Answer / meenakshi

The rotor of alternator consists of a coil of wire wrapped
around an iron core. Current through the wire coil -
called "field" current - produces a magnetic field around
the core. The strength of the field current determines the
strength of the magnetic field. The field current is D/C,
or direct current so that the current flows in one
direction only, and is supplied to the wire coil

Answer / rps

because we need constant magnetic flux so that windings of armature can cut them & induce emf.

Answer / k.prakashchandra

Field requires poles of alternative(N &S) fixed
polarities,which is possible only with DC

How to design inductive load for 3 phase 440v and maximum 5 amps for star or delta? Can we use a 15kW, 1450rpm motor for 15kW, 960rpm apllication?If yes.how......n.if thesame motor used what`s it`s sideeefect.

0 Answers  

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Can we check ELCB constantly from R1 to R8 phase in 1 no DB?

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please let me know , we have installed two separate motor for fire fighting system 1) 60 hp and 2) 15 hp the load is 74 AMPS and 20 AMPS then tell me the main power cable in Aluminum will be what thickness , the length is 225 mt from the main utility to fire pump house

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my question is Megger of cable insulation or swgr board meggerring some values in one day 50mohms,some other day checking different values(20Mohms). this tell that some person tell that that values ok. how to identify the megger value is correct. pls tell me the answer.

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if i have to use 14 kw what size of power cable can i use and size of earth cable also.

2 Answers  

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In dc motor starter there is less voltage required for holding contactor that's may why it is called no volt coil. but in ac starter why holding contactor is called no volt coil.

2 Answers   JSW,

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Is a contactor (or master relay) required between incoming lines and a VFD? The question goes to safety. If a contactor were used before the VFD and an e-stop engaged then the motor will coast to a stop (i.e. VFD loses power) instead of stopping much faster if the VFD braking fucntion were used. It would make more sense to keep power on the VFD.

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what is the difference between 50 hz freq. and 60 hz freq.? which is better and economic in them ?

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wat is mean by HRC fuse... WHY we choose it...?

3 Answers  

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in 132 kv transformer , in which range of transformer oil bdv required ? if it has around 50-55 , then how it was insulated the winding ?

3 Answers   Voltamp,

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what meaning of gd squre

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A ceiling fan moves Counter clockwise & a pedestal fan clockwise.....y the difference????

5 Answers   Alstom, NTPC,

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