OPERATION
Copyright Trace Engineering Company, Inc.
5916 - 195th Street N.E.
Arlington, WA 98223
Telephone: 360/435-8826
Fax: 360/435-2229
www.traceengineering.com
PS Series Inverter/Charger
Part No. 3597
Rev. D: November 23, 1999
Page
71
GENERATOR SUPPORT/OVERLOAD PROTECTION
This battery charger is very powerful and without limits could overload a generator. When the generator is
running, it has to power both the battery charger and any AC loads connected. If AC charge current
combined with any AC load current exceeds the SET GEN (AC2) AMPS AC setting (default = 30 amps),
the charge rate will be automatically reduced to keep from tripping the generator's output breaker or
causing an overload.
If the amount of amperage demanded by the AC loads is greater than the GEN (AC2) AMPS AC setting,
the inverter's power is able to be added to that of the generator's. The inverter attempts to hold the
current drawn from the generator at the setting of the GEN (AC2) AMPS AC. This allows the generator to
start larger loads than it could normally and reduces the load on the generator during motor start-ups.
Generator support is also available if AC voltage falls to the SET INPUT LOWER LIMIT VAC. In this
case, the inverter will assist the generator as long as there is power flowing from the generator to the
load. This is typically used when a large AC load is being operated and the generator’s AC output voltage
drops.
For example, if you have a 20 amp generator and the GEN SIZE AMPS AC setting is at 15 amps, the
inverter will start providing additional power from the batteries whenever the load reaches 15 amps or
higher (even though it may not be required). When setting the GEN SIZE AMPS AC value, allow for
headroom but do not set the value too low.
While the inverter is supporting the generator, the BULK or FLOAT LED Indicator will remain on even
though the inverter may not be battery charging. The INVERTER/CHARGER AMPS AC meter will
indicate the support process by displaying “negative ” current flowing from the inverter to the loads. The
INPUT AMPS AC will also drop during this process while the LOAD AMPS AC remains the same.
120 VAC VS. 120/240 VAC GENERATORS
In the US, generators are available with either 120/240 VAC “split phase” or 120 VAC only output. Some
generators can be rewired in the field, or have a switch, for changing from one output to the other. If a
system uses only one inverter, having the generator put out all of its power at 120 VAC is advantageous.
If two inverters are used, having the generator wired for 120/240 VAC output is better.
If you are using one inverter and can not rewire your generator for 120 VAC, or have a combination of
120 and 240 VAC loads which need to be operated, you may need to include a balancing transformer to
allow full use of the generator output at 120 VAC. This allows the battery charger to use power from both
“halves” of the generator, instead of only half of it. Trace Engineering offers a balancing transformer (Part
Number T-240) for this purpose. See the OTHER PRODUCTS section on page 129 or contact your
inverter supplier for more information.
If your generator can be wired for 120 VAC output and you are using only one inverter, 240 VAC loads
can be operated from the system by using a transformer in a step-up configuration. This is common for
deep well submersible well pumps. If the step-up is done on the pump side of the pressure switch or
manual switch for the pump (run 120 VAC through the switch then step it up to 240 VAC), the transformer
will not interfere with using the search mode or increase idle current draw by the inverter when the pump
is off.
When two PS Series Inverter/Chargers (AE configured) are operating in a “stacked” configuration
(120/240 VAC); each inverter operates as a separate inverter. One inverter can be battery charging with
the excess power from one half of the generator, while the other inverter is supporting the generator by
operating in parallel to support a heavy 120 VAC load on that half of the system. This allows greater
utilization of limited system capacity and is very useful when starting large 120 VAC loads such as water
pumps or compressors.
Two 120 VAC/60 HZ inverters can be used to provide 240 VAC. This provides both 120 and 240 VAC
since a center “neutral” is provided between the two inverters. If a 240 VAC only AC source is connected
to the AC input terminals of the inverter without this center neutral, unacceptable operation will result. To
allow connection of a 240 VAC only source, a small (500 VA) autotransformer must be connected across
the 240 VAC input and to the AC neutral terminals of the inverters. This will allow the inverter to operate
properly. No transformer is required on the AC output side - the 240 VAC can be taken directly from the
two AC hot output terminals (one from each inverter).
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