6.22 Wire fail detection
If it is necessary to supervise the sensors/wires connected to the multi-inputs and analogue inputs, then it is
possible to enable the wire break function for each input. If the measured value on the input is outside the
normal dynamic area of the input, it will be detected as if the wire has made a short-circuit or a break. An
alarm with a configurable fail class will be activated.
Input Wire failure area Normal range Wire failure area
4 to 20 mA < 3 mA 4 to 20 mA > 21 mA
Pt1000 < 823 ohm - > 1941 ohm
RMI Oil, type 1 < 1.0 ohm - > 195.0 ohm
RMI Oil, type 2 < 1.0 ohm - > 195.0 ohm
RMI Temp, type 1 < 4.0 ohm - > 488.0 ohm
RMI Temp, type 2 < 4.0 ohm - > 488.0 ohm
RMI Temp, type 3 < 0.6 ohm - > 97.0 ohm
RMI Fuel, type 1 < 0.6 ohm - > 97.0 ohm
RMI Fuel, type 2 < 1.0 ohm - > 195.0 ohm
RMI configurable < lowest resistance - > highest resistance
Level switch Only active if the switch is open
Principle
The illustration below shows that when the wire of the input breaks, the measured value will drop to zero.
Then the alarm will occur.
Wire failure
Wire failure
Wire break
Lower failure
limit
Upper failure
limit
Input signal
(mA, °C,b, %)
t
6.23 Input function selection
Digital input alarms can be configured with a possibility to select when the alarms are to be activated. The
possible selections of the input function are normally open or normally closed.
The drawing below illustrates a digital input used as an alarm input.
AGC 100 Designer's Reference Handbook
4189340766 UK
Additional functions
DEIF A/S Page 86 of 152
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