MECH 366 midterm cheat sheat

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Electrical Engineering

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Jan 9, 2024

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Which following communication protocols is not single master, multiple slave? EtherNet/IP Which protocol transmits both analog and digital data over the same wires? d) HART Why do industrial digital communication protocols use twisted pair cables? b) Better noise immunity Which of the following industrial protocols requires extensive cybersecurity hardening? b) EtherNet/IP There is food grade deionized water flowing through a pipe with an internal diameter of 3 cm. There is a risk of a partially filled pipe scenario. What flow metering technology do you use and why? Ultrasonic as electromagnetic metering requires ions, and turbine can’t detect partially filled pipes Assuming you measure a fluid velocity of 0.5 m/s, what is the mass flow rate A = pi * r2 = 3.1415 * (1.5)2 = 7.068375 cm2 Mass flow rate = A * v * d = (7.068375 cm2) * 50 cm/s * 1.00 g/cm3 = 353.4 g/s What signaling would you use to convey fluid velocity to the PLC and why? How would you determine total volume of fluid through the pipe over 24 hours of operation as accurately as possible within your PLC? - 4-20 mA signaling to minimize error due to signal loss and noise. - HART protocol to transmit volume. 0.5 marks if they propose integrating flow rate in the PLC. Provide three benefits and risks of integrating a control network with Cloud Benefits: • Use established technology preconfigured for the application • Less computing hardware to manage • Data backed up off site, • Premade analytics, big data Risks • Sharing data with a third party • Exposing control network to the Internet (even indirectly) • Excessive latency, • Communication failure Describe the responsibilities of a project manager within a project team and contrast the role with a technical publications lead. Project manager: • Budgets and finances, Timelines and milestones, Oversees staff Engages with other management to remove barriers for project success • Responsible for project pacing and overall success Technical publications lead: • Documentation and communications expert • Oversees design/product documentation and reporting • Translate technical material into language appropriate to the audience Accuracy: Definition: Proximity of measured values to the true value Example: Inaccurate temperature readings in a pharmaceutical storage facility can compromise medication effectiveness. Precision: Definition: Consistency in repeated measurements. Example: Inconsistent pressure readings from a sensor can disrupt precise control in industrial processes. Resolution: Definition: Smallest detectable change in input. Example: A low-resolution laboratory scale may fail to accurately measure small weight changes in experiments. Drift: Definition: Gradual change in sensor output over time. Example: Drift in a medical oxygen sensor can lead to incorrect adjustments, posing risks to patients. Which of the following enables an electric motor ramp to maximum speed and controlled ramp to stop? d) VFD with a brake 2. Which of the following is not a benefit of VFDs vs. across the line starters? a) Increased harmonics 3. What additional hardware is required for VFD constant torque vector.control? c) Rotary encoder for speed measurement 4. VFDs are designed to operate with what type of motors? a) Induction machines Contrast the role of SCADA systems and HMI panels in automation designs. • HMI panels are dedicated, screens mounted directly to control panels. SCADA systems tend to be computers located in a central command room. • SCADA systems are more comprehensive and powerful than HMI screens. • A control system may have multiple HMI units but typically only one SCADA. • SCADA provides centralized alarm and historian services. What role does a historian...digital control system?: Data storage, Data analytics Which of the following is not a permissive for a conveyor belt system? b) Object ready for conveyance 2. Permissives should be described in detail in b) Controls narrative Typical PLC input signals used by permissives (e.g. sensor fault) should normally be wired c) To a PLC input in a normally closed configuration

4. When any of several sensors of the same type, should cause a device permissive to fail then a) They can be wired in series with each other to conserve I/O Consider a molten salt battery plant. You are automating the process which starts and stop the pouring of 200 kg of 400ºC molten salts into individual battery cells, which are positioned by a single axis conveyor. The process is responsible for starting and stopping pouring, signaling when the cell is complete, and operator and system safety around the pouring station. Some combination of the following with reasonable explanations required: • Cell mass measurement (strain-based load cell),• Cell position using ultrasonic or other non-contact technology,• Ambient temperature,• Spill detection (thermal, electrochemical, etc.),•Emergency stop Actuators:,• Conveyor across the line starter, contactor driven,• Indicator/Lamp showing that the process is complete,• Pouring controller start/stop A company is consuming an average of 1.2 MW of real power and 0.2 MVAR of reactive power. The main feeder is a 3 phase, delta transformer with a 600 Vrms secondary (output). Three large motors on site require a neutral in addition to the three phases. What would you add to the plant to provide a neutral for these motors? What would the line to neutral voltage be? Add in a Delta-Wye transformer. VLN = VLL / sqrt(3) = 346 Vrms What is the apparent power and power factor of the plant? Is the power factor appropriate for industrial use, or is some form of compensation recommended? Describe how would you compensate for an inappropriate power factor? S = P + jQ = 1.2 MW + j0.2 MVAR = 1.217 MVA : PF = P / S = 0.986 You would add capacitors to the plant to produce reactive power. Power is cheapest at night/mid-day

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