Figure —Armature reaction. Now you have two fields — the main field, view A, and the field around the armature coil, view B. View C of figure shows . These interpoles, being midway between main poles, are just opposite the The interpole windings are connected in series with the armature. Stator of a DC machine. ▫ Stator is the stationary part. ▫ Main poles as field winding. ▫ Further windings. ▫ Interpole. ▫ Compensation eliminate unwanted effects.
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The field strength is independent of the armature current. Gramme-ring wound armatures are seldom used for this reason. To limit armature current until counter EMF builds up. To avoid the commutation difficulty actually encountered in old-style generators, narrow poles called interpoles or commutating poles are used, as indicated in Fig.
Such a diverter is called intsrpole inductive shunt. If the ordinary resistance diverter were used, a sudden surge of current caused by a sharp increase in load would not divide between interpooe interpole path and the diverter path in inverse proportion to their respective resistances; but, because of the high reactance of the interpole path, a disproportionately large portion of the surge current would flow through the diverter.
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged. It is not necessary to shift the brushes when wondings is an increase or decrease in load.
Excessive current will flow when DC voltage is first applied unless current is limited in some way. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The DC motor is reversed by reversing the direction of the current in the armature. The proper division of surge current can be obtained by inserting, in series with the interpole shunt, a conductor wound around an iron core to form an inductance just equal to that of the interpole coils.
Like poles of the armature and field then repel each other, causing armature rotation to continue. Motor will slow down. The interpole windings are connected in series with the armature windings, and therefore their correction ampere-turns increase or decrease in the same proportion as do the distorting ampere-turns of the armature. The field strength varies with changes in armature current. Its starting torque is greater than other types of DC motors.
As the armature begins to turn, counter EMF increases; and, since the counter EMF opposes the applied voltage, the armature current is reduced. By winding the armature in a way that places the entire coil where it is exposed to maximum flux.
COMPENSATING WINDINGS AND INTERPOLES
What is the purpose of starting resistors? By reversing either field or armature connections. Pages through In practice the interpoles are made stronger iinterpole just sufficient to neutralize the armature flux, in order to aid in the reversal of current in the coils being commutated. The device to be driven by the motor.
All about EEE: What is the function of interpoles and how are its winding connected?
If both are reversed, rotation will continue in the original direction. The speed and torque characteristics are a combination of interpol desirable characteristics of both series and shunt motors.
Winvings are the Gramme-ring and the drum-wound types. What current flows in the interpole windings? Only outside of coils cut flux inefficient. It must have a load connected to avoid damage from excess speed. The armature poles are attracted to field poles of opposite polarity, causing the armature to rotate.
If their polarities be made the same as those of the armature poles opposite to them, and if their strength be made equal to that of the armature poles, then the distortion of the main field at the commutating point, as in Fig. See the editorial for more information It may then be removed after counter EMF has been built up. Interpoles and compensating windings are used to reduce the effect of armature reaction on motor operation.
High torque turning force at low speed. There wineings no differences. It is very difficult for a designer to calculate the exact number of turns to be placed on the interpoles, and it is sometimes necessary to connect an adjustable diverter around the interpole windings to permit shunting of a part of the total armature current around those coils.
This EMF opposes the applied voltage, and limits the flow of armature current. Controlling the starting resistance in a DC motor is accomplished either manually, by an operator, or by any of several automatic devices. Kimberly To avoid the commutation difficulty actually encountered in old-style generators, narrow poles called interpoles or commutating poles are used, as indicated in Fig. LOAD on a motor is the physical object to be moved by the motor.
Such an improper division would cause the interpole field to fail to rise in proportion to the armature current to be commutated, and would probably cause the commutator to flash over at the brushes.