91. What are the essential differences between arc welding and
resistance welding ?
2. Essential differences between brazing and fusion welding?
3. Explain the basic principles of arc welding processes
4. Why arc welding is called stick welding
5. can arc welding be used to join plastic materials?
explain
6. What is a flux
7. What are the purposes of using flux?
8. Flux can be used in which joining processes
9. What are the disadvantages of using flux
10....
A 5-kW, 250-V shunt motor has an armature resistance of 0.1 ?
and a field-circuit resistance of 80 ?. When the motor is operating
at rated voltage, the speed is observed to be 1200 r/min when the
machine is loaded such that the armature current is 30 A. In order
to protect both the motor and the dc supply under starting
conditions, an external resistance will be connected in series with
the armature winding (with the field winding remaining directly...
The resistance of a starter for a 200-V, shunt motor is such
that maximum starting current is 30 A. When the current has
decreased to 24 A, the starter arm is moved from the first to the
second stud. Calculate the resistance between these two studs if
the maximum current in the second stud is 34 A. The armature
resistance of the motor is 0.4 Ω.
ANSWER [1.334 Ω]
A shunt motor has a supply voltage of 200 V and
armature resistance of 3.6 Ω. At certain torque the motor run at
speed = 1200 R.P.M and take a current of 10 Amp from the supply and
its field current is 0.5 Amp. Find starting torque, no-load speed,
and the load torque when the current supplied by the supply is 5
Amp.