Commutation is indeed the process of switching the field in the armature windings to make constant torque in one direction with the purpose of ensuring that the torque acting on the armature is always in the same direction and the device connected to the armature enabling this current switch is the commutator.
What is purpose of commutation?
The basic purpose of commutation is to ensure that the torque acting on the armature is always in the same direction. The voltage generated in the armature is alternating in nature, and the commutator converts it to direct current.
What is motor commutation?
A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. … By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced.
What is the effect of commutation?
Effects of Commutation. The computation is called Ideal commutation when the reversal of current is completed by the end of the commutation period. If the current reversal is completed during the commutation period, sparking occurs at the contact of brushes and overheating occurs damaging the surface of the commutator.
What do you mean by commutation explain?
1 : exchange, trade. 2 : replacement specifically : a substitution of one form of payment or charge for another a commutation by money payment for the exacted service. 3 : a change of a legal penalty or punishment to a lesser one commutation of a death sentence.
What causes poor commutation?
Causes of Poor Commutation
Poor mechanical conditions like uneven surface of commutators, vibrations of brushes etc. 2. Poor electrical conditions such as increased voltage between the bars of commutators, increase in the current density of brushes etc. Practically Ideal Commutation is not possible.
What are the types of commutation?
Three types of commutation are identified: i) Voltage commutation, ii) Current commutation and iii) Load commutation. In a voltage commutated thyristor circuit a voltage source is impressed across the SCR to be turned off, mostly by an auxiliary SCR.
How can I improve my commutation?
There are three main methods of Improving commutation or obtaining sparkles Commutation. These are Resistance Commutation and Voltage Commutation and Compensating Winding.
- Resistance Commutation.
- Voltage Commutation.
- Brush Shift.
- Commutating Poles or Interpoles.
- Compensating Windings.
What is ideal commutation?
(also called straight-line commutation) is that in which the current of the commutating coils changes linearly from + to in the commutation period as shown in Fig. 7.15. The figure also shows delayed commutation and the current in the spark.
What kind of motors use commutation?
While brushless motors come in single-phase and two-phase variations, three-phase motors are by far most common. One simple way to control brushless motors is with trapezoidal commutation.
What is commutation system and time?
Commutation in DC Machine or Commutation in DC Generator or Motor. … It is called commutation period. After this short-circuit time the armature coils rotates under S pole and rotates between a negative brush and its succeeding positive brush.
What is delayed commutation?
The time of the short circuit is called the period of commutation. … Thus, the cause of sparking at the commutator is the failure of the current in the short-circuited elements to reach the full value in the reverse direction by the end of the short circuit. This is known as under commutation or delayed commutation.
How do you calculate commutation time?
Time of short circuit = Tc = (time required by commutator to move a distance equal to the circumferential thickness of brush)–(one mica insulating strip). If brush width is given in terms of commutator segments, then commutator velocity should be converted in terms of commutator segments/seconds.
What is a commutation payment?
A commutation is where you (the worker) and insurer agree to a single lump sum payment. This payment removes the insurer’s liability to pay future weekly payments and/or medical, hospital and rehabilitation expenses for the injury.
What is the definition of commuted?
1a : change, alter. b : to give in exchange for another : exchange commuting foreign currency to domestic. 2 : to convert (something, such as a payment) into another form The periodic payments may be commuted into a lump sum.
What commuted means in law?
Commutation, in law, shortening of a term of punishment or lowering of the level of punishment. For example, a 10-year jail sentence may be commuted to 5 years, or a sentence of death may be commuted to life in prison.