Answer / manjunatha

the voltage generated due to the raotation of armature is
called back emf and it tries to oppose the terminal voltage.

Answer / alvin

back emf refers to the opposing voltage
induced in a motor when motor is
connected to a supply this is as per faradays
law , whenever a current carrying
conductor cuts magnetic field an emf is
induced in it, and is in opposite direction as
that of applied field...

Answer / jayan

Back emf is regeneration in dc motors

Answer / harekrushna sahoo

`back emf is happen in case of d c motor.it working to
oppose the terminal voltage.

Answer / kapil bahadure

Back emf :-DC motor connected to supply then magnetc flux
produced by armature windings.this magnetic flux oppose to
the supply voltage.its denoted by eb.7 also colled as
counter emf.eb occur in the dc machine.
eb=-V-IaRa.

Answer / srinu

back emf is produced in all motors due to rotation ,motor act as generator and produce emf ,this emf is oppose the applied voltage,this is called back emf,this is directelly propostionl to rpm

1)What will happen when 240 VDC supply is connected to 240VAC supply(DC supply +ve is connected to phase of AC supply & DC supply is to neutral of AC supply). 2)Also what will happen when 240 VDC supply is connected to 240 VAC supply in reverse polarity as of Sr. No 1.

2 Answers  

Is it necessary to place tap changer in secondary winding or we can use on both sides?

3 Answers  

what is the relation between reactive power and power factor for the what is the limit of reactive power and power factor

0 Answers  

what is the use of providing earthing for tanks? i know for lightning we use earthing ? Here one of my ONGC project there is no need of lightning protection and there is no power connection near by tank in that situation also ONGC asking earthing for tanks but we didn't understanding why they asking earthing? is anybody tell exact answer?

4 Answers  

What is d diff. btw Online & Offline UPS???

4 Answers   Emerson,

Why we are testing a tan delta test in transformer? which purpose conduting that test? and time priode test?

1 Answers  

Why 268hp induction motor taking different current in three different phases? (In which two phase having same current and one having higher value compare to other 2 phases.)

1 Answers  

What is EMC filter in VVVF Drive ?

0 Answers   Bengal Energy,

Consider three heater bank connected in 3 phase star with neutral.Each heater bank connected in each phase.So each phase get 230 volts supply.my question is,during balance condition, current flow in neutral or Not

0 Answers  

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.

0 Answers  

In a 3 phase system a neutral exists so that any unbalanced currents can flow through it towards earth.... but a phase demands a particular current as per the load attached to it....then where does the extra current come from the goes in the neutral??....I mean in an unbalanced system a phase demands a current as per its load attached....then where does the unbalanced current come from??

1 Answers  

what is the difference between online & offline caliberation of KWH meters. Can Digital meters be caliberated

0 Answers