4. fuse still blows, check the diodes in the card
Check oscillator printed circuit card AC2.
Replace fuse F2. Turn on-off switch off.
1. Put a piece of paper (insulator) between the
contacts of relay DK so that when the relay is
energized, the contacts will be insulated and not.
make contact. If the relay is a totally enclosed
type, remove the heavy wire from one side of the
relay contact to open the main circuit.
2. Turn on the on-off switch DCS. The unit should
be energized except for the power stage.
3. Check the control voltage at terminals 1 and 2 on
the over and under protection card AC3. This
voltage should measure approximately 26 volts
with a d-c input float voltage of 2.17 volts per cell
(lead acid), 1.4 volts per cell (nickel cadmium).
4. Check the output of the oscillator at the output
terminals of the oscillator transformer OT. The a-
c output voltage at terminals 4 and 5, and 5 and
6 should be approximately 4 volts. If no voltage is
measured at these points, turn the on-off switch
off and remove the wires from terminals 4 and 6
of the oscillator transformer OT. Turn the inverter
on and measure the voltage again as above. If
no voltage is measured, the oscillator card
should be replaced. Note, turn the on-off switch
off before reconnecting the oscillator leads.
Check over and under voltage protection
printed circuit card. The main fuse may blow due
to a defective timing circuit in the over and under
voltage card AC3. The timing sequence is as
follows: When the on-off switch (DCS) is turned
on, the oscillator panel AC2 is energized
immediately. Card AC3 is also energized and its
timing circuit begins timing. After a two second
delay, a pilot relay is energized and its contacts
close connecting terminals 3 and 5. These
terminals in turn apply voltage to DK. DK
operates to energize the power stage. The time
delay allows the oscillator time to start so that the
gates of the SCRs are properly energized when
the power circuit is connected.
The time delay can be manually checked by
disconnecting the wire from terminal 5 of AC3.
Turn the on-off switch on. This will energize the
oscillator and the gates to the SCRs should be
properly firing. Connect a jumper wire one end to
the disconnected wire from terminal 5, the other
end of the jumper wire to touch firmly to terminal
5. The contactor should energize immediately
and the inverter should operate.
If the inverter starts and runs when manually
started (per I. D. 1.), turn the on-off switch off
and reconnect the wire to terminal 5.
Turn the on-off switch on. If the contactor pulls in
immediately with no time delay and the fuse
blows, the timing circuit is defective. Replace the
over and under voltage protection card AC3.
l. E. Check Resonating Capacitor C3 as in step I. A. 4.
Fuses good no output volts.
A. Contactor does not pull in.
terminals 1 and 2 on Main Terminal Board.
2. The over or under voltage setting may be outside
of the limits of the input voltage. See adjustment
3. If the input voltage is proper for the unit and the
main contactor does not pull in, the contactor can
be energized by jumpering terminals 3 and 5 on
the over and under voltage card AC3. Note, the
on-off switch must be turned on before terminals
3 and 5 are jumpered. See ID. If the inverter
starts and runs, check the pilot relay on the card
or replace the card AC3.
Contactor pulls in but output is 0 or low.
1. If the inverter starts and runs but the output
voltage is low, capacitors C3 may be open or
leaky. Voltage across capacitors should be
approx. 660 volts A.C. Check as per 1. A. 4.
2. Check for broken wires. Voltage checks can be
made from terminals 4 and 5 of the power
transformer PT, through the a-c output terminals.