March 28, 2019 posted by

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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There are no differences. Such a diverter is called an inductive shunt. It is not necessary to shift the brushes when there is an increase or decrease in load.

LOAD on a motor is the physical object to be moved by the motor. When the armature current is reversed, the current through the interpole is also reversed. Unloaded operation of large machines is dangerous. Motor will slow down. 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.

The armature poles are attracted to field windigns of opposite polarity, causing the armature to rotate.


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. Shunt-motor speed varies only slightly with changes in load, and the starting torque is less than that of other types of DC motors. They remain in that position for all conditions of load.


As the load varies, the interpole flux lnterpole, and commutation is automatically corrected as the load changes. Increasing the armature circuit resistance decreases motor speed. Nearly all DC motors have drum-wound armatures. Interpoles and compensating windings are used to reduce the effect of armature reaction on motor operation.

Direction of armature current, and direction of magnetic flux in field. The inductance interpile the coil tends to retard the reversal of the coil current by generating a prolonging voltage and the interpoles must have sufficient additional strength to neutralize this inductive voltage.

The following information provides a summary of the main subjects for review. When its speed is reduced by a load, the series motor develops greater torque. High torque turning force at low speed.

The field strength is independent of the armature current. It may then be removed after counter EMF has been built up.

Kimberly To avoid the commutation difficulty actually encountered in old-style generators, narrow windingz called interpoles or commutating poles are used, as indicated in Fig. Like poles of the windimgs and field then repel each other, causing armature rotation to continue. 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.

What is the purpose of starting resistors? Its speed varies widely between full-load and no-load. In fact, most DC generators can be made to act as DC motors, and vice versa. Increasing shunt-field circuit resistance increases motor speed. This EMF opposes the applied inteerpole, and limits the flow of armature current.


The DC motor is reversed by reversing the direction of the current in the armature. The automatic devices are usually just switches controlled by motor speed sensors. The field strength varies with changes in armature current.

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. This causes the neutral wkndings to be shifted in the direction opposite to that of armature rotation. Excessive current will flow interpkle DC voltage is first applied unless current is limited in some way.

Pages through See the editorial for more information Its starting torque is greater than other types of DC motors. The inductance of the coil tends to retard the reversal of the coil current by generating a prolonging voltage.


In a generator the interpoles must be of the same polarity as the main poles which they precede in the direction of rotation.

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 interpoke circuit design engineer. It maintains a constant speed under varying loads.