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What happens to the speed of motor while the excitation current is decreasing?
Wiki User
∙ 11y ago
Assuming there is no mechanical load, as the speed approaches the synchronous speed the slip decreases and the current induced in the rotor also decreases. The stator coil begins to approximate a pure inductor and that causes the current to fall. In the steady state the power drawn is used to overcome friction in the bearings and windage only.
Wiki User
∙ 8y ago
Wiki User
∙ 14y agoWhat you are talking about here is back EMF (Electro Motive Force).
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Does the value of the exciting current of your 3-phase motor depend on the rotor speed?
An induction motor has no excitation, so the question is about a synchronous motor. The rotor speed is determined by the supply frequency. For a given supply frequency and mechanical load, the excitation current can be adjusted to give the best power factor.
Which excitation synchronous motor drawn reactive power?
Hi, Under excitation - inductive reactive power Over excitation - Capacitive reactive power.
What is the electrical term excitation mean?
Excitation is normally used to describe the current supplied to the field winding of a motor. A motor has a rotating armature with a coil that rotates in the magnetic field produced by a fixed field coil. The current in the field coil can be taken from a series or parallel connection to the armature coil, or (usually for larger motors) it can be supplied independently via some sort of controller. Excitation can be used to control the speed of DC motors or the power factor of synchronous motors.
How do you cut off the excitation of a dc motor?
short leads
Does a induction motor need excitation?
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 synchronous motor theory is excitation current the same as field current?
yes. excitation current is same as field current to my knowledge
Does the value of the exciting current of your 3-phase motor depend on the rotor speed?
An induction motor has no excitation, so the question is about a synchronous motor. The rotor speed is determined by the supply frequency. For a given supply frequency and mechanical load, the excitation current can be adjusted to give the best power factor.
If you increase or decrease the frequency what effect on electrical machin?
If you're talking about an electric motor, increasing the frequency will increase the speed of rotation of the motor, and decreasing the frequency will decrease the speed of rotation of the motor. The other way of controlling a motor is to control the current; increasing the current increases speed, decreasing current decreases speed.
Why would a dc motor show high amps no voltage and struggle to turn?
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.
Is reluctance motor is a synchronous motor with dc excitation?
yes
What is excitation of a DC motor?
DC Voltage
Which excitation synchronous motor drawn reactive power?
Hi, Under excitation - inductive reactive power Over excitation - Capacitive reactive power.
What is the electrical term excitation mean?
Excitation is normally used to describe the current supplied to the field winding of a motor. A motor has a rotating armature with a coil that rotates in the magnetic field produced by a fixed field coil. The current in the field coil can be taken from a series or parallel connection to the armature coil, or (usually for larger motors) it can be supplied independently via some sort of controller. Excitation can be used to control the speed of DC motors or the power factor of synchronous motors.
How do you cut off the excitation of a dc motor?
short leads
Does a induction motor need excitation?
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.
What happens if a DC motor is made to rotate?
may be current is produced
Give 5 types excitation of DC motor?
there are 2 different types f excitation 1 seperately excited 2 self excited
