30
+
-
+
-
+
+
-
-
Rin lin COM SCN
5.4 Probe wiring
The maximum cable length for all transducers is 100 m (328 ft).
Note: It is essential to select the correct sensitivity on the PA20 preamplifier,
(see the PA20 Installation and Maintenance Instructions for details).
Back
Front
Connect to
a clean earth
local in the
panel
Notes:
1. E = Functional earth - Connect these pins to a clean earth local to the panel.
2. Do not connect terminal 54 to any other earth.
3. Ensure that the resistance from probe body to the pipework / boilershell is less than 1 Ohm.
Fig. 16 Signal circuit (view from the top)
50 51 52 53
70 71 72 73 74
4-20 mA output
4-20 mA
valve positioner
4-20 mA
water
flowmeter
1 kohm
feedback
potentiometer
valve motor drive
Capacitance probe
(see PA20 IMI for
sensitivity selection)
1 2
54 55 56 57 58 59 60 61 62
Feedback potentiometer /
water meter
+24V Vin lin COM SCN E
Level input (s)
75 76 77 78 90 91 92 93 94 95 96 97 98
4-20 mA
output
4-20 mA
input
See RS485 / MODBUS wiring notes
Screens
4-20 mA
steam meter
0-20 mA
or 4-20 mA
output display
(0 -100%)
Screens
Open
Close
Connect to
a clean earth
local to the
panel
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