What is inverse definite minimum time lag relay? Where is it use?

0 Answers   TATA,

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What is different between DOL(Direct on line starter), VSD, S/S(Soft starter), and A/T(Auto Transformer)

2 Answers  

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Why in power plant projects we see DOL starting method used for motors upto 160 kW instead of star delta method

0 Answers   UCC,

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which oil used in transformer?

5 Answers  

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WHY WE CAN GENERATE POWER IN 3PHASE MODE ONLY NOT IN 4 OR 5 PHASE?

10 Answers  

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Is there any specialised book to refer about fault level calculation both in MV and LV side??

0 Answers  

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Can the efficiency of transformer be measured with the help of wattmeter readings taken at primary and secondary side? Support the answer.

2 Answers  

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What is the Nyquist criterion regarding control systems?

0 Answers   GE,

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why voltage between neutral and earth, with out secondary grounded distribution transformer

1 Answers   Wescosa,

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What is the difference between IGBT and TRIAC?

3 Answers  

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Q-1 what are the structural and operational difference between a distribution and a power transformer? Q-2 what is skew in motors? Q-3 draw equivalent circuit of transformer Q-4 explain with phasors how pf is improved with loading in induction motors Q-5 DIFFERENT METHODS OF CABLE LAYING(interviewer asked if i heard new chemical based earthing system next) Q-6 pi model of medium length trans line Q-7 v/f control?why Q-8 vacuum circuit breaker operates in?

1 Answers   Vijai Electricals,

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One of our gas turbine generator unit "1st stage rotor ground fault" alarm was occured several times. we tried to measure some voltage vulue ground fault protection relay (UNS3020a made by ABB and we measured the value of: Ground: 0.9VDC 5V: 5.8VDC 24V: 23VDC u+: 300 – 350mVAC Rf1: 17.5mVAC Rf2: 17.6mVAC The unit still running and the alarm was reset. As of 6pm yesterday and unitl now no alarm happened again. I our protection relay was defective?

1 Answers  

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