Pre-commissioning tests and in-service checks of protection system
The pre-commissioning tests need to be carefully programmed so that they take place in a logical and efficient order, in order that no equipment is disturbed again during subsequent tests. Before starting the tests, it is essential to ensure that… Read more
Jun 14, 2017 | By Edvard Csanyi
Philosophy of a good relay protection settings for machines and plants
The objectives of the protection system are: to limit damage to people and to the plant, permit different service conditions, guarantee maximum service continuity for the plant not affected by faults and activate the automatisms provided. The protection relays are normally provided for different objectives… Read more
Jun 09, 2017 | By Edvard Csanyi
How backup protection is used to improve fault-clearing system in HV networks
All elements in the fault-clearing system do not always operate correctly. Protection relays may fail to operate or may operate unwantedly. Switching devices may fail to interrupt the fault current. Common practice is to use several protection systems operating in…...
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Jun 05, 2017 | By Edvard Csanyi
Three earthing fault typologies and connection of the CB poles in a DC network
In order to break a short-circuit current in a d.c. system, it is necessary to connect the circuit breaker (CB) poles in a suitable way. To carry out this operation, it’s necessary to know the earthing typology of the plant…. Read more
Jun 05, 2017 | By Edvard Csanyi
Twelve installation tips for implementing a good residual protection
All installations have an earth leakage current that is mainly due to the conductor’s capacitive leakage and to anti-parasitic or EMI filtering capacitors, for example class I equipment. The sum of these leakage currents may cause highly sensitive residual protection… Read more
Jun 02, 2017 | By Edvard Csanyi
Eight typical transformer protection schemes with correctly selected relays
This technical article shows application hints for typical transformer protection schemes where SIPROTEC 4 relays are used. Some of applications are small and large transformer infeed, dual infeed with single transformer, parallel incoming transformer feeders, and others like parallel incoming… Read more
May 31, 2017 | By Edvard Csanyi
Auto-reclose schemes for re-energising the line after a fault trip
Faults on overhead lines fall into one of three categories: transient, semi-permanent and permanent. 80-90% of faults on any overhead line network are transient in nature. The remaining 10%-20% of faults are either semi-permanent or permanent. Transient faults are commonly… Read more
May 15, 2017 | By Edvard Csanyi
Current sensors as the eyes of RCD and tips for their correct installation
All residual current devices are made up of at least two components. First component act as the eyes of RCD – sensors – must be able to supply an electrical signal which is useful when the sum of the currents flowing… Read more
May 12, 2017 | By Edvard Csanyi
Protection of capacitor banks by fuses during energization and operation
Stress specific to the protection of capacitor banks by fuses, which is addressed in IEC 60549, can be divided into two types: Stress during bank energization (the inrush current, which is very high, can cause the fuses to age or blow) and Stress… Read more
May 01, 2017 | By Edvard Csanyi
Why and where do internal faults happen in substation transformers
Transformers are subjected to many external electrical stresses from both upstream and downstream that can lead directly to internal fault(s). The consequences of any failure can be very great in terms of damage as well as in terms of operating… Read more
Apr 28, 2017 | By Edvard Csanyi
The most frequent errors in specifying current transformers (CTs)
Current transformers (CTs) form an essential link within the protection chain of electrical networks. Their specification, even if it is handled by specialists, often includes errors and is insufficiently optimized. This often leads to technological impossibilities, operating delays, extra costs,… Read more
Apr 24, 2017 | By Edvard Csanyi
Thumb rules for surge arrester installation in different earthing systems
A variety of documents deal with the subject of surge arrester installation: for example in France, standard NF C 15-531 focuses on the installation rules of LV surge arresters, and standard NF C 15-100 covers all the LV electrical installations…. Read more
Apr 17, 2017 | By Edvard Csanyi
Circuit breaker selections for low voltage installation (with discrimination)
The LV installation which forms the subject of this study is shown in figure 1 above. This study includes discrimination and coordination of protection between the LV equipment and the protection located upstream of each MV/LV power supply transformer. The… Read more
Apr 14, 2017 | By Edvard Csanyi
Six network operating conditions under which ferroresonance can occur
Due to the multitude of various sources of capacitances and non-linear inductances in a real power network and the wide range of operating conditions, configurations under which ferroresonance can occur are endless. Experience has, however, made it possible to list… Read more
Apr 12, 2017 | By Edvard Csanyi
8 essential relay operating principles of catching faults
In general, as faults (short circuits) occur, currents increase in magnitude, and voltages go down. Besides these magnitude changes of the AC quantities, other changes may occur in one or more of the following parameters: phase angles of current and… Read more
Apr 10, 2017 | By Edvard Csanyi
