hide the situation from your inverter would be to use an isolation transformer between the inverter and the utility. This would work OK for a grid tie inverter, with the transformer only needing to carry the PV ouput current.
But with a hybrid inverter with its built in transfer switch that will not work.
If you get a large enough transformer to carry your full house load you could connect its primary from L1 to L2 incoming from the utility (no neutral connection) and the connect the secondary, with a center tap to be used as the neutral, connected to your house wiring including your inverter.
When the feed switches to generator with this setup, however, your 120v loads will see about 104 volts instead.
You have a tough problem.

Caribbean Solar

Re: Conext SW 4024 & 3 phase from generator

Thanks a lot for your help Inetdog.

Regards

mike95490

Re: Conext SW 4024 & 3 phase from generator

You may also have trouble with the frequency stability of the generator, if other loads are impacting it's frequency, or if the voltage/frequency window of the inverter is set too tight.

Caribbean Solar

Re: Conext SW 4024 & 3 phase from generator

Thanks, I did check the frequency and it was 62 but did not look at the voltage, will do so next time the generator is on.

Regards

Caribbean Solar

Re: Conext SW 4024 & 3 phase from generator

I did check the voltage range in the inverter and is from 95v to 135V, the Fq is from 55 to 65. How can my 220V a/c work fine with the generator power but the inverter does not?

The connection for the grid and the generator come into my house as one, I mean they are done outside in a common panel for the 7 houses that share the generator, so the 2 hot wires that come into my house are the same for the generator or the grid, only one comes in at the time of course, so I don't understand why everything on 220v works fine when the generator is on but the inverter sees L2 as 0v?

Any new ideas?

Thanks a lot for your help.

Regards

inetdog

Re: Conext SW 4024 & 3 phase from generator

Caribbean Solar wrote: »

I did check the voltage range in the inverter and is from 95v to 135V, the Fq is from 55 to 65. How can my 220V a/c work fine with the generator power but the inverter does not?

The connection for the grid and the generator come into my house as one, I mean they are done outside in a common panel for the 7 houses that share the generator, so the 2 hot wires that come into my house are the same for the generator or the grid, only one comes in at the time of course, so I don't understand why everything on 220v works fine when the generator is on but the inverter sees L2 as 0v?

Any new ideas?

Thanks a lot for your help.

Regards

The inverter looks at the voltage with respect to ground on each of the two lines, not just at the difference between the two lines, even though it may not use the neutral conductor at all to transmit or receive power.
It is possible that when the generator is on you really have a single ended 220V to ground on one wire and the other wire is grounded.
Or it may be that the voltage to ground on both wires is 220V and because of a phase difference the voltage between the two wires is also 220V.
Both situations are equivalent to a load which is connected directly from L1 to L2. But the inverter has been programmed to expect a certain relationship in the line to ground voltages, and that requirement is apparently not being met.
Again, if the programming of the inverter cannot be changed, you will have to use a transformer between the inverter and the grid connections.

Wulfman

I disagree with the above statement. A SW4024 does not reference anything in the input side to ground or the neutral. it looks at the L1 and L2 inputs for 240v AC. A 3 phase genset should make no difference as his power should be coming from 2 legs of the 3 phase and a neutral just like his Grid power. if the genset has such a wide voltage swing that's more than likely the issue right there. If his inverter is seeing 0V on L2 something is miswired to his house or inverter.

Ethan Brush

Wulfman wrote: »

I disagree with the above statement. A SW4024 does not reference anything in the input side to ground or the neutral. it looks at the L1 and L2 inputs for 240v AC. A 3 phase genset should make no difference as his power should be coming from 2 legs of the 3 phase and a neutral just like his Grid power. if the genset has such a wide voltage swing that's more than likely the issue right there. If his inverter is seeing 0V on L2 something is miswired to his house or inverter.

Are you sure it doesnt get a voltage ground reference somewhere, perhaps through the EGC run with the line conductors? If that inverter is saying that it sees "0V on L2" then either that is poor wording in the programming or means that it has a ground reference. Also the OP's statement that it was giving a warning about 3 phase power source also implies that it has a ground reference as there would be no way to tell if the source was three phase without a ground reference so that the phase angle between the two phases could be detected.

inetdog

Any current design grid tie inverter must monitor the voltages between both hot wires and a ground or neutral to satisfy UL listing requirements. Older designs may not be required to do this, but may do it anyway.
If there is actually no firmly wired ground reference, then the GTI could be seeing 240V on L1 and 0V on L2 because its "ground" reference is floating at the L2 voltage.