Problem 102-1    Source:   Example 7-3 - page 447 - CHAPMAN, Sthephen J. -    Book: Fundamentals of Electric Machines - 5th Edition - Ed. McGraw-Hill - 2013.

A duplex armature with lap winding is used in a six-pole DC machine with six sets of brushes, each one spanning two segments of the switch. There are 72 coils on the armature, each with 12 turns. The flux per pole of the machine is 0.0039 Wb and it is turning at 400 rpm. Find:

a) how many current paths are there in this machine?

b) what is the induced voltage E_A?

Problem 102-2    Source:   Adapted from Example 7-4 - page 448 - CHAPMAN, Sthephen J. -    Book: Fundamentals of Electric Machines - 5th Edition - Ed. McGraw-Hill - 2013.

A DC generator of 12 poles has a simplex wave-winding armature containing 144 coils of 10 turns each. The electrical resistance of each turn is 0.011 Ω. Its flux per pole is 0.05 Wb and it is rotating at a speed of 200 rpm.

a) How many current paths are there in this machine?

b) What is the induced voltage E_A?

c) What is the effective armature resistance of this machine?

Problem 102-3    Source:  Problem prepared by the website author.

Be an armature winding of a 4-pole DC machine, lap winding, having 960 active conductors and rotates at a speed of 1,200 rpm. Since the flux per pole is equal to 0.07 Wb, find:

b) the number of paths for the electric current;

a) the voltage induced in the armature winding.

Problem 102-4    Source:  Problem prepared by the website author.

A DC machine has wavy armature winding, 6 poles, with 20 conductors per slot. Assuming that the machine has 48 slots and the induced voltage in the armature is 640 V at 600 rpm, find:

a) the number of active conductors;

b) the magnetic flux in that machine per pole.

Problem 102-5    Source:   Adapted from example 2-1 - page 73 - CHAPMAN, Stephen J. -    Book: Fundamentals of Electric Machines - 5th edition - Ed. McGrawHill - 2013.

We want to obtain a DC machine, 4 poles, which generates an armature voltage E_A = 600 V when operating at speed of 800 rpm, using corrugated winding. The flux at the poles is 0.075 Wb. Find:

a) the machine constant K_a;

b) the number of active conductors, Z, in the rotor.

Problem 102-6    Source:  Problem prepared by the website author.

A coil with 20 turns in square shape and 250 mm on a side, is mounted on a cylinder 150 mm in lightning. The cylinder operates at a speed of 1200 rpm in a uniform field of 0.8 T. Find the maximum value of voltage induced in the coil.

Problem 102-7    Source:  Problem prepared by the website author.

A machine with 6 poles generates an armature voltage E_A = 300 V when operating at a speed of 1,200 rpm. The number of slots in the armature is 25 and the flux per pole is 0.02 Wb. The armature winding is of the wavy type with multiplicity 2. Find:

a) the machine constant K_a;

b) the number of active conductors, Z, in the rotor;

c) the number of conductors per slot.

Problem 102-8    Source:  Problem prepared by the website author.

A machine has 456 slots in the rotor. Answer whether the following windings are possible:

a) simplex winding with 6 poles;

b) triplex winding with 6 poles;

c) duplex winding with 8 poles;

d) simplex winding with 10 poles.