Product specifications

127
Power Products AC Power and Load Connections
Applications Information
More detailed specifications at www.agilent.com/find/power
A modern stabilized DC power sup-
ply is a versatile high performance
instrument capable of delivering
a constant or controlled output
reliably and with little attention.
But to take full advantage of the
performance characteristics
designed into a supply, certain basic
precautions must be observed when
connecting it for use on the lab bench
or installing it in a system. Factors
such as wire ratings, system ground-
ing techniques, and the particular
way that AC input, DC output, and
remote error sensing connections
are made can contribute materially
to obtaining the stable, low noise
output expected by the user. Careful
attention to the following guidelines
can help to ensure the trouble free
operation of your Agilent power
supply.
AC Power Input Connections
Wire Rating
RULE 1. When connecting AC power to
a power supply, always use a wire size
rated to carry at least the maximum
power supply input current.
If a long cable is involved, make
an additional check to determine
whether a still larger wire size might
be required to retain a sufficiently
low impedance from the service
outlet to the power supply input ter-
minals. As a general guideline, input
cables should be of sufficient size
to ensure that the voltage drop at
maximum rated power supply input
current will not exceed 1% of the
nominal line voltage.
Continuity
RULE 2. Maintain the continuity of the
AC, acc, and grounding wires from the
AC power outlet to the power supply
input terminals without an accidental
interchange.
Interchanging the AC and grounding
wires may result in the power sup-
ply chassis being elevated to an AC
potential equal to the input line
voltage. If the chassis is grounded
elsewhere, the result may be no
worse than some blown fuses. But
if the chassis is not grounded, the
result could be a potentially lethal
shock hazard. Confirm that the
cha ssis is grounded by the
grounding wire.
Transformers
RULE 3. If an autotransformer or an
isolation transformer is connected
between the AC power source and the
power supply input terminals, it should
be rated for at least 200% of the
maximum rms current required by
the power supply.
The transformer must have a higher
rating than would be suggested by
the supply’s rms input current
because a power supply input circuit
does not draw current continuously.
Input current peaks can cause a
smaller transformer to saturate,
resulting in failure of the supply to
meet its specifications at full output.
RULE 4. Be sure to connect the common
terminal of an autotransformer to the
acc (and not the AC) terminals of both
the power supply and the input power
line.
If acc is not connected to the
common terminal of the autotrans-
former, the power supply’s input
acc terminal will have a higher than
normal AC voltage connected to it,
contributing to a shock hazard and,
in some instances, a greater output
ripple.
AC Line Regulator
RULE 5. Do not use an AC line regulator
at the input to a regulated power supply
without first checking with the power
supply manufacturer.
Some regulators tend to increase the
impedance of the line in a resonant
fashion and can cause power sup-
plies to malfunction, particularly if
they use SCR or switching regulators
or preregulators. Moreover, since
the control action of many line volt-
age regulators is accompanied by
a change in the output waveshape,
their advantage in providing a
constant rms input to a power
supply is small. In fact these
changes in waveshape are often
just as disruptive in causing power
supply output changes as the origi-
nal line voltage amplitude changes
would have been.