Wavelength Electronics LFI-3500 Series, User Manual

Page: 11 / 38

11
Temp Limit LED:
This LED lights red whenever the load temperature exceeds the
limit temperature set by the Temp Limit Trimpot. The output current is switched off
when this error occurs.
Temp Limit Trimpot:
This adjusts the Temp Limit Setpoint.
Sensor Error LED:
This LED lights red whenever the sensor voltage is either
greater than 5V or less than 0.2V. This refers only to the feedback sensor, not the
auxiliary sensor. This condition can occur if the impedance of the sensor is too
high or too low, or if the sensor is disconnected from the Output Connector. The
output current is automatically switched off when this error occurs.
Output Section:
Output Enable Button:
This button enables and disables the thermoelectric
current source output. When the output is enabled, the current is determined by
the load conditions. If the output is disabled, the output current is brought to a very
low standby current. If an error occurs that shuts off the output, the button must be
pressed once to clear the error and again to enable the current.
Output On LED:
This LED lights green whenever the output is enabled and current
flows through the TE module.
Adjust Potentiometer:
This ten-turn linear potentiometer is provided to adjust the
Temperature Setpoint. It can adjust beyond the displayed temperature. See
page 33 (Pins 14 & 15 on the Analog Interface Connector -Temperature Monitor)
for more information.
Limit Current LED:
This LED lights red whenever the output thermoelectric current
is limited to the adjustment set by the Limit Current Trimpot. This condition will
remain until the current required to achieve temperature falls below the Limit
Current Trimpot setting. This condition does not create an error to shut the output
off.
Limit Current Trimpot:
This trimpot adjusts the thermoelectric Limit Current
Setpoint. Adjusting the trimpot clockwise increases the Limit Current.
Beeper:
A single “beep” indicates when the output is turned on or off.
Display Section:
3 ½ Digit Display:
This can be used to display the actual sensor temperature,
setpoint temperature, auxiliary zone temperature, output thermoelectric current,
thermoelectric limit current, and output thermoelectric voltage.
Display Select Switch:
The position of this switch determines what value is
displayed on the 3 ½ digit LED display.
100
µµ
A, 10
µµ
A, and LINEAR: To display the resistance or temperature of the
sensor, the switch is set to one of these three positions. The first two positions
are for thermistors and RTDs. The switch position should be coordinated with
the reference current setting on the Configuration Switch on the rear panel.
The third position (LINEAR) is used for IC Sensors such as the LM335 or
AD590. To read the auxiliary sensor resistance, set the position to
100
µµ
A and
hold in the Aux Sensor Button. To display the setpoint, set the position to the
one appropriate to the sensor being used and hold in the Display Set Button.
TE I: This position displays the amount of current being sourced through the
thermoelectric.
LIMIT I: This position displays the Limit Current Setpoint as set by the Limit
Current Trimpot.
TE V: This position displays the voltage across the thermoelectric.