Product Manual

Operation
900-0198-01-00 Rev A 17
Multiple Inverters
In a stacked system, whenever the master inverter senses acceptable input, it orders all other inverters to
transfer to the AC source. The other inverters do not use their own input readings to transfer. It is
expected that the AC source delivers input (in the appropriate phase) to all inverters.

If a slave inverter does not sense acceptable input, it will not transfer, but also will not invert. The slave will have
no output. It also will display
Phase Loss Error
.
Generator Input
A generator should be sized to provide enough power for all inverters, both for loads and for battery
charging. The generator’s voltage and frequency must match the inverter’s acceptance settings.
It is usually recommended that the generator be sized at twice the wattage of the inverter system. Many
generators may not be able to maintain AC voltage or frequency for long periods of time if they are loaded
more than 80% of rated capacity.
The generator is required to have a stable output before its power is accepted by the inverter. Some
generators with less stable or uneven outputs may not be accepted. The use of the
Generator
input
mode may assist with this problem.
Transfer
The FX inverter uses a transfer relay to alternate between the states of inverting and of accepting an AC
source. Until the relay energizes, the output terminals are electrically isolated from the input. When it
closes, the input and output terminals become electrically common. When the relay changes states, the
physical transfer delay is approximately 25 milliseconds.
CAUTION: Equipment Damage
Current draw in excess of the transfer relay rating can damage the transfer relay. This
damage is not covered by warranty. Use protective devices of appropriate size.
The relay contacts are limited to 30 amps per phase. The continuous loads on that output should never
exceed this number. When connected to an AC source, the FX inverter cannot limit the load current. An
overload condition is possible.
The inverter does not filter or actively condition the AC source. The voltage and power quality received by
the output loads is the same as that of the source. If the voltage or quality do not meet the inverter’s input
requirements, it will disconnect and return to the inverting mode.
NOTES
:

To ensure a smoother transition, it may be advisable to raise the inverter’s lower acceptance limit. The default
setting is 108 Vac. A higher setting will cause the inverter to transfer sooner in the event of a quality problem.

If the AC source meets the inverter’s requirements but is irregular, any fluctuations will be transferred to the
loads. If the loads are sensitive, it may be necessary to improve the quality of the AC source.
If the charging function is turned off, the inverter will transfer power from the source but will not use it to
charge. If the inverting function is turned off, the inverter will transfer (“pass through”) the source power
when connected, but will not invert when the source is removed.