HP 6038A - Page 42

3-220 UP to two or more power supplies can have their out¬
puts connected in series to provide increased output voltage.
Each power supply is programmed via HP-iB with hold on, and
then all units are tirggered at once. Multiple loads may be con¬
nected in series, and the combination may be grounded at any
one point to provide both positive and negative outputs.
Regardless of whether or where the load is grounded, no point
may be more than -1-240 volts from ground. Add the voltage
settings of each power supply together to determine the total
output voltage. Set the current limits for each power supply
to the maximum that the ioad can handle without damage.
3-221 Fault Input (FLT) and Remote
Inhibit (HMH)
3-222 The connections for FLT and INH are made through
J8 which is located on the rear of the power supply just below
the HP-IB address / PON selection switches. The connector
(JS), is supplied with its mating plug which provides a conve¬
nient way to access the FLT and INH circuitry (see Figure 3-161.
To remove the plug grip it firmly, then pull it straight out of
J8. With a small screwdriver, loosen the terminal screws on
the plug; connect the external FLT and/or INH circuitry, then
install the plug back into the connector. Note that in order to
prevent radio frequency interference (RFI), shielded or twisted
pair wiring should be used for the FLT and INH connections.
To prevent ground loops (if shielded wire is used) connect on¬
ly one end of the shield to chassis ground. Several examples
follow.
3-223 In Figure 3-17, an externally, normally open switch
(S1) is mounted on a hinged protection hood which covers the
power supply output terminals. The terminals of the switch are
connected to the INH input line. When the hood is lifted, the
switch closes and the following simultaneous actions are taken
by the power supply:
1 .The power supply is disabled (as it is when an OUT OFF
or OUT 0 is isued).
2. The Rl bit in the status and astatus registers is set
true (1).
3. The FLT line goes true (1) (provided the Rl bit in
the unmasked register has been set true (D).
4. If the Rl bit in the unmasked register has been set
true (1), then the Rl bit in the fault register will be
set true (1), and FAU bit in the serial poll register will
be set true (1).
Closing the hood will not re-enable the supply, and during a
serial poll the controller would be made aware that a fault
exists via the FAU bit In the serial poll register. The fault register
must now be read to reset the FLT and Rl bit. Finally sending
CLR will initialize the supply to its power on state (See Table
3-6).
POWER SUPPLY
Figure 3-17. INH Example
POWER SUPPLY
Figure 3-18. FLT Example
3-29