Protection Relays
The relay is a well known and widely used component. Applications range from classic panel built control systems to modern interfaces between control microprocessors and their power circuits or any application where reliable galvanic separation is required between different circuits. Altough considered to be a relatively simple component, the electromechanical relay and its technology is complex and often misunderstood.
History of relay
The earliest electrical relays were developed in the 1830s, as people began to recognize that such switches could be extremely useful. Historically, electrical relays were often made with electromagnets, which continue to be used today, although for some applications solid state relays are preferred. They key difference between electromagnetic and solid state options is that electromagnetic relays have moving parts, and solid state relays do not.
Electromagnets also conserve more energy than their solid state counterparts do.
Usage of relay
One of the reasons an electrical relay is such a popular tool for electricians and engineers is that it can control electrical output which is higher than the electrical input it receives. In the example discussed above, if the ignition connected directly to the battery, heavy duty insulated wiring would be needed to connect the steering column to the battery, and the ignition switch would also need to be much more robust.
A variety of circuits can be connected to an electrical relays. Relays can be used as amplifiers for electrical energy, as in the car example, and they can also connect to things like alarm switches, activating when a circuit is broken to trigger an alarm.
Many electrical failsafe systems utilize electrical relays which turn on or off in response to things like a current overload, irregular current, and other issues which may arise. These electrical relays trip to shut the system down until the problem can be addressed.
Browse guides and papers
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Today (11/19/2018) you published an article on protective relays polarity. I would like to download a copy. Thankyou.
Dear sir, i would have the guideline document related to scheme preparation of protective lines , transformer , generator etc.
I want to download this file
sir pls tell me how differential relay works ?
I have a crompton greaves drive in a equipment, i am unable to vary its speed from HMI. Also unable to find drive manual.
Can you help with probable solution
Thanks for information
Tahnk you very much for this website and for it’s team
Sir.
In India What % of T&D Losses are standardized.
Hello Jawaid,
Here is a short reply to your query..
Here in India 33kV, 22kV and 11kV level is considered as sub-transmission or HV distribution voltage level. Being a vast country distribution network and parameters differ widely from State to State and so does the T&D loss level. The loss level (which includes losses in HV lines and LT lines) in some pockets is around 10% and even less than that. However, it is as high as 30 to 40% in some rural and remote pockets.
We have two Thyro-A (AEG) in our substaion and both of them flashing on pulse inhibit.
we checked LED MESSAGES and have been detected that one of Frequency error or SYNC error can be occured, and SYNC error has more probability. If SYNC error be right fault, how can i remove it? Can you help me please?
Good work. thanks for the information
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I would like to know the reason for equi- potential wires getting disconnected at CT body end from main transformer incomer feeder. Feeder tripped on transformer differential & LV side restricted earth fault protection. Pls Explain…
yes it is possible, when ever equipotential ring is disconnected from ct there is a chance of occuring error on measuring of ct, actual current flow on ct and measured current on ct will differ in that situation u get the trip from both differential and ref protection.
please explain can we use measurement CT’s for protection relay ? if not so why ?
because of the ct winding always short suppose it is used for protection it will be open that time huge current flow through the ckt and it will damage the property or human body.
i had no idea about numerical relay, please tell full detail about that how to make setting,progarmming,configuration and progarmming logic. please sir,