Wavelength Electronics LFI-3751, User Manual

Page: 56 / 132

56
P ACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
AMPS
P ACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
AMPS
Negative LIM I
Positive LIM I
To protect the thermoelectric or resistive heater, positive and negative limit
currents can be set below the damage threshold.
•
Rotate the Display Select Switch to LIM I ( Shift Button OFF) . Current (in
Amps) will be displayed. The positive limit will alternate with the negative
limit. Rotating the
Digi-Pot Adjust Knob clockwise makes the Positive
LIM I more positive. Rotating the Digi-Pot Adjust Knob counter-clockwise
makes the Negative LIM I more negative.
•
To operate a Resistive Heater, set the Positive Limit to 0.00 Amps.
•
The limit settings will not be updated until the Digi-Pot stops moving.
•
When the output is current limited, TE I will be within
±
50 mA of the
limit setting.
•
LIM I settings are saved in non-volatile memory.
•
When the setpoint and actual temperature are different, the LFI-3751
drives current to the thermoelectric or resistive heater until the load
approaches the setpoint temperature. Sometimes the output current is
driven up to the limit current settings (indicated by the
LIM I LED fl ashing).
A lower Limit Current will increase the settling time since less power is
delivered to the thermoelectric (or resistive heater).
•
The LIM I LED in the Status Section fl ashes when the maximum current
(positive or negative) is being sourced to the thermoelectric or resistive
heater.
•
RS-232 Command: [LIM I POSITIVE], [LIM I NEGATIVE]
Chapter 2 - Front Panel Operation
Setting Limit Currents
Setting Limit Currents
Display Resolution:
Positive LIM I
Negative LIM I 0.00
-5.00
to
to +5.00 Amps
0.00 Amps
LIMIT I
LIM I LED fl ashes when
Positive or Negative Limit is
reached
Display Limit Currents
P ACT T
LIM I
AUX T
TE V
SET T
TE I
B
C
I
A
D
Default Limit Currents
= 1.00 Amp
= -1.00 Amp
Positive LIM I
[LIM I POSITIVE]
Negative LIM I
[LIM I NEGATIVE]