Answer / mn krishnamurthy

usage of lot of frequency drives and votage regulatiors with IGBT and SCR for heavy loads with start and stop and linear varying voltage for speed control created Harmonic currents

Application of DC motors is generally restricted to a few load speed applications because of _____.

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In case of 3 phase motor why it is called single phasing by failure of one phare unless there is rest two phase are acting. ?

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magnetizer priciple

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WHAT MEANT BY SEVICE FACTOR?

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We have drive feeding an output contactor for a 5000 hp motor @ 5kV application. The motor FLA is 629amps x 1.25% service factor = 786.25 amps The cable that we current have in place between the drive and the output contactor is 350kcmil- MV-105 (parallel cables). Per the NEC table 310.60 (C) (69). This show the cable ampacity is at 615 amps per cable for a rating of 1230 amps. We have derated the cable for the cable tray and the multiple cables application and our calculations show that after the correction factor factor we are at 922amps. 1230 amps x .75% correction factor factor = 922.5 amps. The customer is driving us to then use another safety factor of .25% off of the already derated cable. Can you please provide a longhand calculation for your solution on this application?

0 Answers   Siemens,

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1) Why distributiion system decided 11 kv, 33 kv, 66 kv, 132 kv, 220 kv, 400 kv, 2) In 3 Phase line terminal of capacitor, why used for power factor improvement. 3) Why used rating KVA in transformer?

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how we can calculate LT side current of transformer

2 Answers   L&T,

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What is the function of capacitor in electrical circuits?

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why wire sizes are 3/29 or 7/29 and why not wire sizes are 2/29 or 6/29?

0 Answers   OGDCL,

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what is the voltages using in movie theaters??? why ??why not other??

0 Answers   Lanco,

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block diagram of 2 ups system connected in hot stand by mode?

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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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