The back-up protection acts like main protection. The backup protection can be classified as: – Relay back-up : Same circuit breaker is used by both main and back-up protection, but protective systems are different. Separate trip coils may be provided for the same-breaker.
What is primary and secondary backup protection?
If the primary protection operation falls into trouble, then secondary protection disconnects the faulty part from the system. Moreover, when we disconnect primary protection for testing or maintenance purpose, then secondary or back-up protection will act as primary protection.
Which relay is used for backup protection?
The relays used in back up protection are called back up relays. It is important to note that backup relays are independent of factors that might cause primary relays to fail to operate. In order to give the primary relay sufficient time to operate, a backup relay operates after a time delay.
What is primary and back up protection?
Primary protection (Main protection) is the essential protection provided for protecting an equivalent/machine or a part of the power system. As a precautionary measure, addition protection is generally provided and is called Backup Protection.
What are the types of back up protection?
Types of Backup Protection:
Breaker Backup protection: Separate circuit breakers is used for both protections in the same station. Remote backup protection: one breaker for primary protection in one station and then another breaker for backup protection in another station.
What is local breaker backup protection?
Local Breaker Back-up Protection or LBB protection is provided to ensure the healthiness Power System by isolating the faulty section in case of failure of tripping of Breaker intended for tripping on sensing fault. This protection is also called Breaker Failure Protection.
What is the primary protection?
Primary Protection:
The main protection or primary protection is the first line protection which provides quick-acting and selective clearing of a fault within the boundary of the circuit section or element it protects. The main protection is provided in each section of an electrical installation.
Which relay is not used in backup protection?
Standard overcurrent relays are not recommended for backup protection of a generator. The backup relay must be capable of detecting the minimum generator fault current.
Which type of back up protection is widely used for the protection of transmission lines?
Distance relay: Distance relay is widely used for the protection of high-voltage AC transmission line and distribution lines.
What is backup impedance protection?
The Backup Impedance Protection is used to protect the generator from supplying the over loaded or faulty system and it is a definite time graded protection, for a short circuit phase fault in Generator, Generator Transformer, Bus duct or as back up of uncleaned external network fault.
What is current differential protection?
Differential protection is a unit-type protection for a specified zone or piece of equipment. It is based on the fact that it is only in the case of faults internal to the zone that the differential current (difference between input and output currents) will be high.
What are the two types of protection?
It is a usual practice to divide the Types of Protection scheme into two classes viz. primary protection and back-up protection.
What are the four types of backup?
Each backup program has its own approach in executing the backup, but there are four common backup types implemented and generally used in most of these programs: full backup, differential backup, incremental backup and mirror backup.
What is bus bar protection?
What is Busbar Protection? Busbar protection is a protection scheme meant to protect the busbar from electrical fault. Various feeders are connected to a busbar through circuit breaker in any of the bus configuration viz. Double Busbar arrangement or one and half breaker scheme.
What is one and half breaker scheme?
In One and Half Breaker Scheme, three breakers are connected between the two buses. Each Breaker is provided with two Isolators and two Earth Switches. These Isolators are provided to physically isolate the Circuit Breaker for maintenance.
What is the purpose of back up 1 point protection *?
The backup fuse protection is mainly used where the main protection of the adjacent circuit is unable to back up the main protection of the given circuit. The backup fuse helps us to control the maximum current in an electric circuit. The fuse wire melts and thereby breaks the continuity of a given electric circuit.
Where is differential relay used?
Generally, differential relays are used to protect the equipment against internal faults. Merz price protection scheme is one form of the differential relay which is used to protect the stator winding of Alternator from the internal faults. Differential relay is also used for the protection of transformer winding.
What is overcurrent protection relay?
An overcurrent relay is a type of protective relay which operates when the load current exceeds a pickup value. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay. The ANSI device number is 50 for an IOC relay or a DTOC relay.
Which are the two types of relays?
Types of Relays – A Thomas Buying Guide
- Relays are electrically operated switches.
- Electromechanical relays have an electromagnetic coil and a mechanical movable contact.
- Solid-state relays are solid-state electronic components that do not have any moving components, which increases their long-term reliability.
Which of the following relay is provided as the primary protection of transmission lines Mcq?
Answer. 7. Which of the following relay is used for phase fault protection of short transmission lines ? (a) Reactance relay.
Why is Differential Protection called unit protection?
In other words, it is possible to design protection systems that respond only to fault conditions occurring within a clearly defined zone. This type of protection system is known as unit protection. Certain types of unit protection are known by specific names, e.g. Restricted Earth Fault and Differential Protection.
What is the most common secondary fall protection system used by most workers?
Guardrails. Guardrails should be your first choice when it comes to preventing falls. They provide workers with the best protection because, when erected properly, they actually eliminate the fall hazard. With guardrails in place, workers can’t fall because there is no open edge.
What is auxiliary relay?
