short leads
there are 2 different types f excitation 1 seperately excited 2 self excited
on the basis of field excitation, dc generators are classified into the following types:-1- separetly excited dc generators2-self excited dc generatorsthe behaviour of a dc generator on load depends upon the method of field excitation adopted
The induction motor is the special kind of motor which runs below and above the synchronous speed. which the synchronous motor runs nearly equal the synchronous speed. The operation of synchronous motor runs with dc field excited hence separate dc field current is given to the field circuit. where as the induction motor the field and main field is drawn from the same supply hence no excitation is required. But due to this separate starting mechanism has to be required in case of the single phase induction motor.
In general terms, 'excitation' simply describes the process by which an electric current produces a magnetic field. But, more specifically, it refers to the creation of the magnetic field by the field windings of a motor or generator. In the case of an alternator, for example, the armature windings (the windings into which voltages are induced) are stationary, and inserted into slots cut into the inner face of the stator. The field is then provided by the rotor which is supplied (via slip rings) with a 'excitation' current provided by an external d.c. voltage.
No
DC Voltage
yes
To start an induction motor we have to excite field. The excitation is done by connecting the DC supply to the field winding's.
there are 2 different types f excitation 1 seperately excited 2 self excited
on the basis of field excitation, dc generators are classified into the following types:-1- separetly excited dc generators2-self excited dc generatorsthe behaviour of a dc generator on load depends upon the method of field excitation adopted
The induction motor is the special kind of motor which runs below and above the synchronous speed. which the synchronous motor runs nearly equal the synchronous speed. The operation of synchronous motor runs with dc field excited hence separate dc field current is given to the field circuit. where as the induction motor the field and main field is drawn from the same supply hence no excitation is required. But due to this separate starting mechanism has to be required in case of the single phase induction motor.
In general terms, 'excitation' simply describes the process by which an electric current produces a magnetic field. But, more specifically, it refers to the creation of the magnetic field by the field windings of a motor or generator. In the case of an alternator, for example, the armature windings (the windings into which voltages are induced) are stationary, and inserted into slots cut into the inner face of the stator. The field is then provided by the rotor which is supplied (via slip rings) with a 'excitation' current provided by an external d.c. voltage.
The current flowing in a dc motor is determined by (Applied voltage-Motor EMF) divided by armature resistance. The motor emf is a function of the field excitation of the motor and the speed at which the motor turns. When the motor starts, there can be no EMF because motor speed is 0 rpm. Therefore the motor will draw more current. But as the motor begins to speed up, if it has field excitation, it has to build up EMF and the current will drop. So : If the motor shows high amps and no voltage and struggles to turn the possible reasons are: 1. The motor has no excitation - The permanent magnets are weak or the field winding is faulty or the field is not being supplied. 2. The armature winding is faulty - it has shorted windings. This assumes your supply is healthy of course.
No
excitation voltage is sinusoidal because it is taken from the terminal of alternator but excitation current is non-sinusoidal because it always dc.
Take the back off and look inside.
If the synchronous motor is running near synchronous speed, it will begin rotating at synchronous speed when DC is applied to the rotor. Source: Electrical Machines, Drives, and Power Systems Theodore Wildi Section 17.3