Trace Engineering Inverter

[cavejumper]

Hello everyone,

I have a customer with a small diesel generator (about 5KW, 120/240V 1PH) connected to two inverters (one on each phase). The inverters also have AC inputs from the utility and DC connections to a battery bank, with AC outputs to a manual transfer switch to the customer's residence. I have some experience with residential standby generators, but have never seen a system like this before. The inverters are manufactured by Trace Engineering and are the SW series. The generator seems to work fine, its the inverters that I'm having a problem with.

When the HO called me the inverters had not worked for over a year. I determined the batteries had lost their charge (was measuring about 2.4VDC across each 12VDC battery). I disconnected all the batteries (16 total, 8 for each inverter connected in series/parallel for a system voltage of 48VDC), and refilled the electrolyte fluid with distilled water since most were low. I then put each one on a trickle charge until complete, measured voltages (ranged from 11.3 to 12.7VDC), and reconnected them. The inverters turn on now, but I'm not sure everything is working right.

The HO has no working knowledge of the system (her husband is the one that tinkered with it and has passed away), and the manufacturer has not responded to my calls. I'm mainly concerned that the batteries will recharge correctly now, but I'm not sure what I should be looking for to tell me that. I would also like a better understanding of the system in general, although I am learning a lot by reading the owner's manual. Does anyone have experience with these? Any input would be appreciated!

 

[ATSman]

I suggest this post be moved to the PV Forum. The people with grid tie inverter expertise will respond accordingly and give you direction.

 

[electrofelon]

I dont really have any direct answers to your question, so just ignore the following if you dont want to hear my rant It sounds like they have grid power so this is a backup system? If so, I would get rid of it. If she wants back up power, and the existing generator is suitable, keep it, otherwise get a new automatic backup generator. It sounds like the woman doesnt know anything about the system so its going to be nothing but a hassle. I would recommend ditching the batteries or not getting involved. I have lived off grid for 12 years so I have the knowledge, but I dont get involved with any off grid or battery stuff for anyone else anymore - nothing but a hassle.

 

[iwire]

I dont really have any direct answers to your question, so just ignore the following if you dont want to hear my rant It sounds like they have grid power so this is a backup system? If so, I would get rid of it. If she wants back up power, and the existing generator is suitable, keep it, otherwise get a new automatic backup generator. It sounds like the woman doesnt know anything about the system so its going to be nothing but a hassle. I would recommend ditching the batteries or not getting involved. I have lived off grid for 12 years so I have the knowledge, but I dont get involved with any off grid or battery stuff for anyone else anymore - nothing but a hassle.

:thumbsup:

 

[cavejumper]

That's honestly how I feel about it, but I want to make sure then that the existing generator will be suitable for her. As stated before, it's a diesel generator, 120/240VAC, 1PH, about 5KW if I recall correctly. I measured its output voltage and frequency, and the voltage is fine, but the frequency is a little low (about 57 Hz). She can maintain the generator, and I think we can make the size work even though it's on the small side. I would like to know that the output power will be stable enough to operate household equipment like appliances and basic electronics. Do I need to look for anything else in order to make that call?

 

[GoldDigger]

The Trace/Xantrex/Schneider SW series inverter is known as a very versatile hybrid inverter-charger which is built like a brick *outhouse*.
Unfortunately the SW series is also discontinued and has also had a history of software problems.

It can function as a standalone inverter, running off batteries charged by PV or it can work as a grid tie inverter when the PV produces more energy than the batteries can take in. If grid is available and the batteries need charging it can also act as an AC source battery charger.
And finally it can work in conjunction with a generator, including automatically starting the generator when battery power from the inverter cannot handle the AC load on its own, and supplementing the generator when the load is greater than the programmed capacity of the generator.
It includes an internal transfer switch that isolates the SW from the grid when power fails, but a separate input for generator AC allows the inverter to work along with the generator, relaxing the anti-islanding tests. Among other things, the generator support capability can allow an otherwise too small generator to ride through motor starting and other peak load conditions. Without it, the generator may well turn out to be too small.

If the OP wants to remove the SWs, it will require adding a transfer switch and generator control unit at a minimum and there will be no immediate carryover power while the generator starts up.

That said, it appears that the SW(s) are not properly charging the connected batteries. Until that problem is sorted out (by someone familiar with hybrid inverter-charger operation), there is no assurance that they are working properly and it can be expected that the batteries will continue to discharge to the point of failure. In addition, batteries that have been at that voltage for any length of time are likely to have been damaged beyond full recovery.

My advice is that if you cannot find someone with the knowledge to troubleshoot and maintain those discontinued units, they need to be replaced, even if only with a generator system.

 

[ggunn]

If it hasn't worked right for over a year the batteries may be toast.

 

[SolarPro]

That inverter was probably installed prior to 2000. It can probably be fixed. Since there is no longer any manufacturer support (due to the various acquisitions), you'd have to find a legacy service provider. For example:

Mark Snyder Electric

 

[pv_n00b]

I run into these once in a while, the husband was a tinkerer and had a project like this that he liked working on and kept up. He dies and the wife is left with what is basically a high maintenance hobby system that she has no knowledge of. If she has no pressing need for backup power then I would recommend just disconnecting the system and maybe selling the working parts for her. If she has a need for backup power it would probably be better to set her up with a system that does not require constant tinkering to maintain. What was fun for her husband is no help to her. If the generator is in good condition then all you need to add is auto start and an auto transfer switch and she has backup power.

 

[cavejumper]

Thank you all for your input and advice. I'll be going to the customer's house today to check on the batteries, see if they're maintaining their charge, and if not, I'll recommend bypassing the inverters and only using the generator for backup power. Thanks!

 

[GoldDigger]

Thank you all for your input and advice. I'll be going to the customer's house today to check on the batteries, see if they're maintaining their charge, and if not, I'll recommend bypassing the inverters and only using the generator for backup power. Thanks!

Please do not forget that the inverters are in all likelihood currently supplying both the transfer switch and the generator control functions. So getting the inverters out of the circuit will involve more than just "bypassing" them.

 

[SolarPro]

If the system is installed correctly, it will have a bypass switch that completes a circuit that, as the name suggests, completely bypasses the inverters. This design/installation practice allows the inverters to be removed and serviced. If you observe the usual electrical safety practices and document the as-built condition (if you plan to repair and reinstall the inverters), this shouldn't be a particularly difficult O&M operation.

 

[pv_n00b]

If the system is installed correctly, it will have a bypass switch that completes a circuit that, as the name suggests, completely bypasses the inverters. This design/installation practice allows the inverters to be removed and serviced. If you observe the usual electrical safety practices and document the as-built condition (if you plan to repair and reinstall the inverters), this shouldn't be a particularly difficult O&M operation.

I think GoodDigger was referring to the generator control system that some inverters have. If the battery gets low the inverter will start up the generator automatically to supply power and to recharge the batteries during an extended outage. I'm not familiar enough with the older Trace inverters to know if they supplied that functionality but since this is a combination inverter w/storage and generator system there is either an automatic system to start the generator or someone would have to manually start it when the batteries ran down. If the inverter did provide this function then simply bypassing it would be a problem as the generator would not automatically start on loss of the grid.

The inverter might have also been handling the transfer function from grid to backup source.

But, based on the OPs description I would not be surprised to learn that the owner did it all manually.

 

[GoldDigger]

I think GoodDigger was referring to the generator control system that some inverters have. If the battery gets low the inverter will start up the generator automatically to supply power and to recharge the batteries during an extended outage. I'm not familiar enough with the older Trace inverters to know if they supplied that functionality but since this is a combination inverter w/storage and generator system there is either an automatic system to start the generator or someone would have to manually start it when the batteries ran down. If the inverter did provide this function then simply bypassing it would be a problem as the generator would not automatically start on loss of the grid.

The inverter might have also been handling the transfer function from grid to backup source.

But, based on the OPs description I would not be surprised to learn that the owner did it all manually.

If the previous solution, when working, combined the output of the trace inverter and the generator it is almost 100% guaranteed that the grid connection is being made through the internal transfer switches of the two Trace units and they are also being used to autostart the generator when the battery goes low or more current is being demanded than the inverters can supply on a long term basis.

Any other configuration would not be making the best use of the Trace capabilities and I think the "tinkerer" would have gone for that scenario.

 

[Zee]

Any solar panels installed?