XW system: Inverter is 6kW, generator 18kW - how to wire?

aj164

Will a Xantrex XW6048 (6kW) inverter auto-start a generator when it needs backup muscle? Say I put 10kW of load on the inverter. Is there any way to wire this up so that the 18kW generator comes on automatically to handle the excess load?

The wiring diagram: It seems, for automatic operation, the generator must go through the AC1 or AC2 inputs (through the inverter's transfer switch). According to the wiring diagrams, this limits me to 60 Amps (the breaker required on the XW), or 14.4kW.

Is there another way to wire this to do what I need?

-AJ

mike95490

Re: XW system: Inverter is 6kW, generator 18kW - how to wire?

Most generators will take at least 30 seconds to crank up, come up to speed and become stable, before they can assist a load.

The internals in the XW can only handle so much power, so I think you will eventually hit the 60A limit.

RCinFLA

Re: XW system: Inverter is 6kW, generator 18kW - how to wire?

XW will suppliment the generator but for a 10 kW load you would have to have the generator running on line with the inverter before applying the load. If you can get an indicator that the load is needed (like an air conditioner thermostat signal), the generator could be pretriggered to be on line before load is applied.

With the extra auto start module you can set up the XW to fire up the generator when ACout load exceeds a preset level but the load must be within the 6kW max power and support the load until the generator stabilizes, XW sync's with it, and finally engages power from the generator.

The 60 amp AC2 input applies (max 14 kW).

aj164

Re: XW system: Inverter is 6kW, generator 18kW - how to wire?

Does it make any sense to use the external auto transfer switch (came with the inverter) to bypass the XW system and power the house directly?

I would wire the external transfer switch such that when the generator is running, the house main panel is connected directly to the generator. When the generator is not running, the house main is connected to the inverter output.

Generator output will also go to AC1 input on the inverter to charge the batteries.

The advantage of this arrangement would be that we have the full 18kW available from the generator to the house (less what the inverter/charger draws to charge batteries).

The disadvantage in wiring this way is that we lose the ability of the XW to auto-start the generator over a certain maximum load setpoint. Sure, it could start the generator, but then the transfer switch would cut the inverter output out of the circuit, and the XW would see zero load and shut the generator down.

Is there a good reason not to use an external transfer switch?

RCinFLA

Re: XW system: Inverter is 6kW, generator 18kW - how to wire?

You will get 14 kW pass through capability with the 60 amp pass through capability of the XW.

I personally would not use the external transfer switch as you lose too many of the XW features with pass through.

Since you say you would tie gen to AC1 this makes me thing you are off grid. Tieing to AC1 or AC2 will not make any difference in off grid setup. Only difference is XW will select AC1 if available.

You will lose ability to load shave and since your loads and XW are independent the only way to ensure the generator is not overloaded is to backoff on XW max AC input current limit setting.

How are you going to get the transfer switch to activate? My point here is if you have a method to activate transfer switch then you have ability to start generator before load is applied. Most transfer switches (which I assume came with gen not XW) activate based on grid voltage loss.