when we decide to use soft starter drive or vfd drive in mcc to operate apump?

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What is principal to reduce earth leakage current with isolation transformer? When isolation transformer is installed in input stage of system, earth leakage current is reduced. the reason is why the leakage current of 2nd stage of isolation transformer does not affect the 1st stage's leakage current. I would like to know the reason. As you know, earth leakage current is a kind of AC. So, How to reduce earth leakage current in case that isolation transformer is used?

2 Answers  

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Why Utility Distribution System in India is mainly at 11 kV? Why not Utility go for 33 kV?

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How can calculate thermal overload in relay?

1 Answers   ABB,

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what is transformar load balancing ?

2 Answers   L&T,

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Differnce between Analog & Digital

1 Answers  

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what is different between IP55,IP54 and IP66?

2 Answers   ABB, Global Industries,

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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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What is mean by power factor?

18 Answers   Shreem Electric Ltd,

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a power supply to be constructed from voltage cells is required to provide Max. 20A Current with a terminal voltage of 6v.Several voltage cells are available each of which has terminal voltage of 1.5V & each of which can supply a max current of 5A .the no of cells required will be ??

5 Answers  

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earth also having a gravitational force (magnetic field of north and south)but it attracts any object compare to this theartifical magnetic cant perform same as earth why?

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Why efficiency in thermal power plant is low?

0 Answers  

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