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The LIMIT current value is not displayed, but the adjustment is linear. For
example, setting the LIMIT knob half-way between 0 and 2 Amps will limit the
output current to 1 Amp. A more accurate LIMIT setting may be attained by the
following procedure.
1
2
3
Main Control Knob
The main control knob is used whenever the SET Resistance is adjusted. Turning
this knob clockwise (CW) increases the value on the display.
OUTPUT Off/On Switch
The OUTPUT off/on switch is located in the lower right-hand corner of the front
panel. This switch has a toggling action which turns the output current of the
LDT-5412 on and off. When the output is active, the LED indicator just above the
switch will be lit.
When the OUTPUT is off, it is safe to connect or disconnect sensitive devices
from the LDT-5412, even though the power supply itself is on.
The OUTPUT is off when AC power is first applied to the instrument. Additionally,
there are two other conditions which will automatically cause the output to reset to
the off state:
• Power Drop-outs - AC line power drop-outs lasting more than about 1 second will trigger an
• OPEN THERM - If the externally connected thermistor or set point resistor is open, the output
If any of these conditions occur and the OUTPUT goes off, the output may be
turned on again by first correcting the cause of the fault and then pressing the
OUTPUT off/on switch.
05_11
Connect a short between pins 2 and 3 of J301 (TE OUTPUT connector on rear panel).
Connect a 10 Kohm resistor across pins 7 and 8 of J301.
Set the DISPLAY MODE switch to TE CURRENT. Turn the OUTPUT switch on (LED lit).
Adjust the Main Control Knob fully counter-clockwise (CCW).
Adjust the LIMIT control until the display reads the desired limit current. Turn the OUTPUT
off, remove the short from pins 2 and 3 of J301, and remove the resistor form pins 7 and 8
of J301.
During operation the TE output current is unconditionally limited to the value set by the
LIMIT adjustment.
internal power monitor and cause the output to switch unconditionally to the off state. This
sequence is also initiated when the LDT-5412 is switched off or unplugged.
is switched to the off state and the OPEN THERM indicator is activated. (See also Section
2.3.7, Fault Indicators.)
O P E R A T I O N
Front Panel
LDT-5412
2
C H A P T E R
5
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