Why is starter necessary for a three-phase induction motor?
Answer Posted / farha
A starter is needed for a three phase induction motor
because at the time of starting, if induction motor is
started directly, it will draw large amount of current
which causes damage to adjoining equipments.
Thus, a starter is needed in order to limit the starting
current.After the motor has started at reduced starting
current and hence reduced voltage, the connections are
diverted towards the mains supply so that now, the motor
can run at higher starting current and voltage.
Four types of starting methods are employed:
1.Star-Delta
2.Auto transformer method
3.Primary resistor starting.
4.Direct On-line.
Low rating upto 7 H.P motors can be started directly.
| Is This Answer Correct ? | 608 Yes | 51 No |
Post New Answer View All Answers
How is efficiency of DG set calculated? At many places I found the efficiency to be mentioned in percentage. But at some other places I found kWH/ litres. I want to know how dimensionless percentage value is arrived at?
What is effect on in zone and out zone fault if CT chosen for phase side is Vk/2<5mA and Neutral side is Vk/2<15mA on REF protection of Transformer
why wire sizes are 3/29 or 7/29 and why not wire sizes are 2/29 or 6/29?
We have drive feeding an output contactor for a 5000 hp motor @ 5kV application. The motor FLA is 629amps x 1.25% service factor = 786.25 amps The cable that we current have in place between the drive and the output contactor is 350kcmil- MV-105 (parallel cables). Per the NEC table 310.60 (C) (69). This show the cable ampacity is at 615 amps per cable for a rating of 1230 amps. We have derated the cable for the cable tray and the multiple cables application and our calculations show that after the correction factor factor we are at 922amps. 1230 amps x .75% correction factor factor = 922.5 amps. The customer is driving us to then use another safety factor of .25% off of the already derated cable. Can you please provide a longhand calculation for your solution on this application?
How should i design a 1ph & 3 ph transformer. Kindly let meknow all steps and formulaes related to design from scratch.
what is the chemical name and formula of refrigarent R-134a.
Where can I get CPWD electrical specifications & Shedule of rates? Please help me
How phase displacement change in the over current relay coils.
Explain RLC circuit?
when we have to purchase the transformer by own i.e how much load will preferred HT connection?
Explain the operation principle, advantages and disadvantages of the following converters: a) A 12 pulse converter b) A Switch-mode inverter c) A thyristor inverter
does the Trivector Meter of three phase automatically takes care of the low power factor and gives the reading accordigly or it does not take care of the Power factor while giving the readings please explain
what is basic difference betmeen normal & flame proof motor??
What is the operating principle of turbo-generator.
What is earth?