Answer / ashraf nasr

mcb ' miniture circuit breaker' installed at the final
distribution circuits - as close as can be to loads - in
order to protect loads

mccb ' molded case cicruit breaker' used as a main breaker
for branches . it has higher rupture capacity

acb 'air circuit breaker' used as a main breaker for the
whole network - on the head of the transformer- since it
provide releabilty for its slow opertaion

vcb ' vaccum circuit breaker' it only differs due to the
damping meduie and its used in distributors

If in a 3 phase supply if the load current is 200A what value of current the each phase R,Y & B will carry?

5 Answers  

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why do you give the dc supply to field of alternator

3 Answers  

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I have 500A load (WHICH IS SEPARATE MDP PANEL),an MCC panel with 4000A Breaker.Already I have 2500A load.Can I connect this load directly to the Busbar since I have PROTECTION IN MY MDP Panel ?

4 Answers  

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What is the "IS" for Rising Main?

1 Answers   APTransco, NTPC,

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can any one explain me the where is the use of plc and scada

4 Answers  

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Why a transformer is rated in kVA and not in kW??

9 Answers  

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suri transmission

1 Answers   Bhel,

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Wheather there exist any dc transformer

6 Answers  

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1. What is differential relay? How it operates? 2.How to calculate the Short Circuit Impedance in Transformer? 3.What is the alternate solution for testing of polarity by using polarity tester while its milli ammeter does not works? 4. While testing the 33KV Busbar by using Hipot kit, what should be the test voltage we have to apply? 5. What is the procedure/activities to be taken to inject the current more than 2000A by using 2000A Loading Transformer? 6. Explain how you can give the overload setting to any Motor Protection Relay for a HT motors with formula and example? 7. Why restricted earth fault protection is needed? Why can’t differential Protection is sufficient? 8. What should be the minimum and maximum ohmic value for earthing? 9. Why DC Currents are not used in transformer? 10. What is the Frequency while we step up the voltage from 220V to 11KV? Is it possible? Explain it?

1 Answers  

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working principle of AC Servo Motor with its construction

1 Answers   TATA,

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This is reqd for a 1MW Solar power plant..We have 2DC outputs from the solar panels Connected to 2INVERTOR panels.. Output from invertor is 3ph,280v,500kva,50hz.These are connected to individual ACB.This has to be stepped up to 11KV ,1250KVA SYSTEM.Now can I use (1) one more ACBTO GIVE A COMBINED OUTPUT OF 1000KVA,280V & STEP UP THE OUTPUT BY USING a single two winding 3 ph transformer 11kv/1250kva. or (2)use the two outputs and connect to one three winding transformer of above rating..Pls suggestwith details.

1 Answers  

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what will happen reduce the transformer voltage from 415v to 406v, is it save the energy,? are this methodis good to reduce the energy.?

1 Answers  

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