Simply put, DC motors can turn in either direction (clockwise or counter-clockwise) and can be easily controlled by inverting the polarity of the applied voltage. If a motor is already in motion, the applied voltage can be inverted and the motor will decelerate quickly, eventually stopping. …
How do you change the direction of a DC motor?
DC motors, like AC motors, can be configured to turn in either direction. Their direction can be easily controlled by inverting the polarity of the applied armature voltage by reversing the armature leads. This works with shunt, series, and compound wound DC motors.
What happens if you turn a DC motor backwards?
If you try to stop or reverse it manually, then it will try to draw whatever current is needed to continue running at that speed. The high current could heat the motor to the point of damage, unless the power supply limits the current.
How can DC motors be reversed without changing the type of compounding?
The motor is reversed by reversing current flow through the armature, but keeping the shunt field current in the same direction. … A field discharge resistor is also used to pre vent the sudden collapse of the shunt field flux as it’s disconnected from the line power. ill.
Why starters are required in a DC motor?
Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.
How much voltage drop does it take to cause problems to a motor?
In general, satisfactory motor performance requires a voltage within ± 5% of its rated nominal value in steady-state operation, Starting current of a motor can be 5 to 7 times its full-load value (or even higher). If an 8% voltage drop occurs at full-load current, then a drop of 40% or more will occur during start-up.
Can you reverse an electric motor?
Motor rotation is essentially created by the manipulation of wires and magnetic fields. Thus, you can often reverse AC motors by switching the wire connections. This is as easy as unhooking and re-crimping the designated wires.
Which DC motor is preferred for constant speed?
Que 28. Which D.C motor is preferred for machine tools? Explanation: DC shunt motor is a constant speed motor tool machine such as lathe machine requires being run at a constant speed.
What is back emf in dc motor?
When the armature of the DC motor rotates under the influence of driving torque, the armature of the conductors moves through a magnetic field inducing an emf in them. The induced emf is in the opposite direction to the applied voltage and is known as the back emf.
Can we change the direction of rotation of DC shunt motor?
The direction of rotation of DC shunt motor can be reversed by reversing either field terminals or armature terminals but not both. … Hence the motor will rotate in the same direction by changing the supply connections.