HP 6826A - Page 21

3-64
REVERSE VOLTAGE AND CURRENT LOADING
68 A9 AIO All A12 AI3 AI4
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MASTER
(POWER SUPPLY OR
VARIABLE GAIN AMPL
MODE, LOCAL/AUTO
SWITCH IN LOCAL ) .
SLAVE t
(FIXED GAIN AMPL.
MODE, LOCAL/AUTO
SWITCH IN AUTO ).
SLAVE 2
(FIXED GAIN AMPL.
MODE, LOCAL/AUTO
SWITCH IN AUTO ) .
Figure 3-13. Auto-Parallel Connections, Three Units
3-62 BIPOLAR OVERVOLTAGE AND OVERCURRENT
LIMIT
3-63 Bipolar overvoltage and overcurrent limit circuits
prevent excessive BPS/A voltage or current outputs. The
voltage limiting circuit prevents the output voltage from ex¬
ceeding approximately ±55 volts (6826A) or ±110 volts
(6827A). The current iimiting circuit limits the transient
output current to a value approximately two times the max¬
imum rated output of 1.0A (6826A) or 0.5A (6827A).
3-65 Current limit circuits also protect the BPS/A from
active loads that force energy in or out of the BPS/A (sink
condition). This can appear as current fiow into the HI
OUT (+) terminal when the terminal is positive, or current
fiow out of the terminal when it is negative. Figure 3-14
shows the normal operating locus of the BPS/A. As shown,
the 6826A BPS/A will limit the sink current to a value
ranging linearly from 1A at OV to 0.5A at 50V and the
6827A BPS/A will limit sink current to a value ranging lin¬
early from 0.5A at 0V to 0.25A at 100V.
3-66 An active load can easily be accommodated by the
BPS/A as long as the following precautions are adhered to:
a. The active load must not be applied unless the BPS/A
is in its active state.
b. Program to zero output before disconnecting load.
CAUTION
Externally applied voltage to output terminals
in excess of 60V (6826A) or 125V (6827A)
could damage the instrument.
+ V
r
\
+ 50V(6826A)
+-IOOV(6827A5
j SINK
SOURCE
j - !A(6826A)
/ -0.5A16827A)
/
+ 1A(6826A5
+ 0.5A(6827A)
\
0
/
SOURCE
SINK J
~!00V(6827A)
-50V56826A)
\
_J
V
Figure 3-14. 6826A/6827A Output Ranges
3-12