User Manual – Rev B
FCS Series II
5.3 Power Amplifiers Assembly
The AC power system has three power amplifiers, A3, A4, and A5. In the three-phase mode,
one amplifier is used for each of the three output
are paralleled by the user
Each amplifier obtains its
A signal of 5 vrms drives the
output to full scale. The a
s at any frequency from 45 Hz
to 1200 Hz. To achieve h
ifiers operate in class D mode
(pulse width modulation at 75 kHz).
exploded layout, F
5.3.1 In
s. In the single-phase mode, the three outputs
at the output terminal block, TB3.
input signal from the current limit board.
mplifier generates 0-135 VAC at 44 amp
igh efficiency operation, the power ampl
A power amplifier consists of 5 printed circuit assemblies, plugged together, mounted to a heat
sink in a steel case. LED's on each board indicate operational status of each board. See
put / Output Board
The +300 volt supply is connected to J9-3 and J9-4 of the input/output board. The DC supply is
filtered by large electrolytic capacitors that also provide storage and approximately 10 ms holdup
time. There are outputs of the conditioned 300 VDC to both the front and rear amplifiers and a
third output via a 2 Amp fuse to the auxiliary switching power supply.
A green LED on this board is lit if DC above 50 volts (approximate) is present.
This assembly also includes part of the AC output filtering. The AC output is available on J9-1
and J9-2.
5.3.2 Auxiliary Power Supply
The auxiliary power supply us
ll of the low voltage DC supplies
needed for amplifier operation
e following voltages:
1)
±15 VDC to the contro
2)
+16 VDC to the lower gate drives on the front and rear amplifier boards
All five DC supplies are isolated from one another. LED's on the power supply are lit when each
output is in regulation. If an overload condition causes an output voltage to drop more than
10%, the corresponding LED will extinguish.
5.3.3 Amplifier Boards
es the 300 VDC bus to generate a
. This switching supply delivers th
l board
3)
+16 VDC to the top rear amplifier
4)
+16 VDC to the top front amplifier
5)
+24 VDC to the DC fan.
The power amplifier is a full bridge inverter made of two half bridges joined together. One half
bridge is the rear amplifier board, the other is the front amplifier board. Power MOSFET's are
used as the switching device in each quadrant of the bridge. Status of the gate drive to the
MOSFET's is indicated by LED's on the front and rear boards. Green indicates that the power
FET should be on and yellow off. When the unit is switching normally, both green and yellow
LED's should appear lit.
California Instruments
90
Summary of Contents for FCS Series II
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