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Why the value of armature resistance is low?
Because it is made of pure wire with nothing beyond its length and interaction with its neighboring wires to create resistance
What is the required resistance in mega ohm when performing megger?
Normally the megger should be selected based on the following criteria. 1.Voltage rating of the megger 2.Range of the megger value 3.Manual - Hand operated analogue type 4.Auto- Digital Megger To measure the insualtion resistance of Motor (LV Motors) Up to 500 V/1000 V Megger is sufficient To measure the insualtion resistance of Motor (HV Motors) Up to 5000 V can be choosen Normaly the range starts from 0.5 to Infinity meg value in the analogue However in digital the based on the least count /range of the instrument we can able to measure the insualtion value.
Name the three basic methods that are used to vary the speed of a DC motor?
speed of a dc motor can be varied by mainly two methods:- 1)field control method 2)armature control method further , field control method can be divided in 3 parts:- 1)field rhestat control method---speed variation is acomplished by means of a variable resistance inserted in series with shunt field 2)reluctance control method---by changing the reluctance of magnetic circuit by choosing right material.. 3) field voltage control method-requires variable field voltage supply. and armature control method can be divided in 3 parts :- 1)armature resistance control---variable resisitance connected in series with armature 2)shunted armature control. 3)armature voltage control. ------------mrityunjay pandey (kiit university ,btech 2nd year)
What should the value of the resistance box for a 5 hp slipring induction motor?
its depends upon rotor voltage and current
How you determine the starting and running winding of a capacitor start single phase motor?
I think the resistance value of starting winding is less than the running winding of the single phase motor
How do you measure the resistance of a motor?
we can measure the resistance of the motor by using voltmeter ammeter method of by directly using a multimeter across the armature terminals of the motor in voltmeter ammeter method we should use a less value of dc voltage to find the resistance
Explain the necessity for the use of a starter with a dc motor?
In its simplest form, the starter of a dc motor is a variable resistance in series with the armature circuit of dc motor to reduce the high starting current so that the armature winding does not get overheated and burnt while the motor isgetting started. As the rotating armature of dc motor picks up speed, the starter resistance is gradually reduced so that the motor is able to attain its full speed when the starter is not expected to offer any additional resistance in series with the armature winding of the dc motor. At full speed the motor starts running normally, of course, without the help of starter. In other words, the starter offers resistance to armature current during starting of dc motor only. Under normal working condition of dc motor , the starter is electrically out of armature circuit of the motor. The starter protects the armature of dc motor from getting damaged. The electromotive force (emf) induced in the armature winding during starting builds up from zero value to max value to restrict the armature current within the permissible value at full speed. As the speed of armature/motor build up, armature induced emf also starts building thus reducing the role resistance offered by the starter, hence requiring it to gradually reduce as the motor picks up full speed.
Why the value of armature resistance is low?
Because it is made of pure wire with nothing beyond its length and interaction with its neighboring wires to create resistance
Is four point starter is applicable to compound motor?
Yes! · To accelerate the motor to the rated speed · To limit the starting current in the armature to a safe value · To disconnect the motor in case of a supply failure or overload
What is the required resistance in mega ohm when performing megger?
Normally the megger should be selected based on the following criteria. 1.Voltage rating of the megger 2.Range of the megger value 3.Manual - Hand operated analogue type 4.Auto- Digital Megger To measure the insualtion resistance of Motor (LV Motors) Up to 500 V/1000 V Megger is sufficient To measure the insualtion resistance of Motor (HV Motors) Up to 5000 V can be choosen Normaly the range starts from 0.5 to Infinity meg value in the analogue However in digital the based on the least count /range of the instrument we can able to measure the insualtion value.
Name the three basic methods that are used to vary the speed of a DC motor?
speed of a dc motor can be varied by mainly two methods:- 1)field control method 2)armature control method further , field control method can be divided in 3 parts:- 1)field rhestat control method---speed variation is acomplished by means of a variable resistance inserted in series with shunt field 2)reluctance control method---by changing the reluctance of magnetic circuit by choosing right material.. 3) field voltage control method-requires variable field voltage supply. and armature control method can be divided in 3 parts :- 1)armature resistance control---variable resisitance connected in series with armature 2)shunted armature control. 3)armature voltage control. ------------mrityunjay pandey (kiit university ,btech 2nd year)
How would you extend the range of a voltmeter and ammeter?
if we would like to expand the range of voltmeter we should change the voltmeter resistance even to be appropriate . we should use a variable resistance to control of its value . I would extend the range of a voltmeter by adding resistance in series with it. I would extend the range of an ammeter by connecting resistance in paerallel with it.
What result should you obtain when you do megger tests for motor?
we will get its insulation resistance value wchich should be greater than 200Mohms
What should the value of the resistance box for a 5 hp slipring induction motor?
its depends upon rotor voltage and current
What happens to the value of insulation resistance of a cable when the cable gets older?
Insulation resistance should be approximately one megohm for each 1,000 volts of operating voltage, with a minimum value of one megohm. For example, a motor rated at 2,400 volts should have a minimum insulation resistance of 2.4 megohms.
How you determine the starting and running winding of a capacitor start single phase motor?
I think the resistance value of starting winding is less than the running winding of the single phase motor
What is the value for resistance 1100 ohms?
The number of ohms is, precisely, the value of the resistance.
