Specifications

REMOTE SENSE
In constant voltage mode (CV), the output is locally strapped for local sensing (normal operation); an
unavoidable voltage drop is incurred in the load leads, which adds to its voltage regulation. By connecting the
supply for remote sensing, voltage is sensed at the load rather than at the output terminals. This allows the
supply to automatically compensate for voltage drops in the load leads and improve regulation. In remote
sensing, the MES:VOLT? Query and the front panel meter monitor load voltage at the sensing points.
In remote sensing, the OVP circuit makes measurements at the load sense points. The voltage sensed by the
OVP circuit could be significantly higher than the voltage being regulated at the load. Therefore, set OVP
threshold voltage accordingly.
REMOTE SENSE CHARACTERISTICS
OUTPUT NOISE: Noise picked up on the sense leads will appear at the supply's output and may adversely
affect CV load regulation. Twist the sense leads to minimize external noise pickup and run them parallel and
close to the load leads. In noisy environments, it may be necessary to shield the sense leads. If a shield is
used, ground the shield at the power supply end only and 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. In extreme cases, it can cause oscillation.
It is difficult to state simple rules defining the conditions under which this can occur, and which corrective
action to take. A certain amount of trial and error may be called for. Three guidelines that are almost always
valid are:
a. Keep the leads as short as possible
b. Twist the load leads together to minimize inductance.
c. Shield he sense lead and ground shield at supply.
In most circumstances, once these three guidelines are followed, problems associated with the load lead
inductance will be eliminated. This leaves the load lead resistance and load capacitance as the major cause of
the reduced stability. In this case, you may obtain further improvement to the stability by:
a. Keeping the load capacitance as small as possible.
b. Increasing the diameter of the load leads to reduce resistance.
If heavier gauge leads (# 10 or greater) are used, circumstances may arise when the load lead inductance and
the load capacitance can form an under damped filter. This filter occasionally has the effect of destabilizing
phase response. In this case, the above steps can worsen stability since they will reduce damping in the
system.
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