AMETEK Programmable Power XPF Serie Manuel D'instructions page 15

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. For optimum
operation connect the power supplies separately to the load.
Note that the output terminals are rated at 30A maximum; if two or more outputs are operated in
parallel to source higher currents than this the junction should be made at a separate point, not
one of the terminals.
Protection
Over-current protection (OCP) is implemented in firmware and can only be set and used when
under remote control via the RS232, USB, LAN (LXI) or GPIB interfaces (XPF60-10DP only).
Setting resolution is 10mA and typical response times are 500ms. In local mode and for XPF60-
10D, OCP is still active but automatically defaults to 11 Amps.
When the output is tripped the displays will show
Turn the output off; the trip message should be replaced with the normal preset V and I readings.
When the cause of the trip has been removed the output can be switched on again.
Even with the output off the load is still connected to the power supply output stage. Do not apply
external voltages in excess of 70V to the power supply terminals or damage may result.
The output is protected from reverse voltages by a diode; the continuous reverse current must not
exceed 3 Amps, although transients can be much higher.
Over-temperature Protection
Sensors on both the secondary heatsinks will detect over-temperature due to blocked air-flow, fan
failure or other circuit fault. Over-temperature will turn the output off, the OUTPUT indicator will
flash, and the display will show the message
even after the heatsinks have cooled down. When the cause of the over-temperature has been
removed and the heatsinks have cooled to normal working temperatures the output can be reset
by turning the POWER switch off then on again.
If either output temperature trips when the instrument is operating in independent mode then the
other output will continue to operate normally.
If, however, the instrument is operating in Tracking mode then a temperature trip on either output
will turn both outputs off;
trip.
View Settings
Lock Settings
Pressing the LOCK key digitally locks the set voltage and current limit. The settings are stored with
a precision of better than 1 digit. Subsequent adjustments of the VOLTAGE and CURRENT
controls will have no effect.
Because cancelling LOCK will cause the output settings to change if the VOLTAGE and
CURRENT control positions have been moved, warning reminders are given before LOCK is
cancelled. Press and hold the key to cancel LOCK.
If the OUTPUT is off (the safe condition) the display will flash the 'unlocked' settings twice before
the change is implemented; the LOCK lamp goes off.
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Overvoltage protection (OVP) is fully variable within the range 1V to 66V. The OVP limit
is set via the screwdriver adjustable OVP preset potentiometer, accessible through a
hole in the front panel immediately above the OVP key. Rotating the preset clockwise
increases the limit, which can be read directly on the user display by pressing the OVP
key beneath the preset. If the voltage on the output exceeds the set OVP for any
reason, including an externally forced voltage, the output will be tripped off.
OtP trip
The set voltage and current limit are always shown when the
output is off but can also be viewed when the output is on by
pressing the VIEW key; the VIEW lamp is lit whilst the VIEW key
is pressed.
OUP triP
. The output will remain shut down
OtP trip
will show only in the display of the output which caused the
. and the OUTPUT lamp will flash.