Power measurements and start-up of a MAS
This section introduces us to the operation and analysis of asynchronous motors, which are
widely used in industrial applications. Our tasks involve assembling and modifying the
motor's circuit, starting the motor, and performing electrical power measurements. Key
tools utilized include a wattmeter for measuring power consumption, a torque meter to
monitor the motor's load, and voltage probes for capturing phase voltages.
Once the motor is operational, we record the line currents, phase-to-phase voltages, and
electrical power transmitted to the motor. Using these measurements, we calculate
essential performance metrics such as active power, power factor, reactive power, and
overall motor efficiency. To visualize the power relationships, we draw the power triangle.
This part of the study helps us connect theoretical concepts like power analysis and
efficiency with practical experience. By working with real motor systems and components,
we gain hands-on skills in handling industrial equipment while ensuring safety protocols are
strictly followed.
The below diagram shows the connections that have been done to us to be able to measure
the of the source
And bellow we can see the connection in the motor
And at N.m Torque the mesureaments are as show in the bellow iumage and table
In the Mod Meca we can read the Useful power of the motor, the motor speed and the
torque is set at N.m
For the measurements of the Line of the moto the wattmeter was used and we measured
the voltage, Current and Active Power lowing in the line and all results are shown in the
bellow table
Measured Value Unit
I 2.33 A
U 405 V
P 1.05 kW
Pu 0.775 kW
T 5 N.m
n 1469 rpm
With the quantities measured we can determine:
Active Power
The active power was measured in the system using then wattmeter P=1.05kW
Power Factor
For the Power factor calculation we need to determine the apparent power first and, then using the
below formula and steps the PF was calculated.
𝑃 (1.05 ∙ 10 𝑊)
𝑃𝐹 = = = 0.642
𝑆 √3 ∙ (405𝑉) ∙ (2.33𝐴)
cos 𝜑 = 0.642
𝜑 = 50.058°
Reactive power
The reactive power was determined from the active power and the result is shown below:
𝑄 = 𝑃 ∙ tan 𝜑 = 1.05 ∙ 10 ∙ tan(50.058°) = 1253.916 𝑘𝑉𝐴𝑅
Motor efficiency
The motor efficiency can be determined as we know the useful power and the active power
consumed by the motor and the result is shown bellow:
𝑃𝑢 (775𝑊)
𝜂 = = = 0.738
𝑃 (1.05 ∙ 10 𝑊)
Conclusion
The Phase voltage measured was around 405 V an the expected Voltage was of 400V , so its pretty
tolerable and the value is okay, for the current we found 2.33 A and its also a acceptable result, or
the active power in the line 1 we measured 1.05kW and this value is okay and expected fo the test at
low torque , the power factor was determined and we found that is equal to 0.642 this owas also
expected the Reactive power is equal to 1.253 kVAR and also this value is pretty acceptable,
regarding the motor efficiency the calculated efficiency was around 73.8% this efficiency seems a
little bit low but it can be explained by the fact that the motor is working at low torque, as we know
that the motor is more efficiency at a little bit high torques.
