What is difference between 3 point and 4 point starter
- 1 Answers
- 3668 Views
- Genco, Kaltec, TATA, I also Faced
- E-Mail Answers
Answer Posted / udit
3pt starter : No volt coil and field coil are in series .
4 pt starter : No volt coil and field coil are in parallel.
To get speed above rated speed we use field weakening control as speed increases if we reduce flux. So to do it we reduce field current . In 3pt nvc and field are in series so nvc current also reduces hence the electromagnetic force reduces and magnet releases the handle and motor gets turned off. Thus we cannot use 3 pt starter for field weakening control hence we use 4 pt starter .
If there is field failure (field coil open circuited)then speed becomes dangerously high and motor can damage. To avoid this if field C oil is in series with nvc then whenever there is field failure the current in nvc also becomes zero and motor is turned off .hence no damage to motor. This is advantage of 3pt over 4pt.
Nvc is no volt coil
| Is This Answer Correct ? | 1 Yes | 0 No |
Post New Answer View All Answers
How efficiency of thermal plant can be improved?
how can i get an electrical c-certificate?
why not starting switch first connect in direct on line starter?????
Why reactive power is needed in a power system? How is it being absorbed or delivered by alternators? For reactive power control we are changing excitation but reactive power absorbing or delivering related to stator. How these two are interlinked? i want a detailed explanation with necessary expressions and figures?
What are the commonly used schemes for the bus zone protection?
In HI POT test what is reason for applying the AC VOLTS and DC VOLTS in different applications what is the nessesity for this ?
Please tell me the power flow from pmg to main rotor of an alternator (Including AVR unit)?
Is there a possibility to use such a treshold voltage for the NMOS part of a CMOS circuit that during the switching it will start conducting only after the PMOS part will be already closed, by this eliminating the leakedge current? Please note, I'm not asking about the well bias in standby mode, but about the "antileakedge" measures during normal operation.
How to Preparation of online test
Should power factor be low or high?
what is vA rating and class of a ct.
single phase power supply give to separate one steel coup with water, what reaction create
Differentiate between kirchhoff’s first law and kirchhoff’s second law?
Explain thin film resistors and wire-wound resistors
While performing stability test of differintial cts how to know the voltage and current on both side of the transformer?
