'(& )( )'& &) ( &!& ")& &$(( $# Ć %&( $# #)" &&#$
7 - 2
Siemens AG ⋅ May 1998
Disturbances of digital protection devices are in most
cases caused by component failures. Practical expeĆ
rience also shows that ambiental conditions (e.g.
short electromagnetic interference beyond the values
guaranteed by the manufacturer) may in few cases
initiate failure alarm.
Continuous failures in the protection system or its
components are indicated at the master unit by chanĆ
ging the operations indication from LED green, to the
red LED "failure" and reset of the alarm relay "device
failure". Additionally the protection system is blocked
in order to avoid overfunction.
The disturbance can be caused by:
1. Failures in the master unit
(Failure or defect in the auxiliary voltage supply,
module failure)
2. Failures in one of the connected bay units (interĆ
ruption of power supply, defective measuring cirĆ
cuit, module failure)
3. Interruption of the communication link to one of
the bay units
(defective transmission or reception modules, inĆ
terrupted FO link, increased number of transmisĆ
sion errors)
Guided by the various failure causes, a systematical
analysis has to be carried out. The user is herewith
supported by the protection system's diagnostic inforĆ
mation:
1. Master unit
- operational event buffer
- fault event buffer
- operational events marshalled to LEDs (refer to
chapter 6.2.7)
- LED indications on the modules
2. Bay unit
- operational events marshalled to LEDs (refer to
chapter 6.4.2.4)
The master unit's operational events provide first
hand information about the cause of a registered deĆ
vice failure. If operational events which have been
marshalled to LEDs are missing, then the operational
event buffer in the master unit has to be interrogated
(). The user gets information about
D auxiliary voltage failure,
D pick-up of the differential current supervision,
D errors in the measured value supervision of the
bay units and
D failure detection by the cyclic test.
Detected failures in the bay unit are indicated with
their bay number in order to locate the failure.
Thus the failure can further be located locally in the
bay. Operational events which support identification
of a failure are e.g.:
D Disturbance of the power supply
D Failure detection by the measured value superviĆ
sion.
To Next Page
Loading...
Need help?
General
