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PRESYS
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Instruments
2.3.2 - RTD Input
An RTD input device may be a 2-wire, 3-wire or 4-wire RTD. All types of
connection are shown in figure 7.
A 2-wire RTD is connected to terminals 1 and 3 when using input 1 and to
terminals 4 and 6 when using input 2 as shown in figure 7.
A 3-wire RTD is connected in the same way as explained for a 2-wire RTD,
adding the connection of the compensation wire to terminal 2 for input 1 and to
terminal 5 for input 2 as shown in figure 7.
Connect a 4-wire RTD as indicated for a 3-wire RTD and keep its forth wire
disconnected. See figure 7.
With a 3-wire RTD one gets a better precision than with a 2-wire RTD.
Use wires of same material, gauge and length on all 3 terminals of each
channel for compensating resistance. The maximum resistance of each connection
wire must be 10 Ω. Use 18 AWG wire (minimum) for distances up to 50 m and 16
AWG for distances greater than 50 m.
RTD
Note 1
6 5
4
3
Channel 2
Channel 1
2-WIRE
RTD
Note 1
6 5
4
3
Channel 2
Channel 1
2-WIRE
Note 1: Shield to be left unconnected at this end..
Note 1
2
1
6 5
Channel 2
Note 1
2
1
6 5
Channel 2
Figure 7 - RTD Input
DMY-2011, DMY-2035 and DMY-2036
GROUNDED
RTD
Note 1
4
3
2
1
Channel 1
3-WIRE
UNGROUNDED
RTD
Note 1
4
3
2
1
Channel 1
3-WIRE
RTD
NC
NC
6 5
4
3
2
1
Channel 2
Chanhel 1
4-WIRE
RTD
NC
NC
6 5
4
3
2
1
Channel 2
Channel 1
4-WIRE
Installation
Page 11
Note 1
Note 1
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