Why the brushes used in dc machines are made of carbon not from other metal?

3 Answers  

---

What happens if ac excitation is given to the field of an alternator

3 Answers   Aurobindo,

---

we have taken HV test of 2.5 k and Megger test on 11 kv HT cable.here it shows no fault but when we are charging the same cable with 11 kv supply why the VCB 11 kv gets tripped can anybody define the possible cause of fault ?

4 Answers   MAHINDRA,

---

Earth has zero potential then what would be the neutral potential ?

0 Answers   JLL,

---

how does a tube light choke working?

2 Answers  

---

---

What is diversity factor and how to calculate it

2 Answers   Al Faraa, Amul, Pentagon, Sobha Developers,

---

how to calculate knee point voltage for pt?

1 Answers   Amec,

---

the input mechanical power of a single alternator is increased,its RPM increased but in case of an alternator synchronised with grid its RPM does not increased with increase of input mechanical power. why?

3 Answers   Bhel,

---

how to change the load sharing between two synchronized identical alternators when both are running with Diesel engine? assume both are feeding to same feeder?

1 Answers   BARC,

---

1)How much current can a 3-1/2 core 100 mm wire carry? 2)What are the special cables required for explosion proof wiring? 3)In case you do not have coal and salt for earthing, how can you achieve good temporary earthing? 4)One horse power single phase motor is more likely to get hot than a one horse power 3 phase motor. Is it true or false, if true why? 5)What are the different types of soft starters for large motors?please explain?

0 Answers   TATA,

---

when is the Ohms law is applicable?

11 Answers   ABB,

---

WHAT IS MEANT BY vfd(VARIABLE FREQUENCY DRIVE )HOW CAN WE APPLY VFD TO MOTOR ? I WANT FULL DETAIL IF ANYBODY KNOW THE WEBSITE FOR THAT PLZ SEND .THANK U

2 Answers  

---