Protection Application Handbook (англ. яз.)
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SUB-DIVIDED PROTECTION SYSTEMS. HOW?
Sub-divided Systems
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avoided. The simple reason is that security is always lost and the
total reliability is dependent on both security and dependability.
Most unwanted trippings in sub-stations are proven to be depen-
dent of human mistakes. A basic principle at protection system
design should thus be to design the protection system simplest
possible but fulfilling the single failure criteria.
The design shall be such that human mistakes are avoided and
this includes mistakes during all stages of a project from basic
design where guide-lines are set, through detailed design stage,
erection, commissioning and maintenance.
It must be remembered that the life-time total cost of a plant is to
a big part including cost for service and maintenance and also
cost for availability. The cost of an unnecessary tripping can be
much higher than the initial cost increase to include some extra
equipment. Unnecessary equipment and complications should
thus be avoided.
SUB-DIVIDED PROTECTION SYSTEMS. HOW?
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BA THS / BU Transmission Systems and Substations
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2.6 CONCLUSION
Means to ensure a reliable redundant protection system are:
- Limit the mixing of equipment from different objects or from different
sub-systems in the same panel. When mixing, clearly label the equip-
ment on the front and also within the panel to indicate object or sub-sys-
tem belonging.
- A standardized terminal numbering system simplifies design and mini-
mizes mistakes at panel design and erection and commissioning.
- Avoid exchange of information between sub-systems as far as possible.
When signals between the sub-systems are required, indicate where
these circuits are located both on the front and inside the panel. A sep-
arate terminal group should be used.
- Keep design as simple as possible. Do not include extra equipment to
cover more “if's”. Extra equipment can increase dependability but will al-
ways mean a reduced security and thus a reduced reliability.
Appendix 1 A redundant battery system Block diagram
SUB-DIVIDED PROTECTION SYSTEMS. HOW?
Sub-divided Systems
for worldwide cooperation
353
BA THS / BU Transmission Systems and Substations
LEC Support Programme
SUB-DIVIDED PROTECTION SYSTEMS. HOW?
354
BA THS / BU Transmission Systems and Substations
LEC Support Programme
We hope you have found the content of interest and of use for your work.
The protection application is an area where primary system knowledge is of
vital importance and where the technology of the secondary equipment is
going through a very fast change with micro-processor technology giving
many advantages such as:
- Self Supervision minimizing your maintenance
- Internal intelligence allowing improved functions for service values check-
ing, event listing and disturbance recording which gives a much improved
reliability of the protection system if correctly used for post-fault analysis.
- Few spare parts and thus low spare part cost due to the hardware plat-
forms for each products where different software is provided to give the dif-
ferent functions.
- Improved protection functionality where the numerical technic with possi-
bilities to store pre-fault conditions etc. gives a possibility to improve the pro-
tection functions.
PROTECTION
APPLICATION HANDBOOK
BOOK No 6
Revision 0
ABB Transmission and Distribution Management Ltd
BA THS / BU Transmission Systems and Substations
P. O. Box 8131
CH - 8050 Zürich
Switzerland
BU TS / Global LEC Support
C/o ABB Switchgear AB
SE - 721 58 Västerås
Sweden
ReklamCenter AB (99244) Printed in Sweden, ABB Support 1999-06