Ametek XEL Serie Mode D'emploi page 19

To avoid instability and transient response problems, care must be taken to ensure good coupling
between each output and sense lead. This can be done either by twisting the leads together or
by using coaxially screened cables (sense through the inner). An electrolytic capacitor directly
across the load connection point may also be beneficial. The voltage drop in each output lead
must not exceed 0.5 Volts.
Switch the LOCAL/REMOTE switch back to LOCAL when remote sensing is not in use.
Output Connection and Remote Sensing on Programmable Models
All programmable models have duplicate rear panel Output and Sense terminals, appropriate for
when the instruments are used in a rack. When the rear panel Output terminals are used, the
use of remote sense is always recommended to ensure that output regulation is maintained
within specification; connections can be made to either the front or the rear remote sense
terminals but never to both pairs of terminals at the same time. Connect the Sense terminals to
the load, following the guidelines above, and set the LOCAL/REMOTE switch to REMOTE.
If the rear panel Output terminals are used without remote sense make sure that the front panel
switch is set to LOCAL. Regulation will be degraded a little when local sense is used because of
the additional small voltage drop in the wiring to the rear terminals.
Series or Parallel Connection with Other Outputs
The outputs of the power supply are fully floating and may be used in series with other power
supply units to generate high DC voltages up to 300V DC.
The maximum permissible voltage between any terminal and earth ground (
WARNING! Such voltages are exceedingly hazardous and great care should be taken to shield
the output terminals for such use. On no account should the output terminals be touched when
the unit is switched on under such use. All connections to the terminals must be made with the
power switched off on all units.
It should be noted that the unit can only source current and cannot sink it, thus units cannot be
series connected in anti-phase.
The unit can be connected in parallel with others to produce higher currents. Where several units
are connected in parallel, the output voltage will be equal to that of the unit with the highest
output voltage setting until the current drawn exceeds its current limit setting, upon which the
output will fall to that of the next highest setting, and so on. In constant current mode, units can
be connected in parallel to provide a current equal to the sum of the current limit settings.
Protection
The output has intrinsic short-circuit protection and is protected from reverse voltages by a diode;
the continuous reverse current must not exceed 3 Amps, although transients can be much higher.
If the applied reverse voltage can source more current than the set current limit, and the output is
on, then the output will go into current limit (the CC indicator will flash) and its display will show
the reverse voltage across the protection diode; if the output is off, just the CC indicator will flash.
In common with all series regulated single-ended power supplies, the unit is not capable of
sinking current provided from an external source. If a voltage greater than the set output voltage
of the unit is applied from an external source, the internal regulator will turn off and no current will
flow; if the output is turned on the voltage meter will read the applied voltage. No damage will
result providing the applied voltage does not exceed the maximum output voltage of the power
supply by more than 20 Volts.
With the OUTPUT off the load is still connected to the power supply output stage; the output
voltage is simply set to zero. Do not apply external voltages to the power supply terminals in
excess of 20V above the rated output voltage, even with the output off, or damage may result.
) is 300VDC
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