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It is the one type of coil in the electrical motor starters. It is used to release the switch, i.e. turns off the motor, when heavy load is connected to the motor. It is used for the protection purpose.
Wiki User
∙ 13y ago
Wiki User
∙ 12y agoit is a relay that save your electrical device from flowing over current.as over current flow it brake the ckt. by tripped itself.
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What the three types of over current protection relay and describe the principles of operation?
over current protection relay
Is a current relay same as potential relay?
current relay are using for over current low state & high state.but potential relay are related to voltage.
What is ocr efr uvr referred to in air blast circuit breaker?
ocr-over current relay(senses the over current in the circuits) efr-earth fault relay uvr-under voltage relay
How does time inverse over current relay work?
Over Current (Inverse Time) Over current relay function monitors the general balanced overloading and has current/time settings. This is determined by the overall protective discrimination scheme. There advantage over definite time relays is that they can have much shorter tripping times can be obtained without any risk to the protection selection process. These are classified in accordance with there characteristic curves, this indicates the speed of the operation. Based on this they are defined as being inverse, very inverse or extremely inverse. The typical settings for these relays are 0.7-2In (normal or rated generator current) in 1-10 second. Inducing a calibrated test current through the normal load current tests this relay.
What is defrential protection relay?
I am going to assume that you are asking about a differential relay. It is basically just that- it compare two different sources and will trip at a set value value of the difference. These can be directional as well. A couple of examples are transformer protective relays and bus differential. A transformer relay will measure the amount of current coming into the transformer and the amount of current going out. If there is a disparity due to an internal fault the relay will trip the supply source and deenergize the transformer. Same for the Bus differential.
What is the difference between an earth fault relay and an over current relay?
earth fault relay is also a type of over current relay but the set value of current or relay sensing current is much less than the maximum load current.in over current relay relay sensing current ise than maximum load current mor
What is DTOC relay?
A definite time over-current relay operates like an instantaneous over-current relay coupled with a timer. Once current reaches the pick-up value, it initiates the timing circuit. As long as current stays above this pick-up value, the timer will continue to time. Once the definite time setting is reached, the relay gives trip signal to the circuit breaker.
What the three types of over current protection relay and describe the principles of operation?
over current protection relay
Is a current relay same as potential relay?
current relay are using for over current low state & high state.but potential relay are related to voltage.
How do you test over current relay?
Normally the Over current relay is connected using a suitable CT (Current Transformer). Say the CT ratio is 100/5 Amps. (secondary is normally 5 or 1 amps). 100 Amps in the primary induces 5 amps in secondary which flows through over current relay circuit. Secondary current is proportional to the primary current. To test the OCR , inject the current into relay circuit ranging from 0 to 5 amps in steps (which represents upto full load current on primary). Relay will operate accordingly operate the trip contacts. These relays are normally with a time factor setting as well.
How does an over current relay work?
An over current relay will operate when current exceeds its design rating. This application is intended protect loads or circuits from excessive current.
Over current relay?
in electrical circuit current will increase specific level (full load current).its call over current
What are time delay relay characteristics?
Time delay protective relays used in the power industry can be time over current or voltage, or definite time over / under voltage / over current.Definite time type relays use an over / under voltage / current element that picks up when voltage / current reach a specified level. When this picks up, a timer is started. If current / voltage stays above / below the pickup value for long enough to allow the timer to expire, the relay trip contacts are closed.Time over current elements use an inverse time - current curve to define speed of operation, so the more current is present, the faster the relay will operate.
What is ocr efr uvr referred to in air blast circuit breaker?
ocr-over current relay(senses the over current in the circuits) efr-earth fault relay uvr-under voltage relay
What is instantaneous over current relay?
Instantaneous over current relay, which operates very fast with no intentional time delay and the operating time of these relay can be as low as 0.01sec . These relay operates only when the impedance between the relay and the source zsis very small compared to the impedance to the impedance of the protected section zl .
Function of earth fault relay?
An "earth fault relay" is a bit ambiguous. A relay used in the power system to detect neutral or ground faults measure the vector difference of the three phase power, or measure the neutral current directly. If current is above a set trip point, the relay will operate. If you are referring to GFCI's, they effectively measure the current flowing in and the current flowing out on the two "hot" wires, and if these do not cancel each other out, then the GFCI will trip. This is because if current in does not equal current out, then some current must be flowing out a different way (to ground!).
How does time inverse over current relay work?
Over Current (Inverse Time) Over current relay function monitors the general balanced overloading and has current/time settings. This is determined by the overall protective discrimination scheme. There advantage over definite time relays is that they can have much shorter tripping times can be obtained without any risk to the protection selection process. These are classified in accordance with there characteristic curves, this indicates the speed of the operation. Based on this they are defined as being inverse, very inverse or extremely inverse. The typical settings for these relays are 0.7-2In (normal or rated generator current) in 1-10 second. Inducing a calibrated test current through the normal load current tests this relay.
