KEPCO BOP 5-20DL, Operator'S Manual

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3-6
BOP 5-20DL 081915
3.3.2 LOCAL CONTROL OF CURRENT LIMITING
Figure 3-3 shows the Current Limiting circuit configured for local sensing and local (front panel)
control.
FIGURE 3-3. BOP (±) CURRENT LIMITING CIRCUIT (LOCAL CONTROL, LOCAL SENSING)
The output current is sensed by the current sensing resistor R
S
. The voltage drop across R
S
is
proportional to the output current value and is amplified by the Current Sensing amplifier and
applied to the input to the (–)
I
O
Limit Comparison amplifier and to the (+)
I
O
Limit Comparison
amplifier. In the local (front panel) control mode, as well as in the external control mode, a 0 to
10 volt signal, applied at the inverting inputs of the ±
I
O
Limit Comparison amplifiers, will control
the current limit point over the entire output current range of each BOP model: 0.25% to 105%
of nominal for local control, and 0.25% to 110% of nominal for remote control. For the internal
(front panel) control mode, the control signal is derived across both 10 volt reference sources,
applied by means of the ±
I
O
Limit controls to the internal ±
I
O
Limit amplifiers and directed to
the respective inputs of the ±
I
O
Limit Comparison amplifiers. In the internal control mode, both
±
I
O
Limit Amplifiers (EXT) are biased off by the 15V bias source.
3.3.3 CURRENT MODE OPERATION WITH VOLTAGE LIMITING.
The BOP may be used as a stabilized d-c source of positive or negative current, with output
voltage limiting (for either polarity), pre-selected for the application at hand. Figure 3-4 illustrates
the current control circuit configured for local (front panel) control using local sensing.
With CURRENT CONTROL switch (12, Figure for 3/4 rack, Figure 2-1 for full rack) set to ON
(closed), and MODE switch (8) set to CURRENT, output current can be controlled by means of
the CURRENT CONTROL (13) over the full output range. The control potential (zero to ±10V) is
applied via Preamp “B,” operating with unity gain, to the l
O
Comp. Amp which drives the Power
Stage with a fixed gain as listed in Table 1-2.
3043685
+
22
28
C
+
10V
10V
POWER
STAGE
-
+
G
A
T
E
-
+
+
-
8
34
1
+
+
-
+
-
+
-
(+)
I
o LIMIT-
AMP (EXT)
(+)
I
o LIMIT-
AMP (INT)
(-)
I
o LIMIT-
AMP (INT)
(-)
I
o LIMIT-
AMP (EXT)
(+)
I
o LIMIT
CONTROL
BIAS 15V
(-)
I
o LIMIT
CONTROL
(+)
I
o LIMIT-
COMP AMP
(-)
I
o LIMIT-
COMP AMP
DRIVER
COMMON
BOP
I
o
LIMIT CHANNEL
PART OF REAR PROGRAMMING CONNECTOR
57.6K
57.6K
LOAD
-
+
S
R
COM
S
OUT
S
NOTES:
1. Local Sensing shown (links installed
between COM and S and between
OUT and S terminals).
2. On rear programming connector install
jumpers between terminals (1) and (34)
and between (34) and (8).
CURRENT
SENSE AMP
I
o CAL
SIGNAL
GROUND