Watlow Series 985 - Manual (Page 15)

Input Options “2” & " 3 " RTD - 2 Wire
Terminals 12 - 14
ModeI#98 _ A - 2 _ _0-0000
98_A-3_ _0-0000
Jumper#l3to#l4
Input Options “2” & " 3 " RTD - 3 Wire
Terminals 12 - 14
Model# 98_A-2_ _ 0-0000
98_A-3_ _0-0000
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.
.
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-
NOTE:
Long lead lengths create electrical resistance. There will be
a
1° approximate
input error for every 1ohm of lead length resistance when using a two wire RTD.
That resistance, when added to the resistance of the RTD element, can result in
erroneous input to the instrument. To overcome this problem, use
a
three wire
RTD sensor, which compensates for lead length resistance. When extension wire
is used for a three wire RTD, all three extension wires must have the same
electrical resistance. (i.e. same gauge, copper stranded).
Figure 12 -
Input Options "2" &
“3”, RTD (2 wire)
Sensor Wiring.
Figure 13 -
Input Options “2’ &
‘*3”, RTD (3 wire)
Sensor Wiring.
Install and Wire, Chapter 2
WATLOW Series 980/985 User's Manual 15