PDS20-18/PDS36-10/PDS60-6
7
CIRCUIT DESCRIPTION
POWER UNIT (X68-1970)
Power Control Circuit
Q12 uses the control signals from the control unit
to control the current of the constant
current
circuit consisting of Q 13 and to driv e Q 11. Q 11
supplies the base current to Q1 to Q10.
The collector emitter voltage of Q 1 to Q 10 is
detected and supplied as the Vce voltage to the
secondary voltage detector circuit of the AC unit.
Current Detector Circuit
R46 detects the output current. IC
2/2 amplifier it
as shown in Table 1 and outputs amplifier current to
the control unit. The current is rev ersed by IC1
1/2 and used as the reference current for the slav e
side in the one control parallel operation mode.
Model
Gain
20-18
33 time as high
36-10
33 time as high
60-6
36 time as high
Table 1
Bleeder Circuit
Two bleeder circuit are used : Input bleeder
circuit, and output bleeder circuit.
The input bleeder circuit has a constant
current
circuit consisting of Q17 and Q19. It bleeds current
as show n in Table 2. When the voltage exceeds
value shown in Table 2, Q14 functions and reduces
the bleeder to about half. When the current
exceeds the output current show n in Table 2, the
comparator IC3
1/2 function and turns on Q 16 to
deactivate the bleeder circuit.
The output bleeder circuit has a constant
current
circuit consisting of Q 20. It bleeds current as
show n in Table 3. It is turned on or off by the
bleeder signal output by the control unit.
Model
Input side
Bleeder current
Switching
Voltage
Off
Current
20-18
About 1 A
About 20 V About 3.5 A
36-10
About 1 A
About 10 V About 3 A
60-6
About 0.5 A
About 30 V About 1.5 A
Table 2
Model
Output side Bleeder current
20-18
About 150 mA
36-10
About 80 mA
60-6
About 50 mA
Table 3
Alarm Detector Circuit
This unit employs three alarm detector circuits : Pre
overvoltage, overcurrent, and overheat detector
circuits.
The pre overvoltage detector circuit has a
comparator IC4 1/2, w hich compares the input
voltage. When the input voltage exceeds the level
shown in Table 4, the circuit outputs an alarm signal.
The overcurrent detector circuit has a comparator
IC4
2/2, which outputs an alarm signal w hen the
current detected by IC1 exceeds about 115% of the
full scale level. The IC4
2/2 also serves as an
error amplifier and provides C C control w hen the
output current reaches about 115% of the full scale.
The overheat detector circuit has a TS1
thermal switch on the heat sink. This
sw itch
functions and circuit outputs an alarm signal w hen
the temperature exceeds about 110
.
Model
Detection voltage
20-18
About 30V
36-10
About 50V
60-6
About 75V
Table 4
PDS-20-18(K)
1,1(
98.12.4
12:07
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