HRAC 211 Lab 07 Pressure Transducers

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Centennial College *

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211

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Electrical Engineering

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Jan 9, 2024

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Centennial College HRAC 211 - Lab 7 Pressure Transducers Name (Please Print): Gurman Lohcham Student Number: 301271950 Class Number: HRAC 211 - Date: Week 7 - Lab 7 Pressure Transducers Please Read Unit 25, Special Refrigeration Components, Section 25.21 Oil Pressure Safety Control Pressure Transducers take a pressure reading and coverts it into an electric signal (analogue) and allows input into devices to allow control to take place. As pictured below inserted into this Copeland Compressor is an Oil Pressure Safety Sensor. Microprocessors, like the one pictured below, to the right, have a built in analogue to digital converter to allow direct digital control.

P a g e | 2 Objective: To understand the relationship of a pressure transducer and the voltage output that occurs when pressure is applied to the device. Again, Please Read Unit 25, Special Refrigeration Components, Section 25.21, Oil Pressure Safety Control Materials Required: DC power supply Electronic refrigeration manifold gauges Pressure transducer Vacuum pump with fresh vacuum pump oil Nitrogen cylinder complete with regulator Methodology: 1. Determine the positive, negative and output terminals of the sensor. Connect to the power supply. Connect the output to the positive terminal of the meter and the negative side of the meter to the negative of the power supply. 2. Determine the lowest vacuum pressure and highest pressure that can be used on the transducer. 3. Attach the vacuum pump to the manifold and the sensor. 4. Adjust the vacuum pump air ballast screw to obtain the required vacuum pressure. Record the pressure and the output voltage on the table. Step the readings every 5” of vacuum. 5. Attach the nitrogen cylinder with regulator to the refrigerant manifold in place of the vacuum pump. Starting at 0 psig, record Centennial College - SDRE

P a g e | 3 the voltage of the output. Step the pressure 10 psig and record the output voltage. Do not exceed the maximum working pressure of the transducer. Record your readings on the table below. Centennial College - SDRE

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P a g e | 4 Pressure Unit Voltage 0 Psig 0 10 Psig 0.58 20 Psig 0.68 30 Psig 0.76 40 Psig 0.85 50 Psig 0.92 60 Psig 0.99 70 Psig 1.07 80 Psig 1.15 90 Psig 1.23 100 Psig 1.32 110 Psig 1.4 120 Psig 1.47 130 Psig 1.55 140 Psig 1.64 150 Psig 1.72 160 Psig 1.8 170 Psig 1.88 180 Psig 1.96 6. Using Microsoft Excel, record your findings in table and use the program to generate a simple graph of your observations. Submit a print of the table and the graph with this lab. Independent Research Centennial College - SDRE

P a g e | 5 Research pressure transducers: 1. How do pressure transducers work? What causes the changes necessary for them to operate? - Pressure transducers are devices that measure pressure by generating electrical signals in response to applied pressure. Centennial College - SDRE

P a g e | 6 2. Please write down the step x step - correct chronological order of operation - of the below pictured oil pressure safety controller. Centennial College - SDRE

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P a g e | 7 2 Continued Please write down the step x step - correct chronological order of operation - of the below pictured oil pressure safety controller: … from the time of: A - initiation of the HEATER until the all clear, continue running is initiated, and B – initiation of the HEATER until a full stop is initiated. A/ - compressor starts - time delay heater is energized - net oil pressure value rises until set value for “heater off” is met - time delay heater is de-energized and compressor continues to operate - B/ net oil pressure value decreases below “heater on” setting during running cycle - time delay heater is energized - if net oil pressure does not rise above “heater off” setting compressor shuts down Centennial College - SDRE

P a g e | 8 3 Research enthalpy sensors used in the Economizer Sections of Air Conditioning Systems. (Fresh Air, Mixed Air, Free Cooling Damper System) Please explain what setting you would suggest your client use, in order to have “Free Cooling” during the months of Fall and Spring. Your client is located downtown Toronto, Ontario, Canada. Research Unit 50 in your Text – 50.4 - Economizer Modes of Operation. - Your Answer to 3 Here You can get "free cooling" by installing an automatic thermostat that turns off the system to save money. When the outside air is identified to be colder than the inside air and the system is calling for cooling, the system will let the colder outside air in. Centennial College - SDRE

P a g e | 9 4 Advise the difference between SPDT contacts and proportional control. SPDT stands for Single Pole Double Throw, and it refers to a switch that can touch either one ordinarily open or one normally closed terminal. Proportional controls, on the other hand, alter the output based on the input values. Lab 07 For Full Marks hand your completed Lab in before leaving today. For no greater than a B+ you may hand in your completed Lab 07 at the beginning of the following standard school week. Late labs will not be accepted and will receive a Zero Grade Scoring Safety In Lab ….. 25% Participation In Lab 25% Centennial College - SDRE

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P a g e | 10 Completion Of Lab And Submitted On Time 50% Total Best Score Submitted On Time 100% Total Best Score For Late Submission 75% Centennial College - SDRE