HP 6826A Service Manual

switch) and also selects either constant voltage or a constant
current output using the front pane! VOLTAGE and CUR¬
RENT controls (for local programming, no strapping changes
are required). Constant voltage or constant current opera¬
tion are selected as described in the following paragraphs.
(LOCAL Programming)
3-27 Constant Voltage. To select a constant voltage
output, proceed as follows;
a. Remove load from output terminals; turn-on supply
and adjust VOLTAGE control for desired output voltage.
b. Short output terminals and adjust CURRENT con¬
trol for maximum output current allowable (current limit)
as determined by load conditions and voltage range selected
in step (a). If a load change takes place and causes the out¬
put current to exceed this setting, the power supply will
automatically crossover to constant current mode and out¬
put current will be constant at the level set by the CURRENT
control. The CURRENT MODE indicator will come on and
output voltage will drop proportionately to maintain con¬
stant current.
3-28 Constant Current. To select a constant current
output, proceed as follows;
a. Short output terminals and adjust CURRENT con¬
trol for desired output current.
b. Open output terminals and adjust VOLTAGE con¬
trol for maximum output voltage allowable as determined
by load conditions and current selected in step (a). If a
load change causes the voltage to rise, the power supply will
automatically crossover to constant voltage at the voltage
setting and output current will drop proportionately,
3-29 OPERATION OF SUPPLY BEYOND RATED
OUTPUT
3-30 The shaded area on the front panel meters indicate
the amount of output voltage and current that is available
in excess of normal rated output. Although, the BPS/A can
be operated in this region without damage, it cannot be
guaranteed to meet all of its performance specifications.
3-31 REACTIVE LOAD CONSIDERATIONS
3-32 The life and performance of the instrument can
be preserved if the following simple precaution is observed
when driving reactive loads. Always set/program the VOLT¬
AGE control for zero output before removing a capacitive
load or interrupting an inductive load.
3-33 CONNECTING LOAD
3-34 Each load should be connected to the power sup¬
ply output terminals (front or rear) using separate pairs of
connecting wires. This will minimize mutual coupling ef¬
fects between loads and will retain full advantage of the
low output impedance of the power supply. Each pair of
connecting wires should be as short as possible and twisted
or shielded to reduce noise pickup. (If a shielded pair is
used, connect the shield to ground at the power supply and
leave the other end unconnected.)
3-35 If load considerations require that the output power
distribution terminals be remotely located from the power
supply, then the power supply output terminals should be
connected to the remote distribution terminals via a pair of
twisted or shielded wires and each load should be separately
connected to the remote distribution terminals. For this
case, remote sensing should be used. (Refer to Paragraph
3-39).
3-36 Always use two leads to connect the load to the
supply, regardless of where the setup is grounded. This will
eliminate any possibility of output current return paths
through the power source ground. The supply can also be
operated up to 300Vdc above ground if neither output ter¬
minal is grounded.
3-37 REMOTE SENSING
3-38 Remote sensing is used to maintain good regulation
at the load and reduce the degradation of regulation which
would occur due to the voltage drop in the leads between
the power supply and the load. Remote sensing is accom¬
plished by utilizing the strapping pattern shown in Figure
3-5. The power supply should be turned off before chang¬
ing strapping patterns. The leads from the sensing (±S)
terminals to the load will carry much less current than the
load leads and it is not required that these leads be as heavy
as the load leads. However, they must be twisted or shielded
to minimize noise pickup.
3-5

HP 6826A Specifications

General

Brand	HP
Model	6826A
Category	Power Supply
Language	English