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Introduction to Electric motors
  1. [ 2012/12/20 ]

Table of content

1. Naming convention
2. Basic Characteristics
3. Advanced Characteristics

Naming convention

The general format of naming is:  aabbccMdd

It consists of four parts, each part has two characters:
1. “aa” indicate the type of motor, HC means universal motor, DC means dc motor, SP means shaded pole motor, VB means vacuum motor, IN means induction motor.
2. “bb” indicate the outer diameter of stator, which is measured in mm and it’s straight forward.
3. “cc” indicate the thickness of stator, , which is measured in mm and it’s straight forward.
4. “dd” indicate the rated voltage of the motor. 

For example: DC4843M23. The type of the motor is DC. The outer diameter of stator is 48mm. 43 means that the thickness of the stator is 43mm. The voltage of the motor is 230v.   

Basic Characteristics

The very basic aspects of the motor(or any electrical device) is voltage, current and power.

1. Voltage is a physical quantity that measures the energy difference which generated by the unit charge in the electrostatic field because of the different potential.  The magnitude of voltage equals to the work made by the unit positive charge moved from one point to another point due to the action of electric field force. 

Voltage is measured in Volts (U). And voltage can be measured by the voltmeter. Connect it in parallel with a circuit to be tested.

2. Current refers to the directional movement of charge. When closing a circuit with a power supplied, the current produces. 

The unit of current is Ampere (I) which is used to memorize the French physicist Ampere. The current is measured by amm ammeter.

3. Power refers to the work made by the object in per time. It is a physical quantity describing the work speed. The greater the power, the higher the speed. 

Watt (P) is the unit of power. Power can be measured by the watt meter.  There is a certain relationship between the three. That is P=UI.

Advanced Characteristics

1. Speed, namely rpm speed. RPM generally stands for Revolutions per minute, and is a measure of the frequency of a rotation. It interprets the number of full rotations completed per minute around the shaft.  Speed is one of the output parameter of the motor, the other parameter is torque.

2. Torque is formally defined as “ The quantitative measure of the tendency of a force to cause or change rotational motion is called torque”.  For the type of motor that manufactured by CJC, the torque ranges from 10 m.Nm to 3,000 m.Nm. 100 m.Nm equals to 1  A intuitive understanding of 100 m.Nm is that 100 m.Nm is the torque of a stand mixer for mixing 1.6 liter fruit.

3. Efficiency is the parameter of the percentage of power that is actually put into work. Efficieny = Output power / Input power. As there’s always iron lose, motor component heating lose, etc. The input power of the motor could never be purely transformed into output power. A universal motor ‘s efficiency is generally 45% or less. A dc motor could have the efficiency of more than 70%. The gap of efficiency for different motors origin from its structure.

4. Noisy measures the sound level when the motor spins. It’s measured in dB.

5. Life time measures how long the motor could run, which is based on the motor ‘s working duty. For example, a typical description of the motor is “105hrs S3 33% (2min on, 4 min off)”.

Different type of motor varies on the pattern of the characteristics, For example, the speed of the universal motor is high and the range is wide. It has a large starting torque and strong capability . But an obvious drawback is that the noise level is a little bit high.