Electrical Protection Systems
Electrical power system operates at various voltage levels from 415 V to 400 kV or even more. Electrical apparatus used may be enclosed (e.g. motors) or placed in open (e.g. transmission lines). All such equipment undergo abnormalities in their life time due to various reasons.
For example, a worn out bearing may cause overloading of a motor. A tree falling or touching an overhead line may cause a fault.
A lightning strike (classiﬁed as an act of God!) can cause insulation failure. Pollution may result in degradation in performance of insulators which may lead to breakdown. Under frequency or over frequency of a generator may result in mechanical damage to it’s turbine requiring tripping of an alternator.
Even othervise, low frequency operation will reduce the life of a turbine and hence it should be avoided.
Whenever human security is sacrificed or there exists possibility of equipment damage, it is necessary to isolate and de-energize the equipment.
Designing electrical equipment from safety perspective is also a crucial design issue which will not be addressed here.
To conclude, every electrical equipment has to be monitored to protect it and provide human safety under abnormal operating conditions. This job is assigned to electrical protection systems. It encompasses apparatus protection and system protection.
Here, on this page you will find 10+ ABB’s power system protection practices that can be of great help to protection engineers and others. Guides are free to download.