3524 Outback and Generator Do not like each other........YET~

Re: 3524 Outback and Generator Do not like each other........YET~

I am a Trace user so do not have direct experience with Outback. From the specs, I would say the Outbacks' have a narrow phase lock frequency range and very slow tracking to changes in input frequency. This is fine for grid tie and helps them in meeting the grid-tie anti-islanding requirements. This is the primary reason the manual says generator feed capability is not recommended.

Small generators bog down in speed, and therefore output frequency, when load surges happens. The start current on your refrig is much higher then your run current. I would suspect the problem begins shortly after the refrig compressor kicks on putting the generator and Outback out of sync lock.

Inverter-generators have very good frequency control as it is set by quartz crystal timebase but do have a dip in voltage when load surges happen. This should not be a problem for the Outback inverter. You may also have to be careful as inverter-generators in less then 3KW class have balanced output meaning it is not good to ground bond the common (wide blade side) of the output plug. I know some people are doing this but they probably don't realize they might get a nasty shock if they touch the metal case of the generator when they are grounded. Grounding the common can also damage the electronics in the inverter circuit. I have a Yamaha EF3000i feeding into my Trace through an isolation transformer.

Re: 3524 Outback and Generator Do not like each other........YET~

The isolation transformer only allows the inverter-generator to stay floating as a push-pull H-bridge design dictates. It does not stop backwash from Trace inverter.

I am a little surprised you blew the alternator. I would more expect something in the generator's inverter circuit would blow first.

Being 240 AC system, things are a little difference then U.S. You carry no current in the what U.S. calls the common or power grid ground system for 120v loads. The 240 v inverter-generator should work without an isolation transformer on your system as it is floating (or more specifically, center-tapped ground) with respect to ground.

The Trace SW series and Outback FX series operate syncronous and in parallel to the grid. This is just like another power company generator on-line parallel to grid. It must match the phase and voltage of the grid (or generator) source. If inverter is a little higher in output voltage then grid, it pushes out power to grid (or load). If inverter is a little lower in output voltage then grid, it sucks in power from grid to charge the batteries.

So how does it tell when the generator runs out of gas and stops. Answer is they sense the frequency and voltage drop by increased backwash current into the source, in this case the generator. There is a current sense transformer in series with AC input from generator (or grid) and the parallelling relay opens when the backwash current exceeds the Trace/Outback load limit. This means for a moment there is a significant amount of current being forced into the generator from the Trace/Outback inverter.

This sounds bad but the generator should take it for a short time. A generator supplying a high inductance load motor will have backwash current during some portion of the AC cycle due to inductive power factor.

I would be more incline to believe the way the generator stopped caused the problem. Some generator gas engines, as they begin to run out of gas, just start to wobble in speed, back and forth, for quite a while before sputtering down to a stop. If the speed wobble is small enough, the Trace/Outback may not reach its release limit. This could extend the release process and result in longer backwash into the generator, possibly damaging it.

I have worried about this with my Yamaha generator. I have never let it run out of gas while connected to my Trace inverter. I am sure it will happen someday, but to date, I have always disconnected it, refueled and restarted it, then reconnected it to Trace inverter. The Yamaha does seem to "fizzle" almost immediate when the gas tank runs out but I have not had the guts to actual try it while connected to Trace.

Re: 3524 Outback and Generator Do not like each other........YET~

Hi Thanks for your reply, the genset was a Kipor 6700TA with AVR a diesel 4.5kva rated 5 kva max. It had 500 hours use with the Sw , always gave a very stable 230 50 hz output (digital display on genset) I had max AC2 amps set at 18 and max charge rate set at 13, it was always well fueled diesels arnt easy to restart after running out. and I manually started stopped the unit. It was by far the best gen Ive used for stability and ability to charge my batteries efficiently. I cant rule out simply failure on the generator its self. When I started up the generator after seeing the ac 2 light on when it shouldnt have been, the engine laboured heavily read about 200 volts on display normally shoots to 230v . I quickly shut it down disconnected the supply plug, then restarted it again, engine ran ok but no power output. The alternator was hot and the smell of letting smoke out was present. I was hoping that you isolator transformer was acting like a big AC diode . guess not.
I have 1.6 kw of solar up now soon to be 2.4kw and my gen useage has dropped dramatically I have a friend whos trying to source me a 7/8 kva water cooled 1500 rpm unit (very sought after over here for decent money)for the future and I am making do with a not so impressive cheap LPG 6 kva unit as a standby. The Kipor got repaired with a UK made alternator the the engine stopped working a 100 hours later. I still have a little Kipor suitcase 2kva inverter type unit withover 700 hours on it fantasic clean output, so my feelings towards Kipor are a bit mixed. thanks for you help any further suggestions comments welcomed, Nigel