WIKA TR31 - Handbuch (Seite 21)

GB
WIKA operating instructions models TR31-3, TR31-K
14096788.01 07/2014 GB/D
21
6. Commissioning, operation
6.3 Behaviour of the electrical output signal 4 ... 20 mA
■ Sensor break and short-circuit
Sensor break or short-circuit are signalled after positive detection
(after approx. 1 second). If this fault condition has been caused by
a malfunction, then a relevant measurement signal must exist for
approx. 1 second in order to return to measuring mode. From the time
of the error detection up to the fault signal, the last relevant measured
value will be delivered on the current loop.
Therefore, in the event of a “true” sensor break or short-circuit, this
is also signalled permanently. In the event of a “false” sensor break
or short-circuit, the transmitter has the possibility of reverting to
measuring mode.
■ Medium temperature outside the span
If the media temperature configured in the transmitter exceeds
the span, the transmitter will operate in a linear fashion within the
following limits: 3.8 mA (MRS); 20.5 mA (MRE). If these limits are
exceeded, then an error will be signalled.
0 10 24 30 36
1083
833
583
Load diagram
The permissible load depends on the loop supply voltage. For
communication with the instrument with programming unit PU-448, a
max. load of 350 Ω is admissible.
Voltage U
B
in V
Load R
A
in
Ω