Course 106 HVAC Systems Introduction and Overview Module 1: Overview of Rail Car HVAC and General Safety Procedures INSTRUCTOR GUIDE
Table of Contents CHECKLIST FOR INSTRUCTION... 3 SUPPLIES, AUDIO-VISUAL EQUIPMENT, INTERNET ACCESS... 3 BEST PRACTICES FOR DELIVERING TRAINING... 4 OVERVIEW TO COURSE 206... 5 MATERIALS FOR INSTRUCTION... 5 COURSE 206 ASSESSMENTS... 5 OVERVIEW TO MODULE 1... 6 Videos, Handouts, Job Aids, Take-aways... 6 Outline of PowerPoint Presentation... 6 Learning Objectives for Module 1... 6 Overview... 7 Motors in HVAC... 11 Phases of Power... 13 Major Components of DC and AC Motors... 17 Thermal Overload Relay Protection... 24 HVAC Motor Preventive Maintenance and Inspection... 29 Field Trip... 39 Summary and Quiz... 40 Page 2
Checklist for Instruction Confirm the training dates, location, and number of participants. Ensure you have all materials listed in the section Materials for Instruction. Ensure you have all that is listed in the section Supplies, Audio-Visual Equipment, Internet Access. Read and study the Instructor Guide, PowerPoint presentation, and any State or local documentation pertaining to the local environment. If using case studies, review ahead of time and select the most appropriate cases studies for your audience. Familiarize yourself with the Participant Guide or coursebook. Collaborate with local host/coordinator to determine who will print the following (available on website): Certification of completion for each participant. Supplies, Audio-Visual Equipment, Internet Access The following is important for the adequate delivery of this course: LCD projector compatible with a notebook computer and cables for proper connection Computer with software to run Microsoft PowerPoint Electronic remote device to advance slides in PowerPoint presentation, if available Projection screen (at least 6 x 6 ) Pointer (preferably laser type) Twenty-foot or longer extension cord Dry erase board with dry erase markers and eraser, if available Flip chart with markers Supplies such as pencils, note pads, markers, highlighters. Access to lab, rail car shop, rail car for hands-on lessons You may need Internet access. All equipment should be placed and tested in the room. The instructor should check at least one hour prior to the first day of the course. Page 3
Overview to Module 1 Duration of this module: 185 minutes (3 hours including field trip) PowerPoint slides: 27 This module has a quiz. Videos, Handouts, Job Aids, Take-aways Links to one (1) Vimeo video is made available to enhance participants learning: Video Rail HVAC Overview The Instructor should bring the following materials/equipment if applicable: Property-specific Safety Data Sheets. Property-specific Personal Protection Equipment Property-specific Lockout/Tagout Kits Property-specific job cards Outline of PowerPoint Presentation Topic Title Slides Duration (Minutes) Overview 1-4 5 5-6 10 7-9 10 10-14 25 15-18 15 19-24 45 Field Trip 25 60 Summary and Quiz 26-27 15 Learning Objectives for Module 1 185 minutes (3 hours including Field Trip) Following the completion of this module, the rail car technician should be able to: Demonstrate knowledge of Clean Air Act of 1990, EPA 608 Certification, Refrigerant Hazards and Proper Handling Techniques Explain types and use of Personal Protective Equipment (PPE) when dealing with HVAC systems List safety rules related to HVAC maintenance Page 6
Motors in HVAC Slide 5 Rail Car HVAC Motors Evaporator Blower Motor Thermo King Evaporator Blower Motor Electric Rail Car HVAC Motors Compressor Motor Assembly Thermo King Condenser Blower Motor INSTRUCTIONAL ACTIVITY: Overview of HVAC Motors in transit rail TIME: 5 minutes INSTRUCTION METHOD: Lecture SAY: Electric motors are used to turn the prime movers of air, water, and refrigerant, which are the fans, pumps, and compressors. These motors provide the speed, torque, and horsepower necessary to operate the application. The motor changes one form of energy (electrical) to rotational or linear motion (mechanical). AC and DC motors are the two major types in use today that are related to the industrial HVAC applications. In rail car HVAC units, AC motors are generally used in newer equipment. Some systems have retrofitted their motors from DC to AC in recent years. To understand the differences of AC and DC motors, it is important to first review different phases of power. ONLY 5 PARTICIPANT GUIDE (COURSEBOOK) PAGE REFERENCE: ADVANCE SLIDE PREVIEW Page 11
Major Components of DC and AC Motors Slide 10 Components of DC Motors Armature Field Winding Commutator Brushes INSTRUCTIONAL ACTIVITY: Explain definition and components of a DC motor TIME: 5 minutes INSTRUCTION METHOD: Lecture SAY: A DC motor is any of a class of electrical machines that converts direct current electrical power into mechanical power. The two major components of a DC motor are the armature (top figure) and field winding. The armature is the rotating part that is physically connected to the shaft and develops magnetic flux around its windings. The field winding is the part of the stationary frame and provides the flux necessary to interact with the armature flux to produce rotation. The commutator (Bottom right figure) acts as an electrical switch and always ensures that a repelling force is present between the armature and field flux circuits. This repelling force against the field winding flux causes rotation of the armature. Brushes (Bottom left figure) are the devices that physically connect the voltage supply to the armature circuit. Brushes are constructed of carbon material and require routine maintenance or replacement to reduce arcing at the commutator segments. For maintenance purposes, this is the biggest difference between DC motors and AC ones, which do not contain brushes. 10 Page 17
