Endress+Hauser RMA 422 Mise En Service page 59

Dependence between switch threshold and
MIN
hysteresis on
MAX MAX-
/ (maximum safety):
On minimum safety a set point infringement remains active as
long as the measured signal is smaller than the switch
threshold plus hysteresis (
the value of the switch threshold minus hysteresis (
HYST
).
Measurement
MIN
SETP
Relay deactivated (no power), yellow LED
MIN
On settings and
relay also de-actives on a fault condition (
Connection between switch threshold and reset threshold
TRD TRD-
on / (trend monitor):
The trend feature has the task of monitoring the change of the
input signal over a specific time span. The time base over
which the signal is to be monitored can be set up in menu
PARAM
group address
between the start value MW
interval. If the calculated value is larger than the value set up
SETP
in then the relay is deactivated. The relay is powered up
again once the value has dropped below that set up in
The direction of the difference (rising or falling) is set up by
the prefix. A new value is calculated every second (moving
interval).
Measurement value
Relay deactivated (no power), yellow LED off
MIN-
/ (minimum safety) and
SETP HYST
+
HYST
MAX
in addition to the alarm condition the
TRDT
. The calculation is the difference
and the end value MW
A
), on maximum safety
SETP
-
Measurement
MIN
SETP
ALARM
).
of the
E
RESP
Process transmitter
HYST
.
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