Answer / vinodh kumar ks

A shunt motor speed is controlled by the field. Think of it
like this: The actual resistance of the armature is very
small so by Ohm's law the armature current (locked rotor)
will be very large. But as the motor turns it acts like a
generator and that generated voltage reduces the current
that the motor draws. Soon at no load the motor is turning
fast enough that very little current is required. if you
make the field stronger by increasing the field current the
generator action (called back EMF) is increased and the
motor doesn't have to turn as fast to balance the voltage
applied to the armature.
So the rule is reduce the field to increase the speed.

Answer / somasundaram t

ward leonard method is one of the dc motor speeed
control.this method requires combination of one motor
generator set for controlling the one DC motor.so this
method becomes expensive.and also requires high
maintanence.power consumption ,losses also more.this method
got too failure after the power semiconductor controllers
has been introduced.

whats relation b/w motor current & friqency

1 Answers  

---

why different series of vfds (like allenbradley)are used in industry ?

0 Answers  

---

11KV electrical line going through the forest in cloudy night ,how can we find the direction of line.

5 Answers   Bhel, Cesco, HZL, Nesco,

---

What is the function of a neutral reactor.

0 Answers  

---

If the load of transformer is getting more than its rating,,,than how to overcome this problem? Suppose thee rating of transformer is 315kva and the load is going beyond than the rating say around load: 352kva... Than how can we solve this problem without deducting the load.

14 Answers   Hyundai,

---

---

Does induction motor start with dc power supply????

4 Answers   Essar,

---

What is the Diff. btw Fire Alarm System & VESDA System??????

1 Answers   Emerson,

---

how u select control transformer for a mccb panels or any panels?for expample we hav 440 volts maim supply and control volts is 230v?

0 Answers  

---

how rectifier transformer work in electroststic precipetatore(esp?

0 Answers  

---

what's float charger and boost charger? why it's used?

2 Answers   APCPDCL, PTCL, Rolls Royce, Siemens,

---

What is Residual Voltage & Residual Current?

4 Answers  

---

why would the rotor rotate at sub synchronous speed against the direction of rotating flux when d rotor of 3 phase IM is connected to 3 phase balanced supply and the stator windings are shortcircuited ??

0 Answers  

---