Why equalizer ring is not used in wave winding?

Why equalizer ring is not used in wave winding?

Equalizer Ring: As in lap winding number of parallel path is more, there would be severe sparking at brushes due to difference in currents in different parallel paths. But in wave winding number of parallel paths is 2 and the sparking at commutation is less.

Why Equalising connections are used in lap winding?

In lap winding all the conductors in any parallel path lie under one pair of poles. If flux from all the poles is exactly the same, the induced emf in each path hence current carried by each path will be equal.

What is the difference between lap and wave winding?

The main difference between these two is, in the lap winding, One of the major difference between them is that in a lap winding, the last part of every coil is associated with the nearby sector while in the wave winding the last part of armature coil is associated with the commutator sector at a distance apart.

Which winding is used for High Voltage?

4.6

Lap Winding Wave Winding
The emf of lap winding is less The emf of wave winding is more.
The efficiency of the lap winding is less The efficiency of the wave winding is high.
The lap winding is used for high current, low voltage machines The applications of wave winding include low current and high voltage machines.

What is the purpose of equalizer rings?

Hence, the function of equalizer rings is to avoid unequal current distribution at the brushes and to reduce sparking between brushes and commutator. The equalizer rings are low resistance copper conductor which connects those points in the armature winding which have potential difference between them.

What is equalizer connection?

To relieve the brushes of these circulating currents, points on the armature that are at the same potential are connected together by means of copper bars called equalizer rings. This is achieved by connecting to the same equalizer ring the coils that occupy the same positions relative to the poles.

What is the EMF equation of DC generator?

As the armature rotates, a voltage is generated in its coils. In the case of a generator, the emf of rotation is called the Generated emf or Armature emf and is denoted as Er = Eg. In the case of a motor, the emf of rotation is known as Back emf or Counter emf and represented as Er = Eb.

What is difference between coil and winding?

Coil: A coil is formed by connecting several turns in the series. Winding: A winding is formed by connecting several coils in series.

Why wave winding is used for high voltage?

The conductors in each of the two parallel paths distributed around the armature in the entire circumference. For a given number of poles and armature conductors, it gives more emf than that of lap winding. Hence wave winding is used in high voltage and low current machines.

What is dummy coil?

The dummy coils are similar to other coils except their ends are cut, short and taped. They do not connect with the commutator bars. The dummy coils are simply to provide mechanical balance for the armature. As they do not connect with commutator bars, they do not affect the electrical characteristics of the winding.

What are Interpoles used for?

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”.

Why back EMF is used in DC motor?

When the armature of the DC motor rotates under the influence of driving torque, the armature of the conductors moves through a magnetic field inducing an emf in them. The induced emf is in the opposite direction to the applied voltage and is known as the back emf.

How are dummy coils used in a circuit?

Some slots are kept without armature winding in that case and dummy coil or coils are employed in that slots. The dummy coils are similar to other coils except their ends are cut, short and taped. They do not connect with the commutator bars. The dummy coils are simply to provide mechanical balance for the armature.

Can a wave winding be used with more than one coil?

The wave winding is possible only with particular number of conductor or coils. But sometimes the armature slots available in the armature winding do not meet the requirement of the winding. ( It means that the available number of slots is more than the required number of conductors ).

Can a wave winding be used in an armature winding?

The wave winding is possible only with particular number of conductors but sometimes the standards armature punchings available in armature winding shops do not meet with the requirements of the winding as these may accommodate more than the required number of conductors. In such cases dummy coil or coils are employed.

What does it mean when a coil is inactive?

Let us consider that the wave winding of 26 slots and 4 – poles. But the YA must be an integer therefore the winding is not possible with 52 conductors. However if the number of coils are 25 It means that one coil ( 26 – 25 = 1) is inactive, it is called as dummy coil.