How to determine the efficiency of the motor by the B method (input and output loss analysis)
The B method is called the “input and output loss analysis method”, and an efficiency test method is required when the motor is energy-saving certified (mainly for the product energy efficiency limit control requirements, and the GB18613 standard stipulates that it is performed according to the requirements). Ms. Participate in today's B-test to make an exchange with everyone.
Instructions for the B method test
When using the B method to obtain efficiency, direct load test and no-load test at rated voltage and rated frequency are required to obtain several sets of input current, input power, output power (or torque), rotational speed, and core loss and mechanical loss values. Then, the relevant test values are corrected, and the corrected input power and output power are obtained. Finally, the efficiency of each test point is obtained by comparing the output power with the input power, and the relationship between the efficiency and the output power is plotted. The efficiency value when the rated output power is checked on the curve is “full load efficiency”.
Usually, the relevant data at the rated voltage and frequency obtained during the calculation process are also used, and the input current, the input power, the output torque, the slip ratio (or the rotational speed), etc. are plotted in the same coordinate system as the above-mentioned efficiency curve. The power relationship curve, that is, the "motor operating characteristic curve".
Source and processing of required data
When adopting this method, the key is to obtain five kinds of loss values under different sets of load at rated voltage and frequency through relevant tests, namely stator copper loss, rotor copper loss, core loss (referred to as "iron consumption"), mechanical Loss and stray loss.
