Metek EX1200A SERIES, User Manual

Page: 99 / 163

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EX1200A Triggering 99
R
0
= nominal resistance of RTD (resistance at 0 °C)
T = temperature in °C
A = α[1+ (δ/100)]
B = -αδ/1 x 10
4
C = -αβ/1 x 10
8
)
For the RTD’s with built-in support, the following Callendar-Van Dusen RTD parameters are
used:
RTD Type Standard
α β δ
R
0
PT100 ITS-90 0.003850 0.10863 1.49990 100 Ω
D100 ITS-90 0.003920 0.10630 1.49710 100 Ω
F100 ITS-90 0.003900 0.11000 1.49589 100 Ω
PT385 IPTS-68 0.003850 0.11100 1.50700 385 Ω
PT3916 IPTS-68 0.003916 0.11600 1.50594 3916 Ω
2-Wire Measurement Connections
A 2-wire RTD measurement is connected in the same manner as a 2-wire resistance measurement.
The HI and LO terminals of the DMM are connected to the RTD’s two terminals (no polarity
restrictions).
DMM Front Panel
Sense HI
Input HI
Input LO
Sense LO
RTD
F
IGURE
4-15: RTD 2-W
IRE
C
ONNECTION TO
DMM F
RONT
P
ANEL
When using the DMM bus backplane through a switch multiplexer, as shown in Figure 4-16,
observe the common practices introduced in the voltage and resistance measurement discussions
above. Shielding greatly reduces the effect of external interferences/noises. It should also be noted
that the shields should only be connected to ground at one end of the cable and not both.