What factors increased the speed of DC motor?
The speed of rotation of the coil in a D.C. motor can be increased by: (i) Increasing the strength of the current, (ii) Having more turns in the coil, (iii) Increasing the area of the coil, (iv) By increasing the strength of the magnetic field.
What determines the speed of a DC 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.
Can you overspeed a DC motor?
Because the speed of DC motor is inversely proportional to the magnetic field, once the magnetic field is less than the minimum allowable value. The speed of the motor will exceed the maximum allowable value. Therefore, an overspeed switch is installed on the axis of the DC motor.
What speed will the motor rotate?
Motor Wiring and Number of Poles
A 60 Hz power supply changes polarity 60 times per second, and a two-pole motor will spin at 3,600 rpm when connected to this source. A four-pole motor will only rotate at 1,800 rpm. For 50 Hz motors, the speed is 3,000 rpm with 2 poles, and 1,500 rpm with 4 poles.
What is the maximum rpm of DC motor?
Speed @ maximum efficiency: 8600 RPM.
What is the maximum speed of DC motor?
The nominal maximum speed and power are 24000 RPM and 0.815 HP. In particular, these machines must operate loaded in order to avoid damage.
What causes electric motor overspeed?
What happens to cause a motor overspeed fault on an AC drive? A few causes may be that the acceleration time is set too fast and causes the motor to overshoot the target speed. A sudden change in the load may also cause the drive to indicate an over speed condition.
Why does a DC motor draws high current at starting?
Answer: The starting current is high as there is no back EMF or counter EMF present in the armature circuit because atstarting counter EMF is zero. … It’s armature has very less resistance due to this it need more current at starting time. Hence DC starters are used to limit the starting current ofmotor.
Which of the following will develop the maximum power by a DC motor?
The maximum power is developed in the motor when the back emf is equal to half of the supply voltage. Back EMF in DC Motor: When the current-carrying conductor placed in a magnetic field, the torque induces on the conductor, the torque rotates the conductor which cuts the flux of the magnetic field.