Thermal Overload Relay Protection Slide 15 Thermal Overload Relay Protection The compressors, condenser fan motors, and evaporator fan motors are protected by external thermal overload relays, which are combined with circuit breakers. They are protective devices designed to cut power if the motor draws too much current for an extended period of time. To accomplish this, thermal overload relays contain a normally closed (NC) relay. When excessive current flows through the motor circuit, the relay opens due to increased motor temperature, relay temperature, or sensed overload current, depending on the relay type. INSTRUCTIONAL ACTIVITY: Explain definition and function of Thermal Overload Relay Protection TIME: 2 minutes INSTRUCTION METHOD: Lecture SAY: Thermal overload relays are similar to circuit breakers in construction and use, but most circuit breakers differ in that they interrupt the circuit if overload occurs even for an instant. Thermal overload relays are conversely designed to measure a motor's heating profile; therefore, overload must occur for an extended period before the circuit is interrupted. ONLY PARTICIPANT GUIDE (COURSEBOOK) PAGE REFERENCE: 15 Other Tools/Media/Materials: Bring a property specific Thermal Overload Relay Protection and explain its mechanism. ADVANCE SLIDE PREVIEW Page 24
Slide 17 Thermal Overload Relay Protection INSTRUCTIONAL ACTIVITY: Present content with video TIME: 1 minute INSTRUCTION METHOD: Multimedia SAY: Let s take a look at this short video on how a bimetallic switch works. This video illustrates the use of bimetallic switch, with the bimetallic strip highlighted in the middle of the video. When the flame is applied to the switch, the strip bends and the switch opens. Note that when the strip cools, the strip returns to its original position and the switch closes. Other Tools/Media/Materials: Play Youtube video ADVANCE SLIDE PREVIEW ONLY 17 Page 27
Slide 20 HVAC Motor Preventive Maintenance and Inspection Basic Guidelines to Motor Maintenance (2) Motor mount inspection Motor temperature control Record keeping INSTRUCTIONAL ACTIVITY: Explain Motor PM and Inspection Procedures TIME: 5 minutes INSTRUCTION METHOD: Lecture with hands-on demonstration in lab or during field trip SAY: Motor mount inspection. Check mounting bolts, steel base plates for possible warping. Annually, perform vibration-analysis tests. Excessive vibration may be hard to detect by hand, but it could be enough to shorten motor life significantly. It can cause bearing failure, metal fatigue of parts, or failure of windings. The cause of vibration is usually mechanical in nature, such as excessive belt tension, defective sleeve or ball bearings, misalignment, or improper balance. The most common cause is the unbalance of a rotating member (the motor rotor, rotating load, or other drive train component). Electrical problems also can cause vibration. Simple testing of the motor is done by uncoupling the load and then running the motor and listening to the motor noise and feeling for the vibration. Motor temperature control. Restricted ventilation will cause a motor to operate at a higher than desired temperature. Excessive ambient temperatures will shorten motor life. 20 Page 31
Slide 21 Motor Inspection and Maintenance Classroom Activity Work in pairs or small groups. Based on the OEM manual or agency operating procedures, what are your agency s procedures for HVAC motor inspection and maintenance activities and schedule? You have 10 minutes INSTRUCTIONAL EVENTS: Elicit performance TIME: 12 minutes DO: Have participants work with a partner to work on Classroom Activity 1 in their coursebook giving them 10 minutes to complete this activity. Once completed ask each group to volunteer their answers. PARTICIPANT GUIDE (COURSEBOOK) PAGE REFERENCE: ADVANCE SLIDE 21 Page 33
Testing Current Draw: To test the current, or amperage, draw, the motor must be operated. The most convenient way to check the amperage is to use a clamp-on ammeter. With the motor running under a normal load, check the amperage draw of each power line, or leg. Since the current draw may vary slightly over time, you may want to take several readings and then average the data. To obtain an average, record several amp readings at one-minute intervals. Next, add the amp readings together and divide that number by the number of readings taken. After testing each leg, compare the amperage draw data to the amperage information on the nameplate or in the operating maintenance logs. Testing Continuity Using Meters: Using a multimeter set for resistance checking is a convenient way to check continuity. Remember that any time a multimeter is used for continuity testing the device being tested must be deenergized. To test a motor for continuity, first isolate, or disconnect, it from the circuit. Then use the multimeter to check the resistance between phases. Most transit agencies use multimeters for this test rather than the test lamps. Testing for Shorts and Grounds Using Meters: Use a Megohmmeter or a multimeter to test for a grounded motor. Set the meter for resistance testing, and connect one lead to the motor housing, or frame. Next connect the other lead to a winding. If the winding is grounded, the meter will indicate a low resistance. Testing Phase Rotation: Before the initial start-up of a large motor, make sure the motor is turning in the proper direction by simple observation or an air flow check. If the meter indicates that the motor is turning in the wrong direction, check to make sure that all connected elements, such as transformers and branch circuits, are connected correctly. If all connections are correct, check the individual phases of the motor. PARTICIPANT GUIDE (COURSEBOOK) PAGE REFERENCE: ADVANCE SLIDE Page 37
Field Trip Slide 25 Time for a Field Trip INSTRUCTIONAL EVENTS: Hands-on Learning TIME: 60 minutes DO: Have the participants make a list of the components that they d like to see in the field. Ask one participant to scribe on a whiteboard/flip chart. Take the group into the field and ask them to explain what they see helping with identification/explanation as needed. ADVANCE SLIDE Page 39