OPERATION AND MAINTENANCE MANUAL
SINGLE PHASE MCRII SERIES BATTERY CHARGER
Rev: 1.15
22/08/2018
Doc: MAN-1P_MCRII
Page 10 of 36
Australian Technology
–
Australian Made
64 Bushland Ridge, Bibra Lake, WA 6163 P: +61 8 9434 6621 F: + 61 8 9434 6623
4.0
CIRCUIT DESCRIPTION
See Charger Schematic drawing in the Appendix
The AC input voltage is applied to the power transformer (T1) primary winding via the
input EMI filter and the input Circuit Breaker CB1. Transformer (T1) galvanically
isolates the AC mains input from the DC output and converts the mains voltage into
secondary voltage of the required levels for the power bridge (BR1).
The half-controlled thyristor bridge operates in a phase control scheme to rectify and
regulate the output power. The unfiltered DC voltage produced by the bridge is fed to
the Inductor/Capacitor filter network (L1, C1) for smoothing. The filter reduces the
ripple content of the output DC to a very low level. The charger current is sensed by
the current shunt. A separate shunt senses the battery current for the purpose of
battery current limiting and display.
4.1
CONTROL AND MONITOR CIRCUITS
The control circuit monitors the output voltage and current and compares them with
set values; the thyristor conduction angle is then adjusted to ensure that the output
voltage and current are in accordance with the preset levels.
The control circuit is contained on three electronic circuit boards. The Interface Board
(A2) communicates with the MCRII Microcontroller Board (A3) via a 34-way ribbon
cable and carries out the following functions:
1.
Buffers and filters and scales the incoming voltage, current and temperature
signals.
2.
Buffers and level translate the control output to the SCR Firing Board (A1).
The Interface Board also contains an isolated +/-12V power supply. This power
supply is in turn supplied from two sources, a step-down control transformer with 18V
secondary and the battery. This ensures that the control circuit is powered even
when either the mains or the battery is absent. The control power is distributed via
the 34-way ribbon cable to the Microcontroller board.
The Microcontroller Board monitors the battery and charger parameters and
generates alarm signals which are used to drive the alarm LEDs and relays on the
relay board A4, if installed. A common alarm relay situated on the Interface Board
