HP 6268B Operating And Service Manual

SECTION I
GENERAL INFORMATION
1-1 DESCRIPTION
1 -2 The five constant-voltage/constant current power
supply models included in this manual use a transistor
series-regulator combined with a triac preregulator for high
efficiency, excellent regulation, and low ripple and noise.
These supplies are packaged in 7-inch high full-rack-width
cabinets that are suitable for either bench or relay rack
operation.
1 -3 The outputs of these supplies can be varied from
zero to full rated voltage or current by setting coarse and
fine voltage and current controls on the front panel or they
can be programmed remotely by resistance or voltage inputs
to rear panel terminals. When the voltage controls are used
to establish a constant output voltage, the current controls
establish a current limit that can protect the load from over¬
current. When the current controls are used to establish a
constant output current, the voltage controls establish a
voltage limit that can protect the load from excessive
voltage. The crossover from constant-voltage to constant-
current operation, or vice versa, occurs automatically when
the load current reaches the value established by the current
controls or the voltage reaches the value established by the
voltage controls. The output voltage and current can both
be monitored continuously on front panel meters.
1-4 Output loads are further protected by a built-in
fast-acting overvoltage protection crowbar circuit that
automatically shorts the supply's output terminals if a
preset voltage limit is exceeded. A front panel control sets
the voltage at which the crowbar trips and can be adjusted
from approximately 10% to 110% of the supply's maximum
rated voltage. When several supplies are installed in the
same system, whether in series, parallel, or independently,
their crowbar circuits can be interconnected so that all will
trip simultaneously whenever any one of them does.
1 -5 These power supplies are forced air cooled.
1-6 The ac input connections to these supplies are made
at rear panel terminals. All dc output, remote sensing, and
remote programming connections are also made at rear
panel terminals. Either the positive or negative output
terminal of a supply may be grounded or the supply's
output may be floated at up to 300 volts above ground.
1-7 Remote programming, remote sensing, and several
methods of operating supplies in combination of two or
three are made possible by rear panel terminals that allow
access to control points within the regulator circuits. These
capabilities are described below.
a. Remote Programming. The power supply's output
voltage or current (or both) can be controlled from a remote
location by varying a resistance or a voltage input signal to
the supply's voltage or current regulator circuit.
b. Remote Sensing. Connecting the voltage regulator's
feedback circuit to the load terminals rather than to the
supply's output terminals prevents the voltage drop in the
load leads from impairing voltage regulation at the load
when operating in the constant voltage mode. A separate
pair of sensing leads which carry no load current extend
the feedback loop to the load terminals.
c. Auto-Parallel Operation. Two or three similar
supplies connected in parallel can be made to share loads
equally and can be controlled by the voltage and current
controls (or remote programming terminals) of one of the
supplies designated the master if they are connected for
auto-parallel operation. Normally, only supplies having
the same model number are connected in auto-parallel, but
auto-parallel operation can be used with any of the supplies
covered by this manual that have equal current capabilities.
d. Auto-Series Operation. Two or three supplies can
be connected in series and have their outputs simultaneously
controlled by the voltage and current controls (or remote
programming terminals) of one of the supplies designated
the master. The voltage contributed by each slave is main¬
tained in a constant ratio to that of the master. These
ratios can be set as desired. Auto-series operation provides
higher output voltages in constant voltage operation and
greater voltage compliance in constant current operation.
Any HP supply that offers auto-series operation can serve
as a slave supply; the master supply does not have to be an
auto-series model.
e. Auto-Tracking Operation. Auto-tracking is similar
to auto-series operation except that two or three supplies
share a common negative output bus and are interconnected
so that the output voltage of each slave supply is maintained
at some constant fraction of that of the master supply. All
of the supplies are controlled through the master supply,
and each supply feeds a separate load.
1-8 SPECIFICATIONS
1-9 Detailed specifications for these power supplies
are given in Table 1 -1.
M

HP 6268B Specifications

General

Brand	HP
Model	6268B
Category	Power Supply
Language	English