Why Diffrential and Ref relays are used together although
Diffrential relay can protect Pri and Sec of Transformer

Answer Posted / bandarawy

The normal bias setting in a differential relay is 20%.
So, complete earth fault protection is not possible with
differential relay. That is why you need a seperate earth
fault relay with sensitive settings like 5%.

Is This Answer Correct ?    1 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

sir i had plane to do some project with the base of hopkinson test in AC supply its possible

1355


How to Decide the Location of Earth pit for Compressor in Oil Depo? and How to measure the resistance of earth pit Pls explain me with the help of Circuit Diagram?

1909


What is transister define the transister ammiter ,base, colector.

1720


Power factor =1.000 at factory in supply. However, PF = 0.8 at motor end. Current = 100 Amp, Voltage = 400 V. What is the power distribution loss? Can I reduce it by adding capacitor at the load feeder?

1592


What is a commutator?

598






what are the specifications we must look at to select a relay for any capacity motor?

1560


What are the material used for inductance coil?

689


WHAT ARE THE CHARACTERISTICS OF AN VOLTAG AMPLIFIER

1597


Define ampere

707


What is the effect on power factor, shown by a trivector meter; incase of reverse phase sequence. If the power factor of a system is lag what meter will show in case of reverse phase sequence connected to the meter. and What in case of lead.

1802


hi everybody how to design string combiner box (scb) internal parameters like bus bar and spd (surge protection device and fuse which place to set that,and also bus bar one particular cross sectional how much heat generated and how much power loss tell me Clearly and briefly

1532


why the difference arise between HT reading & LT reading (submeters fixed in complexes, apartments etc)if the power factos exceed from 0.9 to 1 can the ht meter reads fast?

2184


what will happen if the prime mover on the field excitation of the on-coming generator fails?Explain.

5002


difference between servo motor and synchronous motor

1872


in HT service 3ph 4 wire service Y-phase voltage shows zero . whether it is meter fault? or what be the reason ? if y-ph voltage zero ,can current is recorded? reasons for failure?

1405