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3-21
if load considerations require the use of output
distribution terminals that are located remotely from the sup¬
ply, then the power supply output terminals should be con¬
nected to the remote distribution terminals by a pair of twisted
or shielded wires and each load should be separately con¬
nected to the remote distribution terminals. Remote voitage
sensing is required under these circumstances (Paragraph
3-30). Sense either at the remote distribution terminals, or (if
one load is more sensitive then the others) directly at the most
critical load.
3-22
Either positive or negative voltages can be obtained
from the supply by grounding one of the output terminals. It is
best to avoid grounding the output at any point other than the
power supply output terminals to avoid regulation problems
caused by common-mode current flowing through the load
leads to ground. Always use two wires to connect the load to
the supply regardless of where or how the system is ground¬
ed. Never ground the system at more than one point. This
supply can be operated with either output terminal up to ± 240
volts dc (including output voltage) from ground.
3-23
The PARD specifications in Table 1-1 apply at the
power supply output terminals. However, nosie spikes in¬
duced in the load leads at or near the load may affect the load
although the spikes are inductively isolated from the power
supply. To minimize voltage spikes at the load, connect a
bypass capacitor as shown in Figure 3-4. With this setup,
peak-to-peak noise at the load can actually be reduced to a
level well below the value specified at the 8G34A output
terminals.
Figure 3-4. Connecting a Bypass Capacitor
3-24
Overvoltage Protection fOVP)
3-25
The overvoltage trip point can be adjusted at the
front panel or remotely via HP-IB. OVP will trip at the lower of
the two values, regardless of whether the 6G34A is in local or
remote control. The approximate trip voltage range is from
two volts to 64.5 volts. When the OVP circuit trips, the supply
is inhibited and delivers no output power, and the OVP in
dicator turns on. See note following Paragraph 3 32 for OVP
adjustment with remote sensing.
3-26
Local Adjustment. OVP is set locally by the re¬
cessed single-turn OVP ADJUST potentiometer on the front
panel. Rotating the control clockwise sets the trip voltage
higher, (It is set to maximum at the factory.) When adjusting
the OVP trip point, the possibility of false tripping must be
considered. If the trip voltage is set too close to the supply's
operating voltage, a transient in the output would falsely trip
the OVP. For this reason it is recommended that the OVP trip
voltage be set higher than the output voltage by at least 1.5
volts +1 % of the output, voltage. To adjust the OVP trip
voltage at the front panel, proceed as follows:
a. Turn on supply and hold OVP DISPLAY pushbutton in.
OVP SET indicator to right of voltmeter turns on to in¬
dicate that voltmeter is displaying the OVP trip voltage.
b. Insert a small-blade screwdriver through hole in front
panel and adjust OVP trip voltage to desired level,
3-27
Local OVP Reset. To reset the OVP locally, the ac
LINE switch must be turned off for a least one second and
then back on. The cause of the overvoltage must be removed
before the OVP circuit is reset, or the circuit will trip again
immediately. Turning ac power off and back on will reset OVP
regardless of whether the trip voltage was set locally or
remotely. If the OVP circuit trips continuously check the load
and/or the trip voltage.
3-28
Remote Adjustment. OVP is set remotely as a
function of the soft voltage limit sent to the SQ34A (see
Paragraph 3-117). The OVP trip voltage is two volts plus 1.04
times the soft voltage limit. For example, if a soft voltage limit
of 30 V is set, the OVP trip voltage will be 33,2 V
([1.04x30} + 2), Because the 6034A initializes at power on with
a soft voltage limit of 60 V, the remote OVP initializes at 64.5
V. Remember that the lower OVP trip voltage, either locally or
remotely set, is the level displayed by OVP DISPLAY and the
level at which the unit trips, regardless of whether the unit is in
local or remote control.
3-29
Remote OVP Reset, OVP is reset remotely by send¬
ing "R" (Reset) to the 6034A (see Paragraph 3-124). The cause
of the overvoltage must be removed before the OVP circuit is
reset, or the circuit will trip again immediately. Sending "R" to
the 6034A will reset OVP regardless of whether the trip voltage
was set locally or remotely. If the OVP circuit trips continu¬
ously check the load and or the trip voltage.
3-30
Remote Voltage Sensing
3-31
Because of the unavoidable voltage drop developed
in the load leads, the strapping pattern shown in Figure 3-3 will
not provide the best possible voltage regulation at the load.
The remote sensing connections shown in Figure 3-5 improve
the voltage regulation at the load by monitoring the voltage
there instead of at the supply's output terminals. (The advan¬
tages of remote sensing apply only during constant voltage
operation.) When using remote sensing, turn off the power
supply before changing the rear-panel strips, sense leads, or
load leads. The following paragraphs discuss some precau¬
tions that should be observed when making a remote sensing
installation.
3-32
The load leads should be of the heaviest practicable
wire gauge, at least heavy enough to limit the voltage drop in
3-6
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