There are two convolutions in each section, the adjacent ends of neighboring sections being soldered to radial lugs projecting from the commutator bars.
An end view is simply a view showing the arrangement of the armature inductors and connections looking from the front or commutator end.
There will be as many brushes as poles, and they will be situated symmetrically around the commutator in regular order and at angular distances apart equal to the pole pitch.
Sparking, if allowed to continue, will injure the brushes and commutator segments.
Commutation begins; current flows up both sides of the armature, uniting at S and flowing to the brush through commutatorsegment 1 as indicated by the arrow.
The commutator is constructed of bars of hard drawn copper of uniform size and shape, supported and clamped at either end between beveled rings and securely seated on the commutator drum.
The brush is fed through an accurately broached slot by a spring which maintains uniform pressure against the commutator throughout the wearing length of the brush.
In the Siemens winding, the end of the wire used at the start is to be connected to the first commutator bar, but must be fastened to the armature core out of the way so as not to interfere with the winding of the coils.
The commutator is longer than the commutators on machines of equal capacity at higher voltages, and as a rule the commutator segments are thicker and fewer in number.
Commutator segments are often made with the washers E, projecting beyond the ends, but such construction reduces the effective length of the commutator, therefore the under cut form of bar is preferable.
The collars are insulated with mica from the segments and they are held in place by nuts upon the commutator shell or by bolts passing from end to end under the segments.
K is a commutator for reversing the direction of the magnetizing current, and G a galvanometer for measuring it.
Inside the torsion-head is a commutator for automatically reversing the current, so that readings may be taken on each side of zero, and the arrangement is such that when the torsion-head is exactly at zero the current is interrupted.
F to D, while at the same time the commutator K is rapidly worked, a series of alternating currents of gradually diminishing strength being thus caused to pass through the magnetizing coil.
Hence, by rocking the brushes around the commutator the pressure at the terminals of the machine may be varied and regulated as required.
During the first half of the revolution the current flows in the direction A B, out through segment F of the commutatorand brush M, returning through brush S and segment G, figs.
The commutator segments are drop forged in the smaller, and hard drawn in the larger sizes.
At this instant the brushes M and S pass the gaps between the commutator segments, thus reversing contact with the segments, and causing the current in the external circuit to remain in the same direction.
The ends of each conducting loop or coil must be connected with the commutator segments in a certain order to correspond with the type of winding.
In the construction of the motor, continuous motion in one direction is obtained by the use of a commutator (Section 310); in the construction of a dynamo, continuous current in one direction is obtained by the use of a similar device.
When very powerful motors are necessary, the field magnet is so arranged that it has four or more poles instead of two; the armature likewise consists of several portions, and even the commutator may be very complex.
As armature, commutator, and shaft rotate, the brushes connect first with one segment of the commutator and then with the other.
Electrical connections are so arranged that when the commutator is tilted to the right, the transmission is down-hill, when tilted to the left, up-hill.
See that it does not lack good lubricating oil, and do not let its commutator get dirty.
The commutator should assume a glossy chocolate brown color.
The connectors between the armature winding and the commutator bars, as shown in fig.
Diagram of ring armature in alternating field illustrating the principles of commutator motors.
In this type, the winding is tapped at three points 120° distant from each other, and leads connected with the corresponding commutator segments.
As a rule the brushes are lifted off the commutator when the armature is short circuited, so as to prolong their life.
In case the shaft become damaged or worn, it can be readily pressed out and replaced without disturbing the commutator or windings.
Armature of Wagner single phase repulsion-induction commutator motor as seen from the commutator and rear ends, showing the vertical commutator and type of governor employed on the smaller sizes.
Since the armatures are identical, and as the similarly placed windings are passed through identical magnetic fields, one winding with proper connections to the slip rings and commutator will do for both.
This class of commutator motor is about the simplest of the several types belonging to this division.
The commutator is of the regular horizontal type and the brushes remain in contact all the time.
The cost of the additional number of commutator bars and connectors as well as the added mechanism.
The change in commutator voltage for constant collector ring voltage is in virtue of the property of rotary converters that the ratio of these two voltages is a function of the width of the pole arc.
They were soon found to work much better with four, and finally still better as the number of commutator bars (or coils) was increased, up to a practical limit.
