Inverters change Direct Current (DC) to Alternating Current (AC).
Stand-Alone inverters can be used to convert DC from a battery to
AC to run electronic equipment, motors, appliances, etc. Synchronous
Inverters can be used to convert the DC output of a photovoltaic
module, a wind generator or a fuel cell to AC power to be sold to
the utility grid. Multifunction inverters perform both functions.
Synchronous Inverters
Synchronous inverters change DC power into AC power to be fed into
the utility grid. A power system with this type of inverter uses
the utility company as a storage battery. When the sun is shining,
your electricity comes from the PV array, via the inverter. If the
PV array is making more power than you are using, the excess is
sold to the utility power company through a second electric meter.
If you use more power than the PV array can supply, the utility
makes up the difference. This type of system makes the most sense
if you have utility power, because there are no batteries to maintain
or replace, but it has a very long payback period and may not be
cost-effective at today's electric rates. Using a multifunction
inverter allows you to sell excess power to the utility, and also
maintain a battery bank for stand-by power in the event of a utility
power failure.
Multi-function Inverters
Trace Engineering Company produces a line of true sine wave inverters
called the SW line, that can operate as Stand-Alone inverters and
as Synchronous inverters at the same time! In a typical installation,
the Trace SW inverter is connected to a battery bank, the utility
power lines, a standby generator and the house load center. When
batteries are in a charged condition, the SW inverter supplies AC
power to the house from the batteries. If the batteries become discharged,
the inverter supplies the house loads from the utility lines, while
charging the batteries. If the batteries become fully charged by
another power source, such as photovoltaic modules or a wind or
hydroelectric generator, excess power may be sold back to the utility.
If utility power fails, the inverter can still operate, supplying
critical loads. If a standby generator is started, it can also supply
power to loads. The inverter will synchronize to the generator and
allow loads to be powered that are too large for either the generator
or inverter to supply alone.
Stand-Alone Inverters
Stand-Alone inverters convert DC power stored in batteries to AC
power that can be used as needed. Selecting an inverter for your
power system based on the maximum load you will be powering, the
maximum surge required, output voltage required, input battery voltage
and optional features needed. High quality stand-alone inverters
are available in sizes from 100 watts, for powering notebook computers
and fax machines from your car, to 8000 watts, for powering an entire
house or small commercial operation. The size of an inverter is
measured by its maximum continuous output in watts. This rating
must be larger than the total wattage of all of the AC loads you
plan to run at one time. The size of the inverter can be minimized
if the number and size of the AC loads is kept under control. Wattage
of most AC loads can be determined from a tag or label on the appliance,
usually located near where the power cord enters, or from the owner's
manual. If the inverter is expected to run induction motors, like
the ones found in automatic washers, dryers, dishwashers and large
power tools, it must be designed to surge, or deliver power many
times its rating for short periods of time while these motors start.
Stand-alone inverters are available with three basic power output
waveforms: square wave, modified square wave (sometimes called modified
sine wave) and pure sine wave. Synchronous Inverters and Utility
companies deliver a pure sine wave.
Square wave inverters have the lowest cost and efficiency and are
not sold in this catalog. The price of the better quality inverters
is low enough to make square wave inverters an unattractive choice.
Trace 700/800series, DR series, U series inverters and Genius inverters
have modified square wave output with harmonic distortion of around
40%. They are an economical choice in power systems where waveform
is not critical. Their high surge capacity allows them to start
large motors while their high efficiency makes them economical with
power when running small loads like a stereo or a small light. They
can power most lighting, televisions, appliances and computers very
well. We do not recommend them for computer systems with laser printers.
Unfortunately, this type of inverter may destroy some low cost rechargeable
tools and flashlights, and their waveform will not allow many laser
printers, copiers, light dimmers and some variable speed tools to
operate. Some audio equipment will have a background buzz that may
be annoying to music connoisseurs.
Sine wave inverters have a slightly higher cost, but they can operate
almost anything that can be operated on utility power. Trace Sinewave
inverters are available in sizes from 2500 watts to 5500 watts,
and a pair of them can be synchronized to deliver up to 11,000 watts.
They are an excellent choice for a 'whole house" inverter.
Exeltech sinewave inverters, available in sizes from 150 watts to
2000 watts, are an excellent choice for power systems running audio
equipment and other electronics that are waveform-sensitive. Larger
Sinewave inverters are available in sizes up to 200,000 watts, that
can run a small village.
Output Voltage
All of our inverters supply standard 120 Volt 60 HZ AC power, such
as one gets from utility companies and fuel-powered generators.
Most of them can be special ordered with other output voltages and
frequencies for use anywhere in the world. Please contact us with
any special requirements that you have.
Interference
The electronic circuitry in inverters may, in some
cases, cause problems with radio and television reception, noise
on telephones and buzz in audio equipment. Sine wave inverters cause
the least amount of interference. Interference can be minimized
by locating the inverter very close to the batteries, twisting
together cables that connect the inverter to the battery and locating
the inverter away from appliances that are susceptible to interference.
All inverters cause interference on AM radio!
