Functions
144
7SS52 V4 Manual
C53000-G1176-C182-3
5.5.1.7
Cyclic Test
Central unit
As part of the self-diagnostics, the protection functionality is checked on the basis of
the isolator replica. The cyclic test in faultless operation includes the unbalancing of a
current of a connected bay unit. The reaction of the bay unit is monitored.
As this test is treated like a real fault and uses the same transmission links for meas-
ured values and TRIP commands, it yields utmost security and reliability.
This test does not influence the protection functions.
The test is performed only if there is no pickup of the protection.
On detecting a failure, the identical test routine is repeated twice. After this a reset is
performed.
If the fault remains, the device will switch into monitoring mode.
Read out the fault buffer of the central unit and contact the manufacturer.
Bay unit
In the bay units, the trip command circuits are monitored additionally.
The following alarms may come up:
•
Group alarm: “
Flt autotest M
” (
FNo. 10429/CU
)
•
Single alarm: “
Flt aut $00
“ (
FNo. 176.1190/CU
)
The following indications provide more detailed information on the bay unit con-
cerned.
"
Relay control circuit flt.,trip possib
.
" (
FNo. 7689/BU
)
"
Relay1 control circuit flt.,no trip pos
" (
FNo. 7691/BU
)
"
Relay2 control circuit flt.,no trip pos
" (
FNo. 7692/BU
)
"
Relay3 control circuit flt.,no trip pos
" (
FNo. 7693/BU
)
"
Relay4 control circuit flt.,no trip pos
" (
FNo. 7694/BU
)
"
Relay5 control circuit flt.,no trip pos
" (
FNo. 7695/BU
)
With the alarm "
Relay control circuit flt., trip possib.
" (
FNo. 7689/
BU
) operation is still possible with reduced safety.
With the alarm "
Relay1 control circuit flt., no trip pos
" (
FNo. 7691/
BU ... 7695/BU
) no tripping is possible anymore.
You should replace the bay unit concerned.
5.5.1.8
Supervision of External Current Transformer Circuits
Interruptions or short circuits in the secondary circuits of the main current transform-
ers, as well as errors in the connections or in the configuration of the busbar protec-
tion, are systematically detected and reported by the system. It evaluates for this pur-
pose the differential currents which are formed in the protection processor modules
ZPS-BSZ1 to ZPS-BSZ3.
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