Study Questions
CHAPTER 4
Advanced Motor Repair
What It Takes
Some Examples
Surge Testing
Core-Loss Test
Detecting and Analyzing Motor Vibration
Bearing Maintenance
More on Vibration Analysis
Hydraulic Rope Equalizers
Passenger Rescue from a Stuck Car
Traveling Cable
Lubrication and Oil Analysis
Study Questions
CHAPTER 5
Troubleshooting Elevator Systems
Study Questions
CHAPTER 6
Electrical Troubleshooting Tools and Instruments
Test Lights
Multimeters
Non-Contact Meters
Power Quality Measurements
Oscilloscopes
PC Based Spectrum Analyzer
Thermal Imager
Study Questions
CHAPTER 7
Measuring Power Quality: How It May Be Improved
Three-Phase Configurations
Total Harmonic Distortion Measurements
Catastrophic Transformer Failure
Costly Harmonics
Power Factor
What’s All This About Sine Waves?
Three-Phase Motors
Oscilloscope
Fourier Transform
Study Questions
CHAPTER 8
Elevator System Overview
National Electrical Code
Study Questions
CHAPTER 9
Motion Controller
Programmable Logic Controllers
Specific Operating Modes
Car Top Operating Station
Study Questions
CHAPTER 10
Systems Connected to Elevator Installations and How They Work in Concert
Emergency Power
Tests and Maintenance
Normal Electrical System
Wiring Methods for Elevator Shafts, Pits, and Machine Rooms
Study Questions
APPENDIX A
Study Questions Answers
APPENDIX B
Electrical Laws and Equations
Index
An appropriate subtitle for this introduction would be: DON’T GET IN OVER YOUR HEAD! Elevators move large numbers of people up and down in high-rise buildings on a daily basis and there is the potential for an accident to occur. A highly-developed system of safeguards is in place, and for this reason an elevator ride is statistically far less hazardous than crossing a street.
Fatalities are extremely rare due to the redundant safety mechanisms, but they have occurred, some because of faulty maintenance procedures. A documented instance involved two wires which were temporarily disconnected from a circuit board and then reversed, thus disabling the door interlock, which prevents an elevator car from moving when the door is not closed and latched. A child was crushed between the car floor and door opening. There are tremendous moral and legal issues, and it is the responsibility of each worker to understand the consequences of any errors.
In the popular imagination, if an elevator cable breaks, the car immediately falls to the bottom of the shaft, killing the occupants. In actuality, the car is connected by multiple cables, which are regularly inspected for wear, any one of which would hold a fully-loaded car. Additionally, elevator cars have mechanisms known as safeties, which clamp onto the guide rails in an overspeeding or slack-cable situation.
In performing elevator maintenance and repair, there are enormous moral and legal issues. Workers need to fully understand proper maintenance procedures so that all safeguards remain in effect. As a start, it is essential to become aware of applicable regulations and to comply with them.
Of course, a major aspect in elevator technology is electrical. The National Electrical Code (NEC), revised and issued every three years by the National Fire Protection Association (NFPA), governs most electrical installations with a few exceptions such as installations under the direct control of utilities, and underground in mines. (It does, however, govern non-mine installations such as lighting and signal wiring in underground traffic tunnels.) NEC has no legal standing on its own, but is offered up for adoption and enforcement by states, municipalities, and jurisdictions inside and outside the United States.
NEC Article 620, part of Chapter 6, covers elevators, dumbwaiters, escalators, moving walks, platform lifts, and stairway lifts. Each of these performs a different set of functions with different requirements. The section on elevators contains specific electrical requirements, which must be observed in new installations. It is not the intent of NEC that with each Code revision all existing installations are to be immediately upgraded to comply. Nevertheless, older installations should be critically evaluated to see where upgrades are feasible and/or warranted. Besides Article 620, new elevator installations must comply with the entire electrical code except where specifically exempted. Two very important articles are 250, Grounding, and 430, Motors, Motor Circuits and Controllers.
