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e.
To ensure that the overvoltage crowbar
circuit is operational, rotate the OVERVOLTAGE con¬
trol counterclockwise until the supply crowbars.
Output voltage will fall to approximately one volt
and the OVERVOLTAGE and CURRENT MODE indica¬
tors ( (|) and (|)
, respectively) will light.
/f.
To deactivate the crowbar, return the
OVERVOLTAGE control to maximum clockwise posi¬
tion and turn off supply.
Turn supply back on and
output voltage should again be value obtained in
step (d),
g.
To checkout the constant current circuit,
first turn off supply. Short circuit front panel output
terminals (+ to -).
On the 6114A or 6.115A supplies
set meter switch to AMPS.
Turn on the supply;
CURRENT MODE indicator (?) comes on.
h.
Adjust CURRENT control through the en¬
tire output current range as indicated on meter.
Adjust output for desired operating current.
i.
Remove short and connect load to output
terminals.
Note that for maximum load protection
by the crowbar, the Load should be connected to
the rear terminals.
NOTE
The power supply features automatic
dual-range operation.
If operating
voltage and current are both set above
the mid-points of supply's voltage and
current ratings, the supply will gross
current limit if current attempts to ex¬
ceed one-half the maximum current
rating of the supply.
If output current
increases further, the supply enters
the constant current mode in which
output voltage is reduced in order to
supply the desired current.
The VOLT¬
AGE control setting, therefore, is
overridden.
See paragraph 3-65 for
more details.
3-3
OPERATING MODES
3-4
The power supply is designed so that its
mode of operation can be selected by making strap¬
ping connections between particular terminals on
the terminal strips at the rear of the power supply.
The terminal designations are stenciled on the
power supply above their respective terminals. The
operator can ground either the positive or negative
terminal or operate the power supply up to 3 00Vdc
off ground (floating).
The following paragraphs des¬
cribe the procedures for utilizing the various oper¬
ational capabilities of the power supply.
A more
theoretical description concerning the operational
features of this supply is contained in Application
Note 90 and in various Tech. Letters.
Copies of
these can be obtained from your local Hewlett-
Packard field office.
3-6
The power supply is normally shipped with its
rear terminal strapping connections arranged for
constant Voltage/Constant Current, local sensing,
local programming, single unit mode of operation.
This strapping pattern is illustrated in Figure 3-2.
3-7
The operator selects either a constant voltage
or a constant current output using the front panel
controls (for local programming, no strapping changes
are necessary).
Each supply is rated for two voltage
and current ranges as follows:
Model
Low Range
High Range
Voltage
Current
Voltage Current
6104A/61I4A
6105A/6115A
0-20V
0-50V
0-2A
0-. 8A
20- 40V
50-100V
0-1A
0-.4A
When the VOLTAGE and CURRENT settings are with¬
in the specified ranges, the constant voltage and
constant current modes of operation are selected as
described below.
If, however, VOLTAGE and CUR¬
RENT settings are required that are outside of the
specified ranges for normal operation (for instance,
the 6104A is set for 30V and 1. 5A), the power sup¬
ply provides automatic dual-range
switching if
output current attempts to exceed the low range cur¬
rent rating.
As current is limited (to approximately
65% of the maximum, low range, rating at nominal
line voltage), the VOLTAGE setting is overridden
and output voltage is reduced to the low range
(approximately 65% of the maximum, high range,
voltage rating at nominal line voltage).
The supply
next enters the constant current mode during which
output voltage is reduced in order to supply the de¬
sired current.
Refer to paragraph 3-65 for more in¬
formation on how the supply operates to gross cur¬
rent limit and automatically switch ranges,
3-8
CONSTANT VOLTAGE
3-9
To select a constant voltage output, within
the normal range ratings of the supply, proceed as
follows;
.
a.
Remove load from output terminals; turn¬
on supply and adjust VOLTAGE control for desired
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