Answer / tpfasil200

Direction of rotation of synchronous motor is determined b y its starting direction,as initiated by inducyion motor action. Thus, to reverse the direction of a 3 phase synchronous motor, it is necessary to first stop the motor and then reverse the phase sequence of the 3 phase connections at the stator. REVERSING THE CURRENT TO FIELD WINDINGS WILL NOT AFFECT THE DIRECTION OF ROTATION

Answer / tpfasil200

Direction of rotation of dc motor can be reversed in 2 ways
1.reversing current through armature and interpole windings(if they exist)
2.reversing current through field windings,ie,through shunt and/or series winding..but not through interpole windings(if they exist)
Reversing current through the armature is preferred because reversing current through the field windings involves breaking and making highly inductive currents of the field windings.Also field reversal of compound motors requires connections of both shunt and series windings to be changed..

Answer / prasanth

1.in alternator the induced emf is reduced due to retentive property of the field magnet when reversed.

In IDMT RELAY the term minimum (M) indicates what?

7 Answers  

---

what are the types used for alternator earthing,what will happen if more than two alternator is working in parallel with each having own system earthing.is there any possibility for circulating current in between two system.

3 Answers   BEL,

---

How many electrones need to flow in one second to equivalent to one Ampere.

3 Answers  

---

Different STANDARDS (BS, IS, IEC etc) gives different informations on CT specification. How they correspons w r t each other (i.e I mean to say BS provides "knee point voltage" but IS does not, then how can i select CT)

0 Answers  

---

what is the different between HT auxillary relay resistance and transformer tripping relay resistance?

0 Answers  

---

---

Can an inverter be used as a converter? How?

0 Answers  

---

Sir,In our company there are 3 caterpillar make(capacity:(1) 3.3KV,2.5MW(2)3.3KV,2.5MW & (3)3.3KV,1.9MW) & 1 deutz make (capacity:11KV,3.8MW)gas engines utilised,all are running in paralell. There are three transformer utilised,(1) 6.25MVA,3.3KV/22KV,Impedence voltage:6.7% used for two generator,both are 2.5MW(2)5.5MVA,3.3KV/22KV,Impedence voltage:7.2% used for one generator of 2.5MW & (3) 5.5MVA,11KV/22KV,Impedence voltage:7.8% used for one generator of 2.5MW.all generator breakers capacity of 1250Amps. Sir,I want the details of fault level calculation of generator,transformer individually & for whole system. If you require any information from me.feel free for contact me sir.pl.send the answer of my question as the earliest as possible.

0 Answers   Piramal Healthcare,

---

what is the safe meggar values for motor, transformer HT, LT and Cables? IF we want to replace I/C bay at our 220 kv substation which is of 140 mw load capacity bay to be replaced by 400 mw capacity bay.other than CT(1200/1) what are the other equipment i have to replace. why we generally use 3.5 core cable or in other word 1/2 core for neutral and also confirm me that in balance conditiob(3 phase)current in neutral will zero

0 Answers   Jindal,

---

what will happen if 11KV is given to 1.5 square mm cable connected with constant load of 10A ?what will be the condition of cable after injecting the voltage?

1 Answers  

---

Why size of HT cable is less then LT cable inspite of the fact that voltage is higher in HT cable?

2 Answers   L&T,

---

what is prniciple of three phase IM?

3 Answers  

---

What is the full form of SON-T lamp?

1 Answers   HAL,

---