When the field current is increased, the field flux is increased. More counter EMF is developed, which opposes the armature current. The armature current then decreases, and the motor slows down. When the voltage applied to the armature is decreased, the armature current is decreased, and the motor again slows down.
What happens if you increase the current in a motor?
An increase in current is a danger to the motor only if that current exceeds the motor’s nameplate current rating. When amps go above the nameplate rating, heat begins to build up in the motor. Without a timely correction, this heat will damage the motor.
What would happen to the rotation of the motor if the direction of the current was reversed?
When the current is reversed the rotational direction of the motor is also reversed. … Now,when we change both the electric current and magnetic field simultaneously, the direction of the rotation of the motor stays the same. Because the reversion of the direction by each of the elements are cancelled by each other.
What increases the speed of a motor rotation?
The speed of rotation of an electric motor can be varied based on the following factors: Magnetic flux – By decreasing the flux, the speed of the motor can be increased. The flux can be changed by changing the current with a shunt field rheostat. … This increased torque causes the dc motor to increase in speed.
What are the 3 ways to increase the speed at which the electric motor changes?
increasing the size of the current; using a stronger magnet; increasing the number of turns of wire in the coil; reducing friction between the coil and the axel it rotates on.
What causes a motor to draw more current?
Electrical overload or over-current is caused by an excessive current flow within the motor windings, exceeding the design current which the motor is able to carry efficiently and safely. This can be caused by a low supply voltage, resulting in the motor drawing in more current in an attempt to maintain its torque.16 мая 2018 г.
Does current affect motor speed?
The speed of a motor is determined by the voltage and the torque by the current. If a motor is running at a certain speed with a constant torque and the load increases, the current will increase and so also the torque to maintain the same speed.8 мая 2014 г.
In what ways can a motor be made more powerful?
Motor can be made more powerful by winding the coil on a soft iron core of by increasing the number of turns of the coil. (iii) both current and magnetic field were reversed simultaneously.
What happens to the direction of rotation of a motor if both current and magnetic field were reversed simultaneously?
The direction of rotation of the motor will not change if both current and magnetic field are reversed simultaneously.
Which rule gives the direction of induced current?
Fleming’s Right hand rule
How do you make an electric motor spin faster?
ANSWER: In order to make the motor spin faster or slower you must increase or decrease the strength of the magnetic field. This is done by either changing the amount of current running through the motor or varying the distance of the permanent magnets from the motor.
What determines electric motor speed?
The speed of an electric motor is determined by its physical construction and the frequency of the voltage supply. Electrical engineers select motor speed based on the needs of each application, similar to how horsepower is specified based on the mechanical load.
What is the speed of a 4 pole motor?
around 1800 rpm
How do you change the speed of a motor?
AC motors are constant speed devices but their speed can vary if you change the input voltage or frequency or the windings that make the motor rotate. The most common and efficient way of changing the speed is to vary the frequency by using an inverter as the power supply.
How can we increase the speed of synchronous motor?
Changing the number of poles is not easy, so we do not use that method. However, with the invention of solid-state devices, the frequency of the current fed to the synchronous motor can be varied. We can control the speed of the synchronous motor by changing the frequency of the supply to the motor.
How do you increase the speed of a DC motor?
Thus, the speed of a DC motor can be controlled in three ways:
- By varying the supply voltage.
- By varying the flux, and by varying the current through the field winding.
- By varying the armature voltage, and by varying the armature resistance.