HP 6269B Operator’s, Organizational, Direct Support And General Support Maintenance Manua L page 16

TM 11-6625-2958-14&P
Figure 3-2. Normal Strapping Pattern
3-7 CONSTANT VOLTAGE
3-8 To select a constant voltage output, proceed
as follows:
a. Turn on power supply and adjust VOLTAGE
controls for desired output voltage with output ter-
minals open.
b. Short circuit output terminals and adjust
CURRENT controls for maximum output current al-
lowable (current limit), as determined by load con-
ditions. If a load change causes the current limit
to be exceeded, the power supply will automatical-
ly cross over to constant current output at the pre-
set current limit and the output voltage will drop
proportionately. In setting the current Iimit, al-
lowance must be made for high peak currents which
can cause unwanted crossover. (Refer to Paragraph
3-60. )
3-9 CONSTANT CURRENT
3-10 To select a constant current output, proceed
as follows:
a. Short circuit output terminals and adjust
CURRENT controls for desired output current.
b. Open output terminals and adjust VOLT-
AGE controls for maximum output voltage allowable
(voltage limit ), as determined by load conditions.
If a load change causes the voltage limit to be ex-
ceeded, the power supply will automatically cross
over to constant voltage output at the preset volt-
age limit and the output current will drop propor-
tionately. In setting the voltage limit, allowance
must be made for high peak voltages which can
cause unwanted crossover. (Refer to Paragraph 3-60.)
3-11 OVERVOLTAGE TRIP POINT ADJUSTMENT
3-12 The crowbar trip voltage can be adjusted by
using the screwdriver control on the front panel.
The trip voltage range is as follows:
6 2 6 1 B
6259B, 6260B
2 to 12Vdc 2 to 23Vdc
When the crowbar trips, the output is shorted and
the amber indicator on the front panel lights.
Clockwise rotation of the control produces higher
trip voltages. The factory sets the control fully
clockwise. The crowbar may be disabled complete-
ly if desired. (Refer to Paragraph 5-11 1.)
3-13 False crowbar tripping must be considered
when adjusting the trip point. If the trip voltage is
set too close to the operating output voltage of the
supply, a transient in the output will falsely trip
the crowbar. It is recommended that the crowbar be
set higher than the output voltage by 5% of the out-
put voltage plus 2 volts. However, If occasional
crowbar tripping on unloading can be tolerated, the
crowbar trip point can be set much closer to the
operating out put voltage of the supply.
3-14 CONNECTING LOAD
3-15 Each load should be connected to the power
supply output terminals using separate pairs of
connecting wires. This will minimize mutual cou-
pling effects between loads and will retain full ad-
vantage 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
one end of the shield to ground at the power supply
and leave the other end unconnected.)
3-16 If load considerations require that the output
power distribution terminals be remotely located
from the power supply, then the power suppIy out-
put 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 3-4 1.)
3-17 Positive or negative voltages can be obtained
from this supply by grounding either one of. the out-
put terminals or one end of the load. Always use
two leads to connect the load to the supply, regard-
less of where the setup is grounded. This will elim-
inate any possibility of output current return paths
through the power source ground which would dam-
age the line cord plug. This supply can also be
operated up to 300Vdc above ground, if neither out-
put terminal is grounded.
3-18 NO LOAD OPERATION
3-19 When the supply is operated without a load,
down-programming speed is considerably slower
than in normal loaded operation. This slower pro-
gramming speed is evident when using any method
of down-programming - either turning the VOLTAGE
6268B, 6269B
controls fully counterclockwise, activating the
4 to 45Vdc crowbar, or throwing the LINE circuit breaker to
OFF. Under any of these conditions, the supply
output will rapidly fall to approximately two volts,
3-2