Using Programmable Logic Controllers to Simulate Common Motor Load Curves in Industry

This paper addresses the need to simulate in laboratory, realistic load torque-speed curve profiles encountered in industry. Such an objective matches certain training requirements for students attending technology diploma and/or undergraduate engineering programs. The versatility of the lab equipment allowed the inscription of the motor load curves into the memory of a variable frequency drive converter (VFD, particularly of Allen-Bradley Power Flex70 type) and of a four quadrant drive (4QD, particularly of Allen-Bradley Power Flex DC type) through a Programmable Logical Controller (PLC, of Allen-Bradley type). Both converters, VFD, respectively 4QD communicated with the PLC through an Ethernet switch, and operated an induction motor (IM) and a DC generator, the last one playing the character of load emulator. Real time information about the IM and DC machine came into the PLC inputs. The system was able to simulate the "Linear", "Quadratic", and "Cubic" load models, with results verified through the "Trending" function in PLC software Studio5000. On top of successful experiments, resulted one installation manual, one user manual for the experimental stand, and several lab procedures, projected to guide future students attending engineering technology/undergraduate engineering on how to operate this experimental stand.