Functional description
Page 14 of 72
MSM-USM2G-BA-UK-004
3.6.3 Mirroring of single alarms
Fig. 3.4: Application example for mirroring
For large plant areas and complex processes, the following are often performed at central points
or in control rooms important individual alarms from the field are required. In classic systems, 1:1
relays are used here, which means a high wiring effort. With USM fault indication systems, this effort
can be greatly reduced. 32 USM field stations can send individual alarms to a central USM or another
USM field station via a network connection (copper or fibre optic) and thus mirror them. The mirrored
alarms do not have to be individually wired or acknowledged "at the mirror", but are always in the
status of the alarm of the triggering USM.
3.6.4 Protocol IEC 61850 (optional)
Information from field and protection devices in automated switchgear is transmitted via the IEC 61850
protocol. In addition, various individual alarms are generated which - depending on the type of alarm -
must also be transmitted to the process control system or other devices at the field or station level.
With the aid of the optionally integrable IEC 61850 server, the fault indicators of the USM series take
on this "rag man" function. Individual alarms and, with the help of the optional analogue inputs,
measured values can be transmitted. Individual reports and datasets can be easily configured to
provide all relevant information on the alarm and device status. When creating the file, you can choose
between editions 1.0, 2.0 and 2.1 of the IEC standard. A license is required to use this interface.
The USM can monitor the IEC 61850 communication (e.g. from the control system to the USM). A
configurable time is monitored in which the communication partner must periodically report to the
USM. If the time is exceeded, a freely assignable digital input is activated. Furthermore, the USM can
also be configured to monitor third-party devices if these can operate as IEC 61850 masters.
