Table of Contents
- 1 What is the main purpose of Interpoles?
- 2 Under what circumstances do compensating windings need to be provided to reduce the effects of armature reaction in DC machines?
- 3 What causes commutation in dc machines?
- 4 What is the use of interpoles in DC machines?
- 5 How do interpoles cancel out armature reaction?
What is the main purpose of Interpoles?
Interpoles – Are coils that are placed between the field coils that generate a field that is used to prevent excessive sparking of the brushes. Interpoles, also known as compensation windings, are extra field poles “in-between” the main field poles, thus “interpoles”.
How are Interpoles connected in DC generators?
Inter-poles are similar to the main field poles and located on the yoke between the main field poles. The inter-pole winding is connected in series with the armature winding because the inter-pole must produce flux that is directly proportional to the armature current.
Under what circumstances do compensating windings need to be provided to reduce the effects of armature reaction in DC machines?
The main purpose of compensating winding is to nullify the effect of armature reaction on the main field flux under the pole faces in DC machine. Due to the effect of armature reaction mmf, the flux distribution under the pole faces is distorted which leads to poor commutation and flashover.
What is the purpose of compensating winding in DC generator Mcq?
Compensating winding are used in DC machines to neutralize the cross magnetizing effect of armature reaction. Cross magnetizing effect changes with load current and it results in shifting of the magnetic neutral axis.
What causes commutation in dc machines?
The currents induced in the armature conductors of a DC generator are alternating in nature. The change from a generated alternating current to the direct current applied involves the process of Commutation.
What is meant by commutation in DC machines describe the process of commutation in DC machines through the reversal of current in a coil?
Commutation in DC machines is the process by which the reversal of current takes place. In DC generator this process is used to convert the induced AC in the conductors to a DC output. In DC motors commutation is used to reverse the directions of DC current before being applied to the coils of the motor.
What is the use of interpoles in DC machines?
Interpoles are used in DC Machines to reduce the effect of armature reaction and self induction, mainly in winding at commutators,of DC motors. Interpoles are connected in series with armature winding so that as the armature current changes the flux due to interpoles chances accordingly.
What is the main purpose of interpole winding?
Main purpose of interpoles is to improve commutation by reducing the armature reaction. interpole winding is connected in series with armature winding through brushes to neutralize the armature flux in the interpolar region.
How do interpoles cancel out armature reaction?
The field generated by the interpoles produces the same effect as the compensating winding. This field, in effect, cancels the armature reaction for all values of load current by causing a shift in the neutral plane opposite to the shift caused by armature reaction.
How does the polarity of an interpole motor depend on the armature?
Any changes in the armature current due to armature reactance, loading, or self-inductance pass through the interpole windings. This creates a changing magnetic field equal to and opposite that of the armature, thereby cancelling the effect. For DC motor Polarity of an interpole depends on the direction of rotation.
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