User manual - METER SRT-73
Figure 4.9. Example of OC-type outputs connection
Temperature sensor can be connected to the device in typical 4-wire circuit (Figure 4.10a) or
3-wire circuit (Figure 4.10b). Due to precision of measurement 4-wire circuit is recommended.
If 2 wire circuit is used it is recommended to connect sensor accordingly to Figure
4.10c
.
(4-wires circuit with shorted pins 6+7 and 8+9). In this case, the resistance of
wires should be as small as possible, to avoid of measurement errors. Measured
value can be corrected (constant correction) using
toFS
parameter from menu
inPt
. Due to low precision 2-wire connection is not recommended.
When 4-wires or 2-wires connection is used, the resistance of particular wires (Ra ÷ Rd)
CAN BE DIFFERENT
. When 3-wires connection is used, the resistance of particular wires
(Ra ÷ Rd)
MUST BE IDENTICAL
to enable proper compensation of it's resistance. The
resistance of particular wire
should not be greater than 20
Ω
Ω
.
a)
b)
c)
Figure 4.10. Connection of sensors:
a) 4-wires circuit; b) 3-wires circuit; c) 2-wires circuit;
The connection circuit should not be changed while unit is powered. Every change
of connection while the unit is powered causes measurement errors by several
seconds after change.
12
16 17
Uo
3 4
OC1
- +
+ -
+
voltage input
24 V
-
Logic controller
16 17
Uo
3 4
OC1
- +
+ -
R
2k2
LED 10 mA
Pt100
Ra
Rb
Rc
Rd
Ra, Rb, Rc, Rd can be different
6 7 8 9
Pt100
Rb
Rc
Rd
7
9
8
6
Rb = Rc = Rd
n.c.
Pt100
Rb
Rc
7 8
6
9
Rb, Rc can be different
i
i
Summary of Contents for SRT-73
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