Limit Modules; Overview Of Limit Modules; Monitoring Of Current Saturation - Siemens SITRANS P300 Operating Instructions Manual

Operating functions via HART
7.21 Diagnostic functions
See also
Overview of simulation (Page 7-32)
7.21.5

Limit modules

7.21.5.1

Overview of limit modules

Description
The diagnostic functions of this device provide you with the option of monitoring measured
values in limits that can be configured. When the limits are violated, the device warns you via
HART communication or reports an analog fault current to a higher-level recipient.
7.21.5.2

Monitoring of current saturation

Description
You can use a simple limit module to monitor the current output in the saturation range. This
module is configured and activated via HART communication. For HART communication,
use a HART Communicator or PC software such as SIMATIC PDM. You need to configure
two time periods. The first time period specifies how long the current output is allowed to be
in saturation (response time) before an interrupt is triggered and the device outputs its set
fault current. The second time period (stop time) specifies the duration of the interrupt.
In the first example, the response time starts at time t
programmed saturation limit for the first time. At t
begins. The interrupt is revoked immediately as soon as the programmed stop time has
passed (t
In the second example, the duration of the current saturation is shorter than the response
time (t
In the third example, the current only exceeds the lower saturation limit for a short time. The
fault current is not switched off until after the end of the stop time (t
7-30
) and the current has gone below the saturation limit again.
3
, t ). In that case, the device does not go into "fault current" state.
1 2
, when the current reaches the
1
the response time ends and the stop time
2
).
3
SITRANS P300 with HART communication
Operating Instructions, 06/2005, A5E00359579-02