The first dynamos were constructed with two commutator bars.
The commutator is 20 inches long, and has sixty-four parts.
A space of one millimeter is sufficient to bring the commutator to a horizontal position and to cause the electric alarm to ring continuously.
The surfaces of the brushes that bear on the commutator should be inspected to see that they are clean, and that the entire surfaces make contact with the commutator.
When the brushes are "dressed" with sandpaper, however, they will not fit the grooves, and the commutator should be turned down in a lathe until the grooves are removed.
Brushes bearing on wrong point of commutator (to set brushes properly, remove all outside connections from generator, open the shunt field circuit, and apply a battery across the main brushes.
A commutator may have grooves cut in by the brushes.
The brushes should be lifted from the commutator while this is being done.
Watch for "high mica," which means a condition in which the insulation between the segments projects above the surface of the commutator, due to the commutator wearing down faster than the insulation.
In turning down the commutators of high speed motor-generators, special fittings should be made by means of which the armature may be mounted in its own ball-bearings while the commutator is turned down.
In case of generators using other kinds of regulation, loose connections, dirty commutator and brushes, etc.
If the commutatoris rough it may be made smooth with fine sandpaper held against it while the generator is running, and the brushes are lifted.
See that there is enough lubricating oil in the bearings, but that there is not too much oil, especially in the bearing at the commutator end of the generator.
A change in the charging rate, cleaning of the generator commutator or cutout contact points, if done in time, will often keep everything in good shape.
High mica, loose brush spring, or a commutator which has been turned down off-center may cause the trouble.
That is to say, if it be supplied with direct current of the proper voltage at its commutator end, it will run as a direct current motor and deliver alternating current to the collector rings.
Oscillogram showing the direct current pressure of a 25 cycle rotary converter (below), and (above) the pressure wave taken between one collector ring and one commutator brush.
How can the commutator speed be kept within reasonable limits, other than by reducing the width of the commutator bars?
The armature resistance is the resistance of the armature winding of the dynamo, between the commutator bars upon which press the positive and negative brushes.
The friction of the brushes can very conveniently be determined next by lowering them on the commutator and giving them the proper tension.
The contact breaker consists of a commutator having an ebonite or insulating segment and two brushes.
A marked advantage of this type of construction is the accessibility of the commutator for adjustment of the brushes, etc.
Motor converters are occasionally used on high frequency systems, as their commutating component is of half frequency, and thus permits better commutator design than a high frequency converter.
One slip ring is connected to one terminal of the source, the other to the voltmeter, and the commutator to the condenser.
The commutator is peculiar, consisting of only three segments of a copper ring, while in the simplest of other continuous current generators several times that number exist, and frequently 120!
Besides this, the commutator is sustained by supports carried in flanges upon the shaft, which flanges, as an additional safeguard, are coated all over with hard rubber, one of the finest known insulators.
It may be stated, without fear of contradiction, that no other commutator made is so thoroughly insulated and protected.
This consists of a peculiar magnet attached to the frame of the generator, and the movable armature of which has connections to the supports of the commutator brushes for controlling their position.
Four slit copper springs, called commutator brushes or collectors, are allowed to bear lightly upon the commutator when it revolves, and serve to take up the current and convey it to the circuit.
From the brushes the current is taken to a commutator worked by a lever, which switches resistance frames placed under the car, in or out, as may be desired.
The commutator and brushes, in consequence, after weeks of running, show scarcely any wear.
The threecommutator segments virtually constitute a single copper ring, mounted in free air, and cut into three equal pieces by slots across its face.
The same lever alters the position of the brushes on the commutator of the dynamo machine, reversing the direction of rotation, in the manner shown by the electrical hoist.
This feature, as well as the fact that the commutator can be oiled to prevent wear, saves attendance and greatly increases the durability of the wearing surfaces, while the commutator brushes are maintained in the position of best adjustment.
These commutator brushes are carried by movable supports, and their position is automatically regulated so as to control the strength of the developed current--a feature not found in other systems.
The commutator short-circuits the armature coils in succession in the proper positions to utilize the repulsive effect set up by the currents which are induced in them by the alternations in the field coils.
The commutator is arranged to short-circuit each of these coils in succession, and twice in a revolution, and for a period of 90-degrees of rotation each.
