Medium Voltage
Standard tripping schemes and trip circuit supervision schemes for MV switchgear
Medium voltage switchgear is used for switching medium voltage loads through associated control, measuring, protective and regulating equipment. This operation also involves considerable manual intervention which therefore necessitates the fulfilment of safety requirements laid down in International Standards. A variety… Read more
Oct 08, 2018 | By Edvard Csanyi
Protection
Short circuit phenomenon you should properly understand
A short circuit in an electrical circuit is a part of the circuit that for some reasons has become “shorter” than it should be. The current in an electrical circuit flows the easiest way and if two points in a… Read more
Oct 03, 2018 | By Edvard Csanyi
Medium Voltage
Coordination analysis for a typical 13 kV distribution feeder of several lines
A typical 13 kV feeder of several lines at a distribution substation is shown in Figure 1. This is supplied from a 115 kV line through a 15/20/25 MVA transformer protected by a high-side fuse. Only one of the four… Read more
Oct 01, 2018 | By Edvard Csanyi
Power Substation
MV/LV transformer protection against temperature rise, overloads, short-circuit & overvoltages
When selecting the type of transformer correctly electrical engineer needs to know its different electrical and thermal properties and the resistance to stresses due to faults or normal service of the transformer itself. This is crucial to know. The transformer… Read more
Sep 26, 2018 | By Edvard Csanyi
High Voltage
Busbar protection schemes for distribution substations
Busbars play an important role in power transmission and distribution. They are employed as a central distribution point for all feeders. In the case of a fault, current on the busbar becomes high, resulting to mechanical destruction which would affect… Read more
Sep 24, 2018 | By Edvard Csanyi
Electric Motor
How to know if you set the correct current on a motor thermal overload relay
The full-load current at a given voltage indicated on the nameplate is normative for setting the overload relay. Because of the variable voltages around the world, motors for pumps are made to be used at both 50 Hz and 60… Read more
Sep 19, 2018 | By Edvard Csanyi
Monitoring
Secondary equipment you should always consider when retrofitting existing HV substation
This approach assumes retrofitting and upgrading old substation secondary equipment such as intelligent electronic devices (IEDs), monitoring sensors, power apparatus, communication protocol and operating standards to improve the overall performance or reduce cost without disrupting the continuity of service. For… Read more
Sep 17, 2018 | By Edvard Csanyi
Protection
Relay settings and applying high-impedance differential busbar protection scheme
Most of HV busbar faults involve single-phase and earth, but faults may arise from many different causes. The number of faults that stand out is between phases clear of earth. In fact, a large proportion of busbar faults result from… Read more
Sep 12, 2018 | By Edvard Csanyi
Electric Motor
Earth fault protection of an AC motor in four different earthing systems
One of the most common faults to occur on a motor is a stator winding fault. Whatever the initial form of the fault (phase phase, etc.) or the cause (cyclic overheating, etc.), the presence of the surrounding metallic frame and… Read more
Sep 10, 2018 | By Edvard Csanyi
Power Substation
Applying CTs in protection schemes for transformers, generators, machines etc.
Various types of instrument transformers are currently in use on the basis of the varied applications of these devices. The construction aspects and sizing play an important role in the selection of proper types of both CTs and VTs. The… Read more
Sep 05, 2018 | By Edvard Csanyi
Power Substation
The zone selective interlocking logic of protection relays
This function significantly reduces the tripping time of the circuit breakers closest to the source. It can be used for zone selective interlocking (ZSI) in closed ring networks. It applies to the phase overcurrent 50/51, directional phase overcurrent 67, ground fault… Read more
Aug 27, 2018 | By Edvard Csanyi
Protection
The fundamentals of protection relay co-ordination and time/current grading principles
Transmission and distribution systems are exposed to overcurrent flow into their elements. In an electric power system, overcurrent or excess current is a situation where a larger than intended electric current exists through a conductor, leading to excessive generation of… Read more
Aug 13, 2018 | By Edvard Csanyi
Energy and Power
Generator earthing and stator earth fault protection
Generating unit is a pretty complex system made up of the generator stator winding, its transformer and unit transformer (if present), the rotor with its field winding and excitation system, and the prime mover with its associated auxiliaries. Many different… Read more
Aug 06, 2018 | By Edvard Csanyi
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Current and voltage digital transformation in a modern substation protection and automation
Developments in communication have done much to realize the digital substation, but to realize a full digital substation it is necessary to have everything in digital form. Whilst much substation protection, control, and automation technology has always been digital (trip…...
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Jul 25, 2018 | By Edvard Csanyi
Energy and Power
How to create a specific neutral earthing system within existing one (islanding)
Each neutral earthing system has advantages and disadvantages for the safety of property, electromagnetic compatibility or continuity of service. The main system must therefore be chosen according to these criteria, but the characteristics of the system, the receivers, and the… Read more
Jul 18, 2018 | By Edvard Csanyi
