INSTALLATION AND OPERATING INSTRUCTIONS FOR INVERT-A-VOLT MODEL A-51
The -LaMarche Model A-51 Inverter is designed to supply
120 volt AC, 60 cycle, sine wave from a DC battery
system. Since this unit is convection cooled, it is
necessary to mount the inverter in a vertical position so
that the expanded metal case openings are at the top
and bottom with the nameplate right side up. A minimum
of two (2) inches should be clear above and below the
case. The unit should not be mounted in any space less
than 10 times the volume of the case.
The Invert-a-volt can be damaged by high temperatures
and should be mounted in an area that does not exceed
an ambient temperature of 140°F.
Check the nameplate of the Invert-a-volt to make sure
the correct type and number of battery cells is provided
for the DC input to the inverter. Connecting wires from
the inverter to the battery must be as short as possible
and permanently fastened. When connecting the input
cables to the battery make certain the positive lead to the
inverter is connected to the positive terminal of the
battery and a negative lead of the inverter to the negative
terminal of the battery. The output terminals should then
be connected to the AC load. For correct AC and DC
cable size consult table number 2. Make certain the AC
load demand does not exceed the continuous rating of
the inverter. Consult table number 1 for continuous
The inverter is equipped with an on-off switch on the front
of the case. Turning this switch on puts the inverter into
The inverter DC terminal voltage reading should be the
same as the battery voltage and should agree with the
nominal nameplate voltage. The inverter is designed to
operate on a battery within a voltage range of 1.75 to
2.45 volts per cell (lead acid battery) or 1 to 1.55 volts per
cell (nickel cadmium battery).
The AC output load wires should be disconnected or all
AC loads turned off. Turn the inverter on and measure
the AC output voltage.
Reconnect the load wires or turn on the AC loads. Turn
on the inverter to power the load. The voltage drop
should be checked between the inverter and the battery
when the inverter is operating. A very slight voltage drop
will indicates gold installation.
The low voltage protection feature protects the inverter in
the event the DC input voltage is low. The DC contractor
will not operate to power the inverter unless the voltage is
correct. This also protects the batteries from excessive
Should the continuous rating of the Invert-a-volt be
exceeded due to an overload or short circuit, the unit will
go into a current limit mode of operation.
Excessively high DC input voltages may damage the
inverter, therefore, a high voltage protection circuit is
employed to protect the inverter and shut the unit off. If
the DC input is shorted to the AC output of the inverter,
the unit will not be damaged.
A generator or charger should be used to maintain the
inverter batteries. The charging equipment should be
sized so that it will keep the battery charged and carry the
average DC load to the inverter.
The maximum "on charge" voltage of the charging
equipment should be adjusted so that voltage does not
exceed 2.45 volts per cell on lead acid batteries or 1.5
volts per cell on nickel cadmium batteries. If the on
charge voltage exceeds the above values. the inverter
high voltage protective circuitry will automatically turn the
The battery size is an important consideration in
successful inverter operation. The amp hour capacity of
the battery must be large enough so that the voltage will
not drop below 1.75 volts per cell when the inverter is
operating at its full load capacity. If the inverter is to
operate on the battery continuously without charging
equipment, the battery size must be large enough to
carry the inverter load for the length of time required.
Other DC loads on the battery must also be considered
in sizing the battery. The number of battery cells must
agree with the nameplate rating of the inverter, otherwise
the inverter will not operate correctly.