LP Generators

trumpets3u · March 2007

I'm off the grid. I have a Xantrex SW 4024. I have a generator but I want to get a Guardian 7KW to hook up so it will start up on it's own this are sold as back up for on the grid.. I know the SW 4024 will do this. But will it with this one? Will this work or do I need to get the B&S LP generator with the remote start.
Thanks
Brian

dhill · March 2007

Re: LP Generators

I'm not sure how the Xantrex inverter works. I have an Outback and with the mate, it auto starts my gen. My generator was a two wire gen. I had to add a step down transformer to balance the two sides from my gen. Mine was fairly simple. The generator manual showed me where to connect the line to auto-start, and the Outback support helped me with the transformer hook up that and the line from the Mate to the gen for the auto-start. I put a relay between the Mate and the gen also as instructed to do so from some knowledgeable people here. I'm not sure if the Guardian is a 2-wire or 3-wire gen. I looked at those gens before I bought, but I went with a Coleman because it has a Honda engine. You can call the techs at Guardian and they should be able to tell you about the auto connection. You can also have a gen built so that you don't need a transformer, but I don't know if it's worth the effort or how long it takes or if there's more cost involved. I was told I could order my generator that way, but I never checked into it. Good luck

arcandspark · April 2007

Re: LP Generators

trumpets3u: If the generator is a two wire start system meaning the switch you use to start the generator is like a toggle switch that you just flip it to the on position and the generator starts and runs until you flip the switch to the off position, than yes the Trace unit will be able to start the unit OK. But, the relay that you will be using inside the Trace unit can only handle a max current of 5 amps. I strongly suggest you install an extra 24 volt relay and have that relays coil be controlled by the Trace inverter (with a 4 or 5 amp fuse in the circuit). And then have the generators start switch be controlled by that relays contacts. This way if there should be any kind of short or problem with the generators wiring or electrical system it can not send any of its energy back through the relay contacts inside the Trace inverter. If the relay inside the Trace inverter ends up damaged or stops working the complete Trace Inverter will have to be sent back to Trace to have the relay replaced. I use a 24 volt DC coil relay with double pole double throw contacts, from electrical supply store. 24 volts comes from the battery positive terminal through a 4 amp breaker to the relay contacts inside the Trace inverter, to the extra relay coil, back through another 4 amp breaker to the negative terminal. This way the Trace unit controls that extra realy and only that relay. You can install any size extra relay you want so it can handle what ever current load you need. In my case the relay can handle about 10 amps at 12 volts, the 12 volts is the starting voltage from the generator system. If you have a generator that has a three wire system you can make a relay circuit that can start that kind of system also and it can be controlled by the same extra relay that is used in a two wire system, it is a little more complicated and it is not something you can just pick up at a store. Hope this helps you out. I use the relays in the Trace inverter to run a number of other systems that monitor the power system, but you must always protect the inverter relays with a 4 or 5 amp fuse to be safe. Arcandspark

arcandspark · April 2007

Re: LP Generators

One more item of interest, I had to install a separate 60 amp AC relay contactor that would turn "On and Off" the AC Generator Input voltage to the inverter. The problem I was having was when the generator was turned "Off" either by the operator manual switch or by the inverter itself, the inverter would keep watching the AC Generator input voltage and as the generator would slow down as it came to a stop, the inverter would try to follow the generator voltage and frequency and end up going into a Generator Error condition. As the generator spins down the voltage keeps dropping and the frequency keeps dropping causing the error condition. By installing the Generator Input contactor relay, which is also controlled by the same extra relay that starts and stops the generator. When the inverter signals to start the generator the extra relay starts the generator and turns on the AC Gen input contactor. And when the inverter signals to turn the generator off it also turns the AC Gen input contactor relay off, so instantly the AC Gen voltage disappears and the inverter never goes into error trying to follow the generator supply as it spins down. The circuit also controls vent fans so any time the AC Gen contactor turns on, it also turns on vent fans to move air through the battery shed to help reduce battery off gasing and any build up of explosive fumes in the battery shed. The system has been work great for many years. (arcandspark)

RCinFLA · June 2007

Re: LP Generators

The SW4024 will work. It has two relays for this. One of ignition switch and one for starter. If the starter circuit requires more then 5 amps you will need another relay but I think the Guardian's have their own relay for the starter.

I don't believe the Guardian's can wire the output winding in parallel, meaning you will be loading only half side on the output. This limits you output to slightly more then half the generator rating.

For this capability look for generator that has a 120/240v switch on their control panel. This means they can put out full rating power to 120 vac. Think of this as a transformer with two 120 vac output windings. Hook them in series and neutral is center connection so you have 240 vac, and two 120 vac (out of phase) to either side of the center neutral. Hook the two winding in parallel and get full output at 120 vac.

mike95490 · June 2007

Re: LP Generators

arcandspark wrote:

The problem I was having was when the generator was turned "Off" either by the operator manual switch or by the inverter itself, the inverter would keep watching the AC Generator input voltage and as the generator would slow down as it came to a stop, the inverter would try to follow the generator voltage and frequency and end up going into a Generator Error condition. As the generator spins down the voltage keeps dropping and the frequency keeps dropping causing the error condition.

How do you handle a "cool down" period for the generators windings. Most of the ones I've seen, say to disconnect the electrical load for a couple minutes, to let the unit run unloaded, letting the fans blow the residual heat out, otherwise, I've understood, you risk melting the windings by just shutting the motor off. The contactor relay only gives a second or 4 of no load, or is the signal to shutdown programmable ?

System2 · June 2007

Re: LP Generators

I do not believe you would risk melting the windings by just shutting off the generator. With the gen running, the windings can be hot, depending on load, however when the gen is shut off, all generation of both electricity and heat cease, so unless there was an application of heat from an external source, the windings would begin to cool at that point in time, not continue to heat.

Mangas · June 2007

Re: LP Generators

When trying to figure out what to buy myself, GENERAC has new series of 1,800 RPM LP units out with the new advanced H 100 Panel control Panel. It's laptop compatible/programmable/screen diagnostic. I have a 15 KW 60 HZ 120/240VAC standby unit, Model 6692110100, Type SG015 which is not only crammed with features but with the sound accenuated cover it's barely audible. It has its own internal battery charger.

One thing to keep in mind when sizing your LP power unit is your altitude will affect the KW power rating. In my case I think they mentioned that at 5,100 feet my rating is probably nearer 13KW and not 15KW. Since we would only use it for emergency battery charging this may not be as important as someone using it for direct source power. Something to keep in mind if you're in the mountains.

I was told these 1,800 RPM units last longer and are more durable than the higher RPM models.

LP Generators

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