HP 6269B Operator’s, Organizational, Direct Support And General Support Maintenance Manua L page 20

TM 11-6625-2958-14&P
3-43 For reasonable load lead lengths, remote
sensing greatly improves the performance of the
supply. However, if the load is located a consid-
erable distance from the supply, added precautions
must be observed to obtain satisfactory operation.
Notice that the voltage drop in the load leads sub-
tracts directly from the available output voltage
and also reduces the amplitude of the feedback er-
ror signals that are deveIoped within the unit. Be-
cause of these factors it is recommended that the
drop in each load lead not exceed 0.5 volt. If a
larger drop must be tolerated, please consult an
HP Sales Engineer.
Due to the voltage drop in the load
leads, it may be necessary to read-
just the current limit in the remote
sensing mode.
3-44 Observance of the precautions in Paragraph
3-43 will result in a low dc output impedance at
the load. However, another factor that must be
considered is the inductance of long load leads.
This causes a high ac Impedance and could affect
the stability of the feedback loop seriously enough
to cause oscillation. If this is the case, it is
recommended that the following actions be taken:
a. Adjust equalization control R47 to remove
oscillation, or to achieve best possible transient
response for given long load lead configuration.
Refer to Paragraph 5-27 for discussion of transient
response measurement.
b. If performing adjustment in step (a) above
does not remove oscillation, disconnect output
capacitor A3C3 and connect a capacitor having sim-
ilar characteristics (approximately the same capa-
citance, the same voltage rating or greater, and
having good high frequency characteristics) direct-
ly across load using short leads. Readjust equali-
zation control R47 as in step (a) above after making
this change. In order to gain access to capacitor
A3C3, it is necessary to remove the RFI assembly
as described in steps (a) through (c) of Paragraph
5-67. Lead from positive side of capacitor (shown
arrowed In Figure 7-2) can then be unsoldered from
A3 interconnection circuit board.
3-45 To employ remote sensing with any method of
remote programming or with any method of combin-
ing more than one supply discussed in the Preced-
ing or following paragraphs, use the following pro-
cedure:
a. Remove the two external leads connecting
the sensing terminals (±S) to the output bus bars
(±OUT).
b. Connect a lead from the +S terminal to the
positive side of the load, and connect another lead
NOTE
from the -S terminal to the negative side of the load.
Note that there may be more than one lead connect-
ed to the +S and -S terminals.
3-46 AUTO-PARALLEL OPERATION (Figure 3-10)
3-47 Two or more power supplies can be connected
in an Auto-Parallel arrangement to obtain an output
Figure 3-10. Auto-Parallel Operation,
Two and Three Units
3-6