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REMOTE OPERATING MODES
Remote operating modes discussed below are remote voltage
sensing and remote voltage programming. You can set up the unit
for remote operating modes by changing the settings of the rear
panel switch and connecting the leads from the rear panel termi-
nals to the load or the external voltage. Solid conductors of 0.75
2
to 1.5 mm
can be connected to the rear panel terminals by sim-
ply push fitting. Thinner wires or conductors are inserted into the
connection space after depressing the orange opening lever.
Turn off the supply while making changes to rear panel switch
settings or connections. This avoids the possibility of damage
to the load and OVP shutdown from unintended output.
Remote Voltage Sensing
Remote voltage sensing is used to maintain good regulation at the
load and reduce the degradation of regulation that would occur due
to the voltage drop in the leads between the power supply and the
load. By connecting the supply for remote voltage sensing, voltage
is sensed at the load rather than at the supply's output terminals.
This will allow the supply to automatically compensate for the volt-
age drop in the load leads and improve regulation.
When the supply is connected for remote sensing, the OVP circuit
senses the voltage at the sense leads and not the main output
terminals.
Remote voltage sensing compensates for a voltage drop of
up to 0.5 V in each load, and there may be up to a 0.1 V
drop between the output terminal and the internal sensing
resistor, at which point the OVP circuit is connected. There-
fore, the voltage sensed by the OVP circuit could be as
much as 1.1 V more than the voltage being regulated at the
load. It may be necessary to re-adjust the OVP trip voltage
when using remote sensing.
CV Regulation. Notice that any voltage drop in the sense leads
adds directly to the CV load regulation. In order to maintain the
specified performance, keep the sense lead resistance to 0.5
ohms per lead or less.
Remote Sensing Connections. Remote sensing requires
changing settings of the rear panel switch and connecting the
load leads from + and - output terminals to the load and connect-
ing the sense leads from the +S and -S terminals to the load as
shown in Figure 5.
Observe polarity when connecting the sensing leads to
the load.
Output Noise. Any noise picked up on the sense leads will
appear at the supply's output voltage and may degrade CV load
regulation. Twist the sense leads to minimize the pickup of exter-
nal noise and run them parallel and close to the load leads. In
noisy environments, it may be necessary to shield the sense
leads. Ground the shield at the power supply end only. Do not use
the shield as one of the sensing conductors.
Stability. When the supply is connected for remote sensing, it is
possible for the impedance of the load wires and the capacitance
of the load to form a filter, which will become part of the supply's
CV feedback loop. The extra phase shift created by this filter can
degrade the supply's stability and can result in poor transient
response performance or loop stability. In extreme cases, it can
cause oscillations. Keep the leads as short as possible and twist
the leads of the load to eliminate the load lead inductance and
keep the load capacitance as small as possible.The load leads
should be of the largest diameter practical, heavy enough to limit
the voltage drop in each lead to 0.5 volts.
The sense leads are part of the supply's programming feedback
control loop. Accidental open-connections of sense or load leads
during remote sensing operation have various unwanted effects.
Provide secure, permanent connections-especially for the sense
leads.
During remote sensing setup, it is strongly recommended to
power off (by presssing power ON/OFF button) the power supply
to avoid undesirable damage to the load or the power supply.
l
LOCAL
MASTER
M/S 1
M /S 2
CV
CC
SLAVE
REMOTE
+
LOAD
_
Figure 5. Remote Voltage Sensing
Remote Analog Voltage Programming
Remote analog voltage programming permits control of the regu-
lated output voltage or current by means of a remotely varied volt-
age. The programming (external) voltage should not exceed 10
volts. The stability of the programming voltages directly affects
the stability of the output. The voltage control on the front panel is
disabled during remote analog programming.
The supply includes clamp circuits to prevent it from
supplying more than about 120% of rated output voltage
or current when the remote programming voltage is
greater than 10 Vdc. Do not intentionally operate the sup-
ply above 100% rated output. Limit your programming
voltage to 10 Vdc.
1-10
_
_
_
+
+
+
SENSE
OUT
+S
-S
CV
CC
VREF A1 A2 A3 A4 A5
NOTE: Twist sense leads and load leads
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