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Principles of Energy Conversion
Published in Hamid A. Toliyat, Gerald B. Kliman, Handbook of Electric Motors, 2018
Hamid A. Toliyat, Gerald B. Kliman
Most commutators are made from copper bars with some form of insulation between bars and a means of mechanical clamping to prevent centrifugal forces from moving the commutator bars radially. The clamping method must be designed so as to ensure that the bars are held firmly in position under loading from radial forces, axial forces during and after assembly, and thermally induced forces. The difficulty is compounded by the fact that any metallic clamping device must be insulated from the commutator to prevent reporting between adjacent bars. Figure 6.10 shows one form of commutator construction for larger motors, that is, motors above a few horsepower.
Generators and motors
Published in David Wyatt, Mike Tooley, Aircraft Electrical and Electronic Systems, 2018
Therefore, the current in each of the armature conductors must be reversed as the conductor passes between the north and south magnetic field poles. The commutator acts like a rotating switch, reversing the current in each armature conductor at the appropriate time to achieve this continuous rotary motion. Without the presence of a commutator in a DC motor, only a half turn of movement is possible!
Applied Electrical and Mechanical Science
Published in Mike Tooley, BTEC First Engineering, 2010
Therefore, the current in each of the armature conductors must be reversed as the conductor passes between the North and South magnetic field poles. The commutator (see Fig. 4.24) acts like a rotating switch, reversing the current in each armature conductor at the appropriate time to achieve this continuous rotary motion. Without the presence of a commutator in a d.c. motor, only a half turn of movement is possible. Figure 4.25 shows how the commutator acts as a rotary switch that periodically reverses the direction of current flow ensuring that the motor torque continues to turn the rotor in the same direction. Fleming’s left-hand rule can be used to the direction of rotation at any instant.
A New Metatheorem and Subdirect Product Theorem for L-Subgroups
Published in Fuzzy Information and Engineering, 2018
If L is a complete dense chain, then the convolutional extension introduced by Tom Head provides a special instance of commutative natural extension. Moreover, it is easy to verify that the function Rep commutes with the natural extension of the unary operation defined by . That is if , then Below we provide some more examples of commutative natural extensions. Let a binary operation be defined by . Then the natural extension of to is given by and we write . This natural extension is commutative as Let a binary operation be defined by , where is the commutator of A and B. Then the natural extension of this binary operation to is given by and we write Moreover, it is a commutative natural extension provided L is a dense chain (see Proposition 3.5).Let a binary operation be defined by , where is the commutator subgroup of A and B. Then the natural extension of this binary operation from to is given by and we write . Note that this natural extension is a composition of the natural extension of the of the unary operation on given by and the binary operation on given by . As in a dense chain the operations and are commutative, it follows that the given binary operation is commutative provided L is a dense chain.