2017 - 07 - 28
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Basic conceptsa. EMC, EMI and EMSElectromagnetic Compatibility (EMC) means the compatibility of products that are in the same electromagnetic environment (electric field and magnetic field). It has 2 ...
2017 - 07 - 28
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Magnetic circuitThis article tries to introduce PMDC motor’s magnetic circuit by the most acquainted concepts. It also tries to introduce some characteristics and parameters of the motors by means of ...
2017 - 07 - 28
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Basic conceptsMotor is an energy conversion device that converts electric energy into mechanical energy or mechanical energy into electric energy, using magnetic field as media.PMDC motor is an energy...
Evaluation of motor

 Evaluation of motor
How to evaluate a motor? Typically industrial products can be evaluated with the following aspects. The most
important characteristic of industrial products is low deviation. 
(1) Full dimensions
The fundamental characteristics that customers require are assembling dimensions and outline dimensions. The
dimensional deviation of a good product should meet product standard requirement. (GB standard, industrial
standard or enterprise standard)
(2) Basic performance
a. Rated voltage: known parameter (unit: V) b. No load current: I0 (unit: A)  c. No load speed: n0 (unit: rpm)
d. Rated current: IL (unit: A)               e. Rated torque: TL (Unit: f. Rated speed: NL (Unit: rpm)
g. Current in stall: Ist (unit: A)             h. Torque in stall: Tst (unit:
i. Other parameters such as efficiency, power, electric potential constant, torque constant etc. can be calculated
from the above data. 
(3) Special characteristics
a. Vibration: amplitude (unit: mm), vibration velocity (unit: mm/s), vibration acceleration (unit: mm/s2)
b. Noise: sound pressure LP (unit: dB(A) and acoustical power LW (unit: dB(A). They are both relative values. 
c. EMC: This index is to evaluate the ability of the motor resisting the radio interference or the radio interference
level that the motor generates.
d. Environment test: This is to judge the load capability of the motor under high and low temperature. Alternating
temperature test is the common test. Alternating temperature and humidity test is more severe test. Magnetic field
of ferrite magnet decreases by 5-7% under -80 ℃. The motor electric performance is therefore deviated.
Mechanical shock, external alternating magnetic field, aging (long time) storage will also weaken the magnetic
e. Others: such as safety clearance, safety creepage distance, protection class, type of cooling etc.

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