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Siemens AG ⋅ May 1998
2.3.8 Operational and fault events
The 7SS52 supplies detailed data for the analysis of
faults as well as for operational events.
Up to 99 operational events and 40 fault events are
stored in a rotating buffer in the master unit.
D Operational events
Switching operations, (e.g. isolator switching),
protection status indications (e.g. start of cyclic
test), isolator status irregularities (running time,
auxiliary voltage failure, etc.) and other monitoring
functions belong to this group of events.
D Fault events
Trip signals in the event of busbar short-circuits,
circuit-breaker failure and transfer trip belong to
this group of events.
2.3.9 Self-monitoring
Hardware and software are continuously monitored;
irregularities are recognised instantly and annunĆ
ciated.
High security and availability are achieved by the conĆ
tinuous monitoring of:
1. the isolator status,
2. the trip circuits,
3. the measured currents,
4. the measured value transformation,
5. all supply voltages,
6. the program memories,
7. the program processing.
For diagnosis purposes in the event of device failures,
a dedicated data memory is available in the master
unit.
The busbar and breaker failure protection 7SS52 as a
system consists of the components
D master unit
D bay units
D data links (fibre-optical cables).
The master unit can be delivered in a SIPAC 19'' subĆ
rack for cubicle mounting or in a casing for surface /
wall-mounting. On account of the modular design,
different fitting variants can be coordinated with the
station configuration. The bay units are built into a
7XP20 casing for cubicle mounting or surface mounĆ
ting.
Prefabricated glas-fibre optical cables (62,5/125m)
with double-end FSMA plug connectors are used for
the data exchange. They are suitable for outdoor inĆ
stallation and can be delivered with specific anti-roĆ
dent protection.
Indoor cables may be used for centralized configuraĆ
tion of the bay units.
2.4.1 Bay units
2.4.1.1 7SS521x-5DA00-xAA0 for panel surface
mounting
For the variant "surface mounting" the bay units are
delivered in casings type 7XP2040-1.
The casing is completely metal-closed with a removaĆ
ble front cover with acrylic window. The integrated
button can be used for reset of the LEDs while the
front cover is fitted.
Earthing screws are at the left side of the casing.
The heavy-duty current terminals automatically short-
circuit the current transformer when the module is
withdrawn.
All signals including the auxiliary voltage are connecĆ
ted to double-level terminals. The device has 28 conĆ
nection terminals at the bottom side and 50 more terĆ
minals at the top side. In each level the terminals are
numbered from left to right.
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