Plainly visible on its shaft is a commutator to which the electric current from a dry cell is sent.
If the brushes rest upon rings upon the axle they send forth alternating current--but if the brushes rest upon commutator bars they send forth direct current.
For what services is the commutator type meter used?
A commutator is provided to easily make the change from one range to the other.
If there be two sets of reed, the one commutator may be connected to change both.
The complication of commutator and brushes, and the fact that the friction of the brushes is likely to affect the accuracy of the meter.
These are not commutator brushes, but are merely wiping brushes to take the current from the turning parts.
All dynamos originally make this kind of current, but the commutator and brushes in the direct current machine change the output method only.
The whole of the connections here indicated can be quickly made by means of a cross-bar commutator or switch, which is supplied with the machines in cases where such changes are likely to be required frequently.
The terminals of the fuze are connected to the binding screws of the balance, the commutator N and galvanometer A being connected up in circuit.
These currents, almost as soon as they are induced, are collected by terminal rollers or brushes B, usually the latter, placed in contact with the commutator in the position which gives the strongest current.
The ends of these wires are brought to a commutator and connected to the segments either by screws or by soldering.
The position of the brushes yielding the least spark at the commutator is that giving the highest intensity of light in the electric arc.
The position giving the strongest current gives also the least spark, so that when there are no sparks at the commutator the best lighting effect is produced.
Bright sparks should never be allowed to appear at thecommutator and brushes, as sparks result from a rapid burning of the metallic parts.
A commutator or switch plate is an apparatus by which the direction of currents may be changed at will, or by which they may be opened or closed.
The commutator should, while in motion, be freely oiled, to prevent the brushes wearing away too rapidly.
These pieces of insulation are mounted in the corners of the armature support, at the commutator end, by means of two small screws in each.
The position of the commutator and brushes should be such that the brushes move from one segment to the other when the ends of the armature are directly in line with the ends of the permanent magnet.
The armature winding is not to be put on the core until the commutator has been constructed and mounted on the shaft.
Place the commutator on the shaft so that the projections on the pieces of brass are toward the armature core and the spaces between the ends of the pieces occupy the position relative to the cores, shown at A, Fig.
Illustration: Details of the Armature Laminations and the Commutator Segments, and the Method of Mounting Armature Core and Commutator (Fig.
Mount the brushes on these pieces so that their free ends bear on the commutator exactly opposite each other.
Illustration: Detail of Parts Showing Wire Connections and Model in Flight around the Central Axis] The commutator rings were made of heavy brass strips, fastened to a round piece of wood which was attached to the metal standard.
The wires from the current supply were connected to the commutator rings.
The gong and commutator were removed and the magnet placed in the position shown in the sketch.
The commutatorconsists of three pieces of thin sheet brass similar to that shown at B, Fig.
The beam was attached to the skate wheel with two small bolts which were insulated and carried two brushes as commutator contacts.
It is best to have these ends terminate on the commutator side of the frame.
The armature wire (C) has one end attached to the positive commutator terminal and the other end of this wire is attached to the negative terminal.
The commutator is made of a split tube, the parts so divided being insulated from each other, and in Fig.
A generator or motor wound in such a manner that one of the commutator brush connections is joined to the field magnet winding, and the other end of the magnet winding joined to the outer circuit.
To these arms the brushes (21) are attached, so that their spring ends engage with the commutator (12).
It is to be observed that a dynamo with brushes on the commutator is not necessarily a Brush dynamo as a good many people seem to think, the latter being named after its inventor, Mr. Brush.
The brushes of copper wire which collect the current of the exciter dynamo, and others of similar pattern, must be placed so that the ends press on the commutator as shown in Fig.
The cover C on top of the motor at one end closes an opening through which access to the commutator brushes is obtained.
The commutator is secured to the armature shaft, and the brushes through which the current enters and leaves are held stationary; keeping this fact in mind, it can be seen at once that in Fig.
To explain clearly the way in which the commutator reverses the current in one coil at a time it will be necessary to make use of a diagram illustrating what is called a ring armature.
The flanges H and I are simply shields to prevent oil, grease, or even water, if it should pass through the bearings, from being thrown upon the commutator or armature.
The armature is marked A, the shaft B, and the commutator C.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "commutator" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: device; generator; parts; relay
