Answer / amit rajak

contactor- it is simply a switch or combination of switch
which is used to open or closed the circuit having
different phase wire in single phase circuit or three phase
circuit by automatic that is by pneumatic ( by air ) or
also manually.


relay -it is a protecting device that is used to protect
the circuit from faults.
it is basically a sensor which senses the fault in
electrical circuit having different parameters .it ihas a
predetermined set parameter which makes comparision under
fault condition and provides the initial signal to the
circuit breaker which fif finds the parameter more than
the predetermined magnitude or value it trips the circuit
examples of relays are:
1).electromagnetic relays
2).thermal relays
3).induction relays
4).differential relays
5).distace relays

few modification are used in these relays to suite certain
operation.

Answer / guest

relay is act as a electromagnetic switch conductor is copper
strip

What is earth system using on the floater TN-S or TT. Iam not sure and what ICCP

0 Answers  

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Give idea about General Engineering. From which book i can study this topic. Pl. reply me via email. My email is ravi@bhelhwr.co.in, also give the name of book/website, from where i can prepare it.

0 Answers   TATA,

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description about dry type transformers

0 Answers  

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what happen when we add mentos in cold drink?& why?

0 Answers  

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what will happen if phases are not shorted with neutral in transformer impedance test? and if neutral is not connected with ground?

1 Answers  

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how much kn lightning arrestor is used in 11kv line

8 Answers   Power Grid,

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What happen if the 24 volt DC supply is disconnected from air circuit breake ?

2 Answers  

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What is the technical reason for adopting color coding of three phase system as RYB.

11 Answers   ABB, ERDA,

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why we use iron corn in transformer instead of wooden core

12 Answers  

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sir , what happen if we decrease ( approx 3 inch ) the lenth of shaft in 110KW Induction , three phase motor. actually a 110KW motor is couppled with star couplling to 120TR compressor. When we doing maintenance in compressor it is required to skid the motor backword and resulting dis- alightnment . so we want to change the tyre coupling in place of existing coupling. so it is required to cut off the rotor aprox 3 inch form driving side.

2 Answers  

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Why air circuit breaker off due to power failure?

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An 11kv system consisting of an underground cable to a sub station about 300 meters away was shut down for about 10 hrs. On energising, it tripped off on earth fault about 10---20 mins later 6 times but since than it is not tripping.its already 3 weeks now. The SPAJ was found to be fine. what could be the cause.No test had been done to determine the cause of the trippings till now because of demand.

2 Answers  

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