SEM104TC Datasheet, PDF (4/8 Pages) List of Unclassifed Manufacturers – SEM104 SERIES

4.0 RANGES
This transmitter is normally supplied in one of six standard ranges. Other ranges can be supplied at time
of order but with the aid of suitable equipment, the user can re-range the transmitter. On board links allow
the transmitter to be re-ranged to operate over most common industrial and commercial ranges. Due to
the nature of this transmitter, changes in span range affect both (4 and 20) mA calibration points. Ranging
the transmitter is very much simplified if calculations are based on the true zero of the transmitter, i.e.
the temperature at which the output would in theory be at 0 mA.
To verify that the transmitter will operate over the range you require, please follow the simple procedure
listed overleaf, calculating the SPAN and TRUE-ZERO temperatures for your range. Then ensure these
temperatures fall into one of the bands for SPAN and TRUE-ZERO listed in the tables overleaf. From the
tables select the links you need to make, solder blob them and then follow the calibration procedure to
trim the transmitter to the range you require.
NOTE : TRUE-ZERO is the temperature at which theoretical zero current would flow.
WARNING!
Re-ranging requires the soldering of small links located on a pcb, housed inside the
transmitter. The operator must be experienced in soldering and un-soldering
techniques on small PCB, or damage may occur to both PCB and enclosure. If in
doubt please state the required range at the time of order, to allow the factory to
calibrate for you. It is the users responsibility to ensure that no damage occurs due
to lack of care during this re-ranging procedure.
RE-RANGING AND CALIBRATION PROCEDURE
Before you start you will need the following equipment and information:
Resistance box; accuracy ± 0.01 Ω or better to simulate Pt100
DC milliamp meter (Digital); accuracy 0.05 % on (0 to 20) mA range.
Power supply; 24 VDC 30 mA minimum output current.
Suitable wires together with a trim tool and the Pt100 equivalent resistance values for the range
limits you require to set, i.e. the 4 mA and 20 mA calibration points.
STEP 1.
STEP 2.
STEP 3.
STEP 4.
Decide on the range you require,
Let;
Th = Required Temperature @ 20 mA Output
Tlo = Required Temperature @ 4 mA Output
Calculate SPAN
SPAN = Th - Tlo
Calculate TRUE-ZERO
TRUE-ZERO = Tlo - (SPAN/4)
Look up your SPAN and TRUE-ZERO temperature in the tables overleaf, and note the
links that need to be made. Then using a soldering iron, blob the links on the PCB
mounted inside the enclosure. Ensure any non called up links, soldered for a previous
range, are open circuited by removing the solder blob. Note you will need to remove
the enclosure base to gain access to the links. There are eight links in total, (A, B, C, D)
affect SPAN, and (W, X, Y, Z) affect TRUE-ZERO.
Page 5
TABLE 1 SPAN LINKS GROUP A, B, C + D
SPAN ºC
22 to 37
37 to 52
52 to 75
75 to 140
140 to 215
215 to 500
SOLDER LINKS
D
B, C
C
A, B
B
A
TABLE 2 TRUE ZERO LINKS, GROUP W, X , Y + Z
TRUE-ZERO ºC
-180 to -166
-166 to -147
-147 to -127
-127 to -108
-108 to -88
-88 to -69
-69 to -49
-49 to -35
-35 to -21
-21 to -1
-1 to 18
18 to 38
38 to 57
57 to 77
77 to 96
96 to 100
SOLDER LINKS
W, X, Y, Z
W, X, Y
W, X, Z
W, X
W, Y, Z
W, Y
W ,Z
W
X, Y, Z
X, Y
X, Z
X
Y, Z
Y
Z
-
Page 6
CD
AB
Z
Y
X
W