What affected the speed of rotation of the armature?
The speed of rotation of such a motor can be changed by changing the size of the current to the armature coil. D.c. motors with field coils are classified as series, shunt, compound and separately excited according to how the field windings and armature windings are connected.
How does resistance affect the speed of a motor?
As we increase the armature Resistance, the drop across armature increases, which cause in decrease in the speed. As we add external Resistance in Rotor, the field current will decrease which causes decrease in Flux per pole (phi) , hence speed of the motor increases.
How does the number of coils affect the speed of an electric motor?
More windings requires more poles and speed decreases with more number of poles. Increasing the number of turns increases the length of conductor which in turn increases the magnetic field induced.
What happens to current flow and torque in a motor that is stalled?
Stalling is a condition when the motor stops rotating. This condition occurs when the load torque is greater than the motor shaft torque i.e. break down torque condition. In this condition the motor draws maximum current but the motor does not rotate. This current is called as Stalling current.
What causes the armature to rotate in a simple motor?
What causes the armature to rotate in a simple motor? (In a simple motor, a current is supplied to the armature and with this current is a magnetic field. This created magnetic field causes the armature to rotate as it tries to align with the external magnetic field.)
What is armature circuit?
DC Armature. The armature of an electric machine is the name historically given to the winding where a voltage is induced and power transfer between electrical and mechanical systems occurs. It is a term used in dc machines and ac synchronous machines. In a dc machine, the armature is the rotating circuit.
How do you slow the speed of a motor?
A couple of things you can do:
- Use gears to change ratio of speed, which is what you’re going to do.
- Use a stepper motor, which are commonly used for high-torque, low RPM applications.
- Find some sort of PWM control circuit to slow it down, although you probably won’t be able to get it down to 5-10RPM.
How can the resistance of a motor be increased?
The only change in motor resistance would be an increase from IR heating of the wire. The only change in inductance would be if the voltage gets high enough to saturate the magnetics, which would cause a reduction in the inductance.
What affects the speed of an electric motor?
DC controls adjust speed by varying the voltage sent to the motor (this differs from AC motor controls which adjust the line frequency to the motor). Typical no load or synchronous speeds for an AC fractional horsepower motor are 1800 or 3600 rpm, and 1000-5000 rpm for DC fractional hp motors.
Why does a coil rotate when there is a current in the coil?
The coil of wire is mounted in the gap between the two magnets. The split rings make electrical contact with the coil and reverse the current every half turn. When an electric current flows through the coil, a force is exerted on the coil, causing it to spin.
Why do motors stall?
Stalling is a condition when the motor stops rotating. This condition occurs when the load torque is greater than the motor shaft torque i.e. break down torque condition. In this condition the motor draws maximum current but the motor do not rotate. The current is called as Stalling current.
What causes a motor to stall?
It is commonly applied to the phenomenon whereby an engine abruptly ceases operating and stops turning. It might be due to not getting enough air, energy, fuel, or electric spark, fuel starvation, a mechanical failure, or in response to a sudden increase in engine load.
What causes an armature coil to rotate in a magnet?
When a current flows through the armature coil, forces act on it as a result of its current carrying conductors being in the magnetic field provided by the permanent magnet and so cause the armature coil to rotate.
What is the direction of current induced by a magnetic rod?
The direction of the current induced by the rod’s downward motion is counterclockwise, since this direction produces a magnetic field within the loop that points out of the page—in the same direction as the original field.
How to control the speed of a permanent magnet motor?
The speed of a permanent magnet motor can be controlled by varying the current through the armature coil, with a field coil motor by either varying the armature current or the field current though generally it is the armature current that is varied. Thus speed control can be obtained by controlling the voltage applied to the armature.
What affects the speed of a DC motor?
DC Motor Speeds. The number of wire turns in an armature, the operating voltage of the motor, and the strength of the magnets all affect motor speed. If a DC motor is running on a 12 V battery, that is the maximum voltage available to the unit and the motor will only be able to perform at a speed rated for 12 V.