Distance relay is widely used for the protection of high-voltage AC transmission line and distribution lines.
Which protection scheme is used for distribution lines?
3.2 Overcurrent protection scheme. The overcurrent protection scheme is used to protect the distribution lines of electric grids integrated with DER. This protection scheme is further classified into two categories, the phase overcurrent protection and the ground overcurrent protection.
Which type of backup protection is widely used for the protection of transmission line?
Types of Backup Protection:
Relays backup protection: Single circuit breaker is used to for both primary and backup relays. Breaker Backup protection: Separate circuit breakers is used for both protections in the same station.
Why do we need to protect the distribution lines?
Protection on the transmission and distribution system serves two functions: protection of plant and protection of the public (including employees). At a basic level, protection disconnects equipment which experiences an overload or a short to earth.
How are transmission lines protected?
Line Protection by Definite Time Relay
The relay nearest to the end of the line has minimum time setting while time setting of other relays successively increased, towards the source.
What is distribution protection?
Protection schemes are provided for distribution systems for quick disconnection of faulty section from the remaining healthy portion of power system. Main aim of protection schemes is to restrict the fault spread. Normally distribution lines and feeders are protected by over current relays .
What is distribution system protection?
The protection system in distribution systems consists of coordination of relay–relay on incoming feeding and fuse–fuse on laterals. Since 80% of all faults in distribution systems are temporary, reclosers are necessary.
Which type of backup protection is widely used in power system?
Relay Back-up : in this method , Different breakers are provided for main and back-up protection, both the breakers being in the same station. Breaker Back-up : In this method, separate breakers are provided for primary and backup protection.
What is the main and backup protection?
The main protection is provided in each section of an electrical installation. Backup Protection: The backup protection provides the back up to the main protection whenever it fails in operation or its cut out for repairs. The backup protection is essential for the proper working of the electrical system.
What are the types of backup protection?
Types of Secondary or backup protection
- Relay Backup Protection.
- Breaker Backup Protection.
- Remote Backup Protection.
- Centrally Co-ordinate Backup Protection.
What are the requirement of protection of lines?
The high level factors influencing line protection include:
- The criticality of the line (in terms of load transfer and system stability),
- Fault clearing time requirements for system stability,
- Line length,
- The system feeding the line,
Why is system protection required?
The main objective of using power system protection is to detach the faulty section from the system to make the rest of the portion work without any disturbance. In addition to this, it is used for the protection of power system and prevent the flow of fault current.
What are transmission lines used for?
The lines that carry radio waves from the radio transmitter to the antenna are known as transmission lines; their purpose is to convey radio-frequency energy with minimum heating and radiation loss. Heating losses are reduced by conductors of adequate size.
Which protection scheme is used for the protection of high and EHV transmission line?
Distance protection is a widely used protective scheme for the protection of high and extra high voltage (EHV) transmission and sub-transmission lines. This scheme employs a number of distance relays which measure the impedance or some components of the line impedance at the relay location.
How does line differential protection work?
Line differential relays basically operate on a difference in current into the line, compared to the current out of the line. For an internal fault, the current will flow into the line from both line terminals, with the polarity of the current transformers as shown in Figure.