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Traditionally there are two methods to limit starting current at the design stage:
- Increase the rotor resistance by using smaller section of rotor bars. No. of bars can also be reduced but this will hamper smooth rotation of the motor.
- Use deep rotor bars or double cage rotor. Both the methods are functionally same but constructionally double cage is more complicated.
What else can I help you with?
What are the reasons for connecting resistance in the rotor circuit when starting wound rotor induction motors?
To limit the starting current in slip ring induction motors.
What is the advantage of the capacitor-start induction-run motor over the resistance-start induction-run motor?
A capacitor-start system will limit the current drawn by an induction machine by correcting the devices poor power factor during the start up. This limits the current needed to start the device without using any real power. A resistance-start system will limit the starting current by drawing current unto the resistor instead of the induction machine. The real power used by the resistor is turned into heat and lost. A capacitive-start system will use no real power and will not create excess heat, it will be more expensive to initially purchase.
FCMA starter principle and working during starting induction motor?
The FCMA (Field Control Motor Arrangement) starter principle involves controlling the field current to manage the starting torque and speed of an induction motor. During startup, the motor is initially supplied with reduced voltage to limit the inrush current, and the field current is adjusted to ensure smooth acceleration. As the motor approaches its rated speed, the field current is gradually increased to optimize performance. This method enhances efficiency and prolongs the motor's lifespan by preventing mechanical and electrical stress during startup.
Why the armature rheostat of dc is motor kept at maximum resistance position?
It isn't. It is only kept at maximum resistance when the motor is not running. That is done to limit the starting current.
What is the function of Resistance?
A series DC motor has to have a starting resistor to limit the current flow before the speed builds up.
What is the need for starters in an dc machine?
To limit the starting current, which can be significantly larger than the running current -large enough to overheat the machine's winding and , possibly, causing insulation failure.
Why is hot start and cold start term used in 3 phase induction motors?
In a 3 phase induction motor, particularly the larger units, hot start and cold start refer to the temperature of the motor when starting. Hot start is usually a restart after coasting to a stop. Cold start is an initial start, after not having run for a relatively long period of time. This is important because there is usually a limit on the number of hot starts that are allowed in a certain period of time. This is due to the fact that these motors pull more current starting than when they run, and if you start them too often they can overheat.
Do resistors limit current or voltage in an electrical circuit?
Resistors limit the flow of current in an electrical circuit.
Can a capacitor be used as a fuse to limit overload current?
No, a capacitor can not be used as a fuse to limit an overload current condition.
Why are no starting components needed on three-phase motors?
Yes, by using a DOL Starter, which gives a controlled "soft-start" for the motor even though it is always connected in delta configuration.In this type of starting a 3-phase motor, full voltage is applied to the motor through relays and contactors. Its is the most common type of 3-phase motor starter used.DOL means Direct On-Line starter.
What will happen if field rheostat of dc shunt motor is kept at maximum position while starting?
First remember this rheostat is connected in series with the armature to increase the total resistance to limit the starting current, thus achieving max starting torque from the motor
Can a capacitor limit current in a circuit?
No.
