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If the input A.C. power is interrupted, the external battery feeds the load instantane-
ously through the Schottky Diode D2 (D2 will by-pass the resistors R1 & R2). Voltage
available to the load will be approximately 0.4V lower than the battery voltage due to
forward voltage drop across D2.
When the input A.C. power returns, the battery will be isolated and the load current
will once again be supplied by the power supply. The discharged battery will re-
charge through R1 & R2.
NOTE:
The value of charge limiting resistors is based on a typical 100AH deep
cycle marine battery. If a different type of battery is used, the value of the resistor
should be adjusted to meet associated charging requirements.
OUTPUT VOLTAGE ADJUSTMENT
NOTE : The voltages indicated are at no load and are measured at any of the module
output pads under S5 and S6 or at the DC bus before the Schottky Diode D1.
Parallel Operation Under Forced Current Share Control
The output voltage of each module measured at the module output pads under
S-5 and S-6 (See Fig.1) is factory pre-set at 28 V. A precision multi turn potenti-
ometer VR1 is provided for fine adjustment of the output voltage of the module ( The
adjustment range is 26.8 V to 28.5 V ).
For the forced current share control to work properly, it is important that the output
voltage of each module connected in parallel is exactly the same. When 2 or more
modules are operating in parallel under forced current share control and if the output
voltage of any module is below 28 V, it's current share control circuitry will not func-
tion properly and it's LED will start flashing. The LEDs of the other modules which are
putting out 28 V will remain continuously lighted and the output voltage of the com-
mon DC bus (before the Schottky Diode D1) will be 28 V.
If the output voltage of any module is higher than 28 V, it's LED will remain continu-
ously lighted but the LEDs of all the other modules will flash randomly. The output
voltage of the common DC bus (before the Schottky Diodes D1) will read the higher
voltage of this module.
Adjusting the output voltage of the modules at no load
NOTE : The output voltage is adjusted by multi turn potentiometer VR1 ( Fig.1). As the
adjustment is very fine, multiple turns will be required even for small voltage change.
Turn clockwise for decreasing and anti clockwise for increasing . The adjustment range
is 26.8 V to 28.5 V
As explained under OPERATION OF BATTERY BACK UP on page 7, although the
output voltage at the module terminals S5 and S6 ( Fig.1) or at the common DC bus
(before the Schottky Diode D1) is tightly regulated at the preset value of 28 V +/-
1%, the voltage at the output terminals Load + and Load - will vary between 27.8 V
at no load to 27.45 V at full load of 50 A due to the forward voltage drop of the isolat-
ing Schottky Diode D1 and the drop along the DC bus and wiring.
8.
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