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A definite time overcurrent relay operates like an instantaneous overcurrent relay coupled with a timer. once current reaches the pickup value, the relay overcurrent relay will trip, which initiates the timing circuit. as long as current stays above this pickup value, the timer will continue to time. Once the definite time setting is reached, the timer will close the relay tripping contacts.
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Can you define the term OCR in electrical terminology?
OverCurrent Recloser, or OverCurrent Relay.
What do relay and circuit breakers use?
No. A relay is an electric switch and a circuit breaker is an overcurrent device.
What is pick up of a relay?
The "pick up" of a relay is a setting at which the relay will begin to operate. Such as an overcurrent relay - if the pickup is set to 5A, when 5A is flowing through the relay, the relay will operate.
Why use over current relay?
To protect things from getting damaged by overcurrent.
What is difference between reverse power relay and directional relay in electrical protection?
A reverse power relay is a directional overcurrent relay. Directional relays are relays that sense power flow in one direction, and include (directional) overcurrent relays, reverse power, and impedance based relays. So a reverse power relay is a directional relay, but a directional relay is not necessarily a reverse power relay.
Earth fault relay and an overcurrent relay Methods to energise an earth fault relay?
Earth fault relay and an over current relay Methods to energies an earth fault relay with simulation diagram?
What is relay coordination system?
Coordination between upstream relays for a overcurrent fualt on down stream.
What is meant by residual overcurren?
Residual overcurrent protection is often provided in modern microprocessor based relays that have three phase inputs, and no neutral input. Sometimes this is provided even if a neutral input is present. It is similar to neutral overcurrent, where the neutral current is directly measured through the neutral input of the relay. for residual overcurrent, the three phase currents are vectorially summed together to form the residual overcurrent. This relay measured 3I0 current, or ground current.
What is the difference between voltage restrained overcurrent protection and voltage controlled overcurrent protection?
The voltage-restrained overcurrent relay adjusts the pickup setting and characteristic curve of the overcurrent function based on the system voltage. The relay is set pickup greater than overload, and sensitivity increases as the voltage drops. The voltage-controlled overcurrent relay uses an undervoltage element to supervise the operation of the overcurrent element. When the voltage drops below a predetermined level, the undervoltage element permits the operation of the time overcurrent units. Voltage-restrained overcurrent relays can provide faster backup protection than voltagecontrolled overcurrent relays, particularly in cases where the generator voltage does not drop significantly below rated voltage during fault conditions. If the generator voltage always drops below a given voltage level for all faults in which operation is required, the voltage-controlled overcurrent unit may be set to provide faster overall clearing speed
What is idmt relay?
Inverse Definite Minimum Time Lag = IDMT relay It's a electromagnetic type rotating disk relay. Tripping time of relay decreases with increasing fault current. see http://myweb.tiscali.co.uk/robert.booth/uni/docs/Power%20Supply%20Assignment%203.pdf
Why would your lights and horn not shut off?
Have you checked for a relay that might have been damaged when the fuse blew? With an overcurrent, it is possible for the relay to pick up and then become 'welded' so it will not release. If you find the relay and remove the cover, the contacter should move when you apply a little pressure to it. If this doesn't happen, replace the relay. Much harder to check would be if insulation melted during the overcurrent and fused power to a horn and light wire. Relay for sure.
What is meant by IDMTL type relay?
Inverse definite minimum time lag relay