What is Auxiliary Relay? Auxiliary Relays are designed to switch more load than the capacitance of the switching products. These components are used for the multiplication of contacts where more than one contact is required.
Why is backup protection needed?
5], backup protection is intended to operate when a power system fault is not cleared or an abnormal condition is not detected in the required time because of failure or inability of other protection to operate or failure of the appropriate circuit-breaker(s) to trip.
What type of back up protection is used for alternators?
What type of back up protection is used for alternators? IDMT relay.
What is the function of differential protection relay?
The main function of differential relay was to send trip signal to circuit breaker when there is a certain difference current value between primary side and secondary side of the transformer [1].
What is unrestrained differential protection?
The unrestrained differential element in transformer protection is clearly needed as a means of tripping a failed transformer when the restrained element is severely restrained or blocked during energization.
What is hot backup and cold backup?
A hot backup is used when a full backup is needed and the service level does not allow system downtime for a cold backup. Cold backup—Users cannot modify the database during a cold backup, so the database and the backup copy are always synchronized.
What are the 3 types of protective devices?
Natures of Protection Devices
- Fuse.
- Circuit Breaker.
- PolySwitch.
- RCCB.
- Metal Oxide Varistor.
- Inrush Current Limiter.
- Gas Discharge Tube.
- Lighting Arrester.
How many types of circuit breakers are there?
There are three basic circuit breaker varieties: standard breakers (which include both single-pole and double-pole circuit breakers), ground fault circuit interrupter circuit breakers (GFCIs) and arc fault circuit interrupter circuit breakers (AFCIs).
Which type of backup should you use to backup a set of files?
A full backup is the most complete type of backup where you clone all the selected data. This includes files, folders, SaaS applications, hard drives and more. The highlight of a full backup is the minimal time it requires to restore data.
What is full backup and incremental backup?
A full backup of a data file includes all used blocks of the data file. A full backup can be either an image copy or backup set. An incremental backup copies only those blocks in a data file that change between backups.
What is local backup protection?
Local Breaker Back-up Protection or LBB protection is provided to ensure the healthiness Power System by isolating the faulty section in case of failure of tripping of Breaker intended for tripping on sensing fault. This protection is also called Breaker Failure Protection.
What is auto reclose relay?
Automatic reclosing relay is designed to initiate multiple reclosures of a circuit breaker which has been tripped by protective relaying. It is essentially a timing device, with a heavy-duty stepping switch operating contacts in response to impulses from a solid-state electronic timing circuit.
What is reverse blocking protection?
The reverse busbar protection is a cost-effective solution for accelerated clearance of busbar faults in distribution systems. It can only be applied on single busbars with a fixed direction of power-flow and fault current flow. In picture 3, a typical application is shown.
What are the two types of protection given for busbar?
This type of busbar protection has two types: low-impedance biased differential protection and high-impedance differential protection, as described here.
What is double busbar?
In double bus bar system two identical bus bars are used in such a way that any outgoing or incoming feeder can be taken from any of the bus. Actually every feeder is connected to both of the buses in parallel through individual isolator as shown in the figure.
What is bus bar and types?
Such type of arrangement uses two type of busbar namely, main busbar and the auxiliary bus bar. The busbar arrangement uses bus coupler which connects the isolating switches and circuit breaker to the busbar. The bus coupler is also used for transferring the load from one bus to another in case of overloading.
What is difference b/w primary and back up protection?
Primary protection (Main protection) is the essential protection provided for protecting an equivalent/machine or a part of the power system. As a precautionary measure, addition protection is generally provided and is called Backup Protection.
What is the primary protection?
Primary Protection:
The main protection or primary protection is the first line protection which provides quick-acting and selective clearing of a fault within the boundary of the circuit section or element it protects. The main protection is provided in each section of an electrical installation.
What is bus bar protection?
What is Busbar Protection? Busbar protection is a protection scheme meant to protect the busbar from electrical fault. Various feeders are connected to a busbar through circuit breaker in any of the bus configuration viz. Double Busbar arrangement or one and half breaker scheme.
Which relay is used for protection of transformer Mcq?
Buchholz relay is used for the protection of transformers from the faults occurring inside the transformer.
Which type relay is used in over current protection?
Inverse Time Overcurrent Relays (IDMT Relay) In this type of relays, operating time is inversely changed with current. So, high current will operate overcurrent relay faster than lower ones.
What are the 5 different types of relay?
What are the Types of Electrical Relays
- Electromagnetic relay. Electromagnetic relay is the simplest, oldest and most widely used relay.
- Latching relay.
- Thermal relay.
- Reed relay.
- High voltage relay.
- Time Relay.
- Current and voltage relay.
- Differential relay.
Which of the following relay Cannot used in backup protection?
Standard Overcurrent Relays
Standard overcurrent relays are not recommended for backup protection of a generator. The backup relay must be capable of detecting the minimum generator fault current.
Which of the following relay is used for short transmission line Mcq?
Reactance relay is used for the phase faults in a short transmission line.