Correction of the Meas. Value and Compensation
10.2.7 Cold Junction Compensation
Cold junction compensation (CJ) for the thermocouples is normally performed
completely automatically. On this device, with 5 sockets, to ensure the highest
possible degree of accuracy - even in difficult thermal conditions (e.g. thermal
irradiation) the socket temperatures are acquired by means of two precision
Ntc sensors in measuring sockets M0 and M8 and then calculated by linear in-
terpolation. The mean cold junction temperature is displayed as an operating
parameter in the device configuration. (s.
It can be incorporated if necessary in measured data acquisition as a device
temperature with function channel "CJ" (s. 11.3.10) Instead of this form of cold
junction temperature measurement it is also possible to use an external mea-
suring sensor (Pt100 or NTC) in an isothermal block (see Manual, section
6.7.3); this must be positioned upstream from the thermocouples and "*J" must
have been programmed in the first two positions in the comments (s. 11.3.2).
For especially exacting requirements (e.g. for thermocouples for which there is
no connector with thermo-contacts or for large temperature differences caused
by thermal irradiation) there are special connectors available for cold junction
compensation each with its own integrated temperature sensor (ZA-9400-FSx).
These can be used for all thermocouple types; however, they require two mea-
suring channels. Having "#J" programmed in the first two positions in the com-
ments for the thermocouple ensures that the temperature sensor integrated in
the connector is indeed used for cold junction compensation.
10.3 Measuring point scans and Output
Measuring point scans can be used to acquire the measured values of all mea-
suring points at particular times, either manually or cyclically over a period of
time, which means to store or to record on printer or computer (s. man. 6.5).
For this purpose, the menu
Data logger
, e.g., is available:
10.3.1 Single Output / Storage of all
Measuring Points
Single manual measuring point scans for ac-
quiring the momentary measured values of all
active measuring points
(s.man. 6.5.1.1)
can be
triggered by the key
<MANU>
. If the true time of
day has to be indicated, it must first be set (s. 11.1.1). The output format can
be set in the function
Cycle Timer
(s. 10.3.2).
ALMEMO
®
2890-9
29
C © REC COM l© ©l R01 * ´´´´´´µµµµ¶
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
Time: 12:34:56 Date: 01.01.04
Cycle timer:
00:00:30 nS
Memory free:
508.3 kB
Number:
01-001 A
01: 244.5 °C
NiCr Temperatur » H º
7 Limit max:
250.0 °C
Maximum value:
245.7 °C
7 Limit min:
230.0 °C
Minimum value:
224.1 °C
START MANU M PRINT ESC
