Answer / nilkanth tailor

COZ, TORQUE IS DIRECTLY PROPORTIONAL TO THE SQUARE OF THE
CURRENT...SO THAT THIER IS VER HIGH CURRENT PRODUCE IN THE
STARTING OF DC SERIES MOTOR...AND IT IS DIFFICULT TO
CONTROL HIGH CUURENT...SO GENERALLY D.C. SERIES MOTOR
GENERALLY USEB IN TRAIN...CAUSE TRAIN REQUIRE HIGH STARTING
TORQUE...DUE TO HEAVY LOAD

Answer / naveen

Torque is proportional to flux and current.

reason why starting torque is high in series motor only is:
in DC series motor, flux is also proportional to current since the field winding is series with DC motor.

and the reason why its high in start is :
in starting back emf is 0 . current=(V-Ef)/R when Ef is 0 current attains high value which decreases as the speed of motor increases and thus the Ef.

Answer / ubendran mv

In SERIES MOTORS, the field windings are connected in
series with the armature coil. The field strength varies
with changes in armature current. When its speed is reduced
by a load, the series motor develops greater torque. Its
starting torque is greater than other types of dc motors.
Its speed varies widely between full-load and no-load.
Unloaded operation of large machines is dangerous.

The electrical energy required to raise the tempreture of a given amount water is 200 kwh. If the heat losses are 20%, the energy required is?

0 Answers  

---

What is reverse power relay?

0 Answers  

---

what is the meaning of TRF

1 Answers   Khidmah,

---

What will happen if twice the rated voltage is applied to a DC motor?

4 Answers   Toyota,

---

Do you know the faults occurs generally in motors and how to rectify them?

4 Answers  

---

Why heat produce in AC machine higher than DC machine?

2 Answers  

---

HARMONICS ARE ALWAYS IN INTEGER LIKE 2ND OR 3RD HARMONICS,NOT IN FRACTION LIKE 0.5 HARMONICS.....????????

2 Answers  

---

we want low electricity at lower speed of fan.what we have to do?

5 Answers  

---

why we can stote dc? why we cant store ac?

0 Answers  

---

What is K-rated transformer? What is the use of it? What can be the size(pls provide calculation if possible) of K- factor transformer for 550kW,690V motor operating with drive (VFD)?

0 Answers  

---

Dear friends I want to design busbar for1600 kva transformer(i.e2100 amps) what are all the factors to be considered before selectinga busbar what are all the standard sizes of busbars what is the formula for finding current of copper and aluminium busbar

0 Answers  

---

i want all question & answers of the written exam

1 Answers   Essar, L&T, MES, RRB,

---