Publicité
Les langues disponibles
Les langues disponibles
Process transmitter
Connection between switch threshold and reset threshold
on
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
group
between the start value MW
interval. If the calculated value is larger than the value set up in
SETP
again once the value has dropped below that set up in
The direction of the difference (rising or falling) is set by the
prefix. A new value is calculated every second (moving interval).
Example:
In menu group
switch on threshold value is set in
the reset value in
in menu group
In this example the relay is deactivated when the increase in
filling (MW
relay is only powered up again when the lowering of the level
has reached a value of 2/time unit.
Operation of the alarm feature
If the parameter in
as a system alarm relay. The relay is only deactivated in an unit
fault condition, this can be:
- Cable open circuit as well as short circuit on 2-wire
transmitters
- Sensor fault on a 2-wire transmitter
- Cable open circuit on RT or thermocouples
- Certain hardware and software faults
(see fault finding)
62
TRD
(trend monitor):
in address
PARAM
then the relay is deactivated. The relay is powered up
Measurement value
Relay deactivated (no power), yellow LE off
À
The filling height is monitored for its rate of change.
address
LIM
RESP
PARAM
-MW
) has exceeded a value of 3/time unit. The
E
A
MODE
. The calculation is the difference
TRDT
and the end value MW
A
is set to parameter
MODE
and has the value
SETP
is set to
. The time cycle tm is set up
-2
in address
.
TRDT
ALARM
:
is set to
, then the relay operates
ALARM
<3.6mA or >21mA)
of the
E
.
RESP
t
. The
TRD
,
3
Publicité
