Answer / baikunth

generally there are two types of speed control systems are
available in induction motor. 1. scalar or VVVF and 2.
Vector or position control.In scalar control method we use
normal drives or cyclo-converters to control the voltage and
frequency for speed variation. but in vector mode we take
the feedback of position of the rotor and accordingly we
fire the device.It is the most complex technology and is
used only for precision speed control systems.

Answer / paddu241

frequency control

Answer / g senthilkumaran

Using scalar control, also called "volts per hertz" control
or v/f control, a drive essentially acts as a power supply
of a selected frequency and proportional voltage. At a
given speed, the motor performs much as it would when
supplied by utility power. For each frequency setting,
motor operation is governed by a torque Vs speed curve that
is similar to the torque Vs speed curve that governs
utility power operation.

if the back emf eqution for dc motor EB=(QPNZ/60A) THEN what is the value of A for PMDC MOTOR OR how can dicide the value of "A"

2 Answers   BSL,

---

How to select the different contactors ( starter combination) for different AC motors? what about fuse cappacity 4 different motors too?

2 Answers   Equate,

---

What is control system?

0 Answers  

---

Explain why the Voltage drop will happen in 3 Phase line?

3 Answers  

---

why wire sizes are 3/29 or 7/29 and why not wire sizes are 2/29 or 6/29?

0 Answers   OGDCL,

---

---

an amazing situation was faced when an alive distribution panel with 415 volts and carrying almost 200Amps has become short and this metal cubical showing 220 volts against neutral and earth. to redress any confusion i checked the panel with help of single 200watts test lamp which also glowing with max.intensity b/w neutral & metal body of DB. amazing situation is that i hold the DB firmly more than once with necked foot means without insulated shoes but not received any electrical shock. whereas our all running gen sets neutral points also proper grounded and this short DB was completely earthed , this is beyond my understanding . any body explain how is it possible . our running gen set neutral also grounded firmly

1 Answers  

---

How can calculate the earthing strip of Copper/GI for rating of 30kV,discharge current 10KA Lightning arrester.

0 Answers   Raychem RPG,

---

In single phase ac ups supply when current is measured with tong tester neutral current is found more than phase current.What is the reason?

0 Answers  

---

EXPLAIN THE ESSENTIAL FACTORS WHICH INFLUENCES THE CHOICE OF SITE FOR A HYDRO ELECTRIC POWER PLANT

0 Answers  

---

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.

1 Answers   Jindal,

---

1.protection used in transformer ? 2.Why breather called breather ? 3.Working of conservator tank.? 4.Speaker of parliament ?

4 Answers   Power Grid,

---

how to check the insulation for motor using megger?

2 Answers   GSK,

---