68
c
HAPTER
4:
Operation
Model 350 Temperature Controller
The Current Reversal parameter defaults to On anytime the Sensor Type parameter is
changed to PTC RTD or NTC RTD.
Menu Navigation:
Input Setup
Q
Input
(A, B, C, or D)
Q
Current Reversal
Q
(Off or On)
Default: On
Interface Command:
INTYPE
4.4.5 Thermocouple
Sensor Input Setup
(Model 3060 Only)
When a Model 3060 Thermocouple option is installed in the Model 350, a setting of
Thermocouple becomes available under the Sensor Type parameter in the Input
Setup menu. The standard RTD sensor inputs can still be used when the Thermocou-
ple option is installed, but the Thermocouple and standard inputs cannot be used
simultaneously. Refer to section 7.4.2 to install the Model 30603060.
Thermocouples include a variety of commercial (such as E, K, T) and specialty types
such as cryogenic (Chromel–AuFe). Standard curves are included in the Model 350 for
the types listed in TABLE 4-7. Other types can be used as long as an appropriate tem-
perature response curve is loaded as a user curve. Representative thermocouple
specifications are given in TABLE 1-3. The Model 350 provides one thermocouple
range and no excitation because thermocouples do not require it. Internal room tem-
perature compensation is included for convenience (section 4.4.5.2) and should be
calibrated before use. Room temperature compensation is enabled by default, but
can be turned off if external compensation is being used.
Menu Navigation:
Input Setup
Q
Input
(C or D)
Q
Sensor Type
Q
Thermocouple
Interface Command:
INTYPE
4.4.5.1 Internal Room Temperature Compensation
Room-temperature compensation is required to give accurate temperature measure-
ments with thermocouple sensors. It corrects for the temperature difference
between the instrument thermal block and the curve normalization temperature of
0 °C. An external ice bath is the most accurate form of compensation, but is often
inconvenient. The Model 350 has internal room-temperature compensation that is
adequate for most applications. You can turn internal compensation on or off. It oper-
ates with any thermocouple type that has an appropriate temperature response
curve loaded. Room-temperature compensation is not meaningful for sensor units
measurements.
Room temperature compensation should be calibrated as part of every installation
Menu Navigation:
Input Setup
Q
Input
(C or D)
Q
Room Compensation
Q
(Off or On)
Default: On
Interface Command:
INTYPE
4.4.5.2 Internal Room Temperature Compensation Calibration Procedure
Factory calibration of the instrument is accurate to within approximately ±1 K. Differ-
ences in thermocouple wire and installation technique create errors greater than the
instrument errors. To achieve the best accuracy, calibrate with the thermocouple
actually being used, because it eliminates most sources of error. If that is not possible,
use a thermocouple made from the same wire.
It is best practice to use the same material for thermocouple wires; if it is at all possible, it
is also best to avoid splices. When splices are necessary, continue the splice with the same
type of material.
Summary of Contents for 350
Page 4: ...Model 350 Temperature Controller ...
Page 6: ......
Page 14: ...Model 350 Temperature Controller ...
Page 28: ...14 cHAPTER 1 Introduction Model 350 Temperature Controller ...
Page 53: ...Examples of PID control 2 13 4 ManualOutput 39 www lakeshore com FIGURE 2 4 ...
Page 58: ...44 cHAPTER 2 Cooling System Design and Temperature Control Model 350 Temperature Controller ...
Page 118: ...104 cHAPTER 5 Advanced Operation Model 350 Temperature Controller ...
Page 178: ...164 cHAPTER 7 Options and Accessories Model 350 Temperature Controller ...
Page 192: ...178 cHAPTER 8 Service Model 350 Temperature Controller ...