How does armature reaction affect commutation?
The armature reaction causes shifting the magnetic neutral axis. Therefore there will be some flux density at brush axis which produces emf in the coil undergoing commutation. This will lead to delayed commutation. Thus the armature reaction at brush axis must be neutralized.
What is the formula for armature current?
Armature Current for DC shunt generator calculator uses Armature Current = Field Current+Load Current to calculate the Armature Current, Armature Current for DC shunt generator is the Current which Flows in Armature Winding or rotating Winding of Motor or generator.
What is armature commutation?
Commutation is the process of switching the field in the armature windings to produce constant torque in one direction, and the commutator is a device connected to the armature, which enables this switching of current. The lever arm for the torque produced on the armature varies with the angle of the coil (cos α).
What do you mean by armature reaction and commutation how these can be improved?
The armature reaction creates a flux in the neutral zone and due to this flux, a small voltage is induced in the commutating coil. Therefore, by shifting the brushes to the new MNA, the sparkless commutation can be obtained.
What is armature reaction in a dc machine How does it affect commutation what steps are taken to have effective commutation?
The current flowing through the armature conductors creates a magnetic field, which is called as armature flux. This armature flux distorts and weakens the magnetic flux produced by the main poles. This effect of armature flux on the main flux is known as armature reaction.
What is commutation in DC machines?
The commutation in DC machine or more specifically commutation in DC generator is the process in which generated alternating current in the armature winding of a dc machine is converted into direct current after going through the commutator and the stationary brushes.
How do you calculate armature winding?
Pole Pitch is equal to the total number of armature slots divided by the total number of poles in the machine. For example, if there are 96 slots on the armature periphery and 4 poles, the number of armature slots that come between two adjacent pole centers would be 96/4 = 24.
How do you calculate armature resistance?
To calculate the armature resistance, subtract the back e.m.f from the voltage, then divide by the armature current.
Is commutator and armature the same?
An armature is a combination of the winding, commutator, brushes, and ball bearings….What is Commutator?
|It receives current from the armature windings
|It receives current from the armature core
|The core consists of armature windings, commutator, and brushes
|It has some segments
How do you improve commutation?
Methods of Improving Commutation
- Resistance Commutation.
- Voltage Commutation.
- Brush Shift.
- Commutating Poles or Interpoles.
- Compensating Windings.
How do you calculate back EMF of a dc motor?
Back EMF = -45 V. Net voltage across the motor, calculated according to Ohm’s Law (V = I x R = 10 A x 15 Ω), = 150 V.
How is commutation done in DC motor?
What is GNA and MNA in armature reaction?
What are GNA and MNA? The geometrical neutral axis is always perpendicular to the stator field axis or main flux axis whereas MNA means magnetic neutral axis the axis where no electromotive force induces in the armature conductor. The brushes are placed in that axis where no emf induces, so brushes are safe.
What is commutation in DC generator?
What is Z SA calculation during design of armatures?
What is ‘Z/Sa’ calculation during design of armatures? Explanation: This is the second step in the armature design. Firstly, the number of armature conductors is found out. Then the number of slots used is taken and the ratio of both gives the value of ‘Z/Sa’.
How to calculate armature current?
To calculate Armature Current, you need Field Current (If) and Load current (Il). With our tool, you need to enter the respective value for Field Current and Load current and hit the calculate button. You can also select the units (if any) for Input (s) and the Output as well.
What is armature reaction?
The action of armature flux on the main flux is called armature reaction. In the previous chapter (Sec 1.19), it was hinted that current in the coil is reversed as the coil passes a brush. This phenomenon is termed as commutation.
How to neutralize the reactance voltage of armature reactions?
Since the interpoles carry the armature current and the reactance voltage is also proportional to armature current, the neutralization of reactance voltage is automatic. (ii) The m.m.f. of the compoles neutralizes the cross-magnetizing effect of armature reaction in small region in the space between the main poles.
What is resistance commutation?
This method of improving commutation is called resistance commutation. Figs. (2.11) and (2.12) illustrates how high contact resistance of carbon brush improves commutation (i.e., reversal of current) in coil A.