Inverter
Richard Perez
The Trace sine wave inverters are the most versatile and robust that we've tested. They offer high power, high efficiency, and interface easily with power sources and loads. Here's the results of a year long test on Trace's smallest sine wave inverter, the 12 Volt to 117 vac SW2512.
Shipping Container and Documentation
The Trace SW2512 inverter arrived in fine shape via UPS shipping and a six mile bumpy ride in the back of a 4WD pickup truck. The carton and its foam containment allow shipping virtually anywhere without damage. Which is good because the shipping weight of this inverter is 96 pounds (44 kg).
The documentation supplied is outstanding. Which is also a good thing because the days when the only control on an inverter was an "on/off" switch are over. The 90+ page owner's manual covers everything from setup to operation. It is generic and covers all Trace sine wave inverters, not just the SW2512, possible since all the SW series inverters use the same microprocessor control. If you know how to program any Trace sine wave, then you know how to program them all.
SW2512 Specifications
This is a big inverter—2,500 watts output continuous at 117 vac. Input is 12 VDC nominal, but the unit functions from 11.8 to 16.5 VDC. It is also big physically—15 inches (38 cm) high, by 22.5 inches (57 cm) wide, by 9 inches (40 cm) deep.
The SW2512 functions both as an inverter and a battery charger capable of delivering 150 Amperes DC. The charger is equipped with the latest three stage recharge technique to fully recharge lead acid cells without stressing them out. The charger is programmable so it will not overload small 120 vac sources like low power generators.
The SW2512 will also interface with the utility grid to sell your excess renewable energy. This is revolutionary! Those who are grid connected can efficiently contribute their excess solar, wind, or hydro energy back to the gird and also recharge their battery from the grid when the RE sources are not up to consumption.
The list of things which this inverter will do is too long to go into here. It is unlikely that a single system will ever use all these functions, but it's nice to know that whatever you may need is already built-in. For example, the Trace SW2512 can start your 120 vac engine/generator, automatically recharge the battery, and then shut the generator off. And, if your RE sources are going strong and the battery is fully recharged—no problem, the Trace will automatically divert excess power into a 120 vac load such as a water or space heater. These are just a sample of the power built into the microprocessor in the Trace SW inverters. The Trace SW2512 we tested used the latest rev. 4 software. Yes, inverters now come with software built in. This allows considerable fine tuning of operation without rebuilding the inverter's hardware. If you are a Trace SW series owner using an older inverter with the older software, then call Trace, or your installing dealer, and see about a software upgrade.
The SW2512 inverter's output is a stepped sine wave with between 34 and 52 steps for each alternating current cycle (see photo). Total harmonic distortion (THD) of the output power is rated at 3 to 5%. This means that the SW2512 makes electric power which is, on average, far purer than the utility grid can deliver. The SW2512's sine wave is clean enough to operate virtually any appliance without the problems associated with the older, modified sine wave inverters. Perhaps a word on the difference between modified and sine wave power is in order.
The reason to use a sine wave inverter is simple—sine wave electricity is what every 117 vac appliance was designed to consume. The mod sine wave inverters will power many appliances, but they certainly won't power them all. This list of mod sine incompatible appliances is wide and long—everything from rechargers for cordless drills to laser printers. Even appliances which digest mod sine power will work better if fed pure sine wave power. Our 120 vac well pump pumps about 30% more water per minute with sine wave electricity over being fed mod sine power. Most electric motors will run faster and cooler (which means more efficiency and longer motor life) when fed sine wave power. Computer power supplies run quieter and cooler. TV and radio devices run quieter. This is why the purity of the inverter's power production (measured as THD) is so important. Most mod sine wave inverters make power with 25 to 40% THD. Sine wave inverters make power
Above: a photo of the Trace's 117 vac waveform taken from our oscilloscope. Note the stepped nature of the synthesized sine waveform.
with between 1 and 5% THD. The Trace SW2512 makes power that is pure enough to be approved for utility intertie by Pacific Gas & Electric, California's mega-utility and the largest investor owned utility in the world.
Installing the SW2512
We installed the Trace SW2512 on 1 March 1996, and have had it running continuously since then. It is installed in our main system here on Agate Flat. We used 4/0 copper cables to tie it to the battery bus bars. An Ananda "Big Switch" with 400 Ampere Class T fuse to protects the inverter against overcurrent. We gave the SW2512 its own 500 Ampere, 50 mV. shunt for our instrumentation.
Trace SW 2512 INVERTER TEST - 24 February 1997
INPUT DATA OUTPUT DATA
ON THE 12 VDC SIDE ON THE 120 VAC SIDE
Trace SW 2512 INVERTER TEST - 24 February 1997
INPUT DATA OUTPUT DATA
ON THE 12 VDC SIDE ON THE 120 VAC SIDE
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