O P E R A T I O N
Installation
01_04
LDX-3412
5
C H A P T E R
2
Under all modes of operation the output current is unconditionally limited to the
value set by the LIMIT adjustment.
Output Current Adjustment
The output current adjustment knob is located in the top right-hand corner of the
front panel. Turning this knob clockwise (CW) will increase the output current. The
output current will be displayed on the LED display during CONST P or CONST I
operation.
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
LDX-3412 on and off. When the output is active, the LED indicator just above the
switch will be lit.
When the output is off, a low impedance shunt is activated across the output
terminals. In this state it is safe to connect or disconnect sensitive devices from
the LDX-3412, even though the power supply itself is on. When the LDX-3412 is
first turned on, the OUTPUT off/on switch is inhibited for several seconds. This
forces the internal, low impedance shunt to remain active across the output
terminals until the LDX-3412 control circuits are stabilized. Additionally, there are
four 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 10 msec will trigger an
internal power monitor and cause the output to switch unconditionally to the off state. This
sequence is also initiated when the LDX-3412 is switched off or unplugged.
• Open Circuit - If the compliance voltage of the externally connected circuit exceeds about 6
volts, the output is switched to the off state and the OPEN CKT indicator is activated. Most
commonly this occurs when the OUTPUT off/on switch is pressed without a load attached.
• Mode Changes - Changing the position of the MODE selector switch resets the output to
the off state.
• Interlock - If the interlock circuit is broken, the output is reset to the off state.
If any of these conditions occur, the output may be turned on again by simply
pressing the OUTPUT off/on switch, after corrective action is taken (if needed).
Fault Indicators
The LDX-3412 has two visual front panel fault indicators, OPEN CKT and LIMIT.
• OPEN CKT - indicates that the compliance voltage required at the LDX-3412 output
terminals has exceeded approximately 6 volts. Most commonly this happens when there is
no load attached to the output or the load becomes disconnected when the output is active.
When an OPEN CKT condition occurs, the LDX-3412 output is automatically turned off and
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