Contents
How many poles are there in DC motor?
Realistic designs for dc machines usually have more than 2 poles. Increasing the number of poles for a particular flux per pole will increase the induced voltage at a given speed and increase the torque available per amp. Fig. 1 gives an illustration of the layout of a stator with 4 poles.
How do you find the number of poles in a DC motor?
When selecting a three phase motor, the number of poles is chosen to achieve the speed of rotation that you require. Here are two tables, one for a 50 Hz power supply and one for a 60 Hz power supply: The formula is n = 60 x f /p where n = synchronous speed; f = supply frequency & p = pairs of poles per phase.
What is the minimum number of poles a brushed DC motor has and why?
This leads to a short circuit of the inputs, condition that can damage the power supply and reduce efficiency. For this reason, most small electromechanical DC motors have a minimum of three poles.
What are the criteria for selecting a motor for particular operation?
10 things to consider when choosing an electric motor
- Vehicle characteristics.
- Driving cycles.
- Vehicle configuration (electric, hybrid)
- Maximal speed.
- Maximal torque.
- Maximal power.
- Battery Capacity.
- Battery Voltage.
Why are motors with different number of Poles?
If you are using 50Hz and have a two pole motor 60 x 50 / 1 = 3000 rpm. The induction motor will run at a slight less speed due to “slip” which is what gives the motor its torque.
How is the power supply of a DC motor represented?
The external power or power supply, E, is connected to the brushes through the armature. The armature is represented by its equivalent resistance, Ra. The current through the armature is Ia. The mechanical terminal (output) contains the shaft connected to the motor and the armature.
How does a DC motor maintain the same speed under variable load?
An important feature of DC motors is their ability to maintain the same speed under variable load. To see how this is possible, let’s assume that the motor is running at a speed of ω with a back e.m.f. of Eb. If the load is, for instance, increased, the speed will be reduced and Eb will decrease.
What is the armature resistance of a DC motor?
A DC motor is connected to a source of 150 V, and its armature resistance is 0.75 Ohms. The armature generates 40 V when running at a speed of 400 rpm.