Electrical Design
Human-Machine Interface
The Human-Machine Interface (HMI) was developed to be the main portal of communicationfrom the operator to the system. The HMI was developed with the intention of being concise and easy to use, while offering the operator all the necessary controls to safely and efficiently perform testing. A Siemens model KTP700 Basic Touch-Screen Simatic HMI was chosen as the preferred hardware for this communication.
Siemens S7-1200 PLC
The PLC programming was done in Ladder using SIEMENS TIA Portal to program an S7-1200 PLC. The Ladder code can be broken up into five main sections: start up code, data acquisitionand logging, active stepper motor (flow and expansion valve) control, PID loops, and shut down code.
Electrical Analysis
An electrical analysis was performed on all required components to determine the steady state electrical load. This analysis was used to determine required electrical supply for the system. This analysis is crucial to the design because the overall system had to fit on a 120V 20A circuit.
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Through discussions with the client and strategic planning of electrical components and on/off sequences the team was able to achieve steady-state electrical load under 15A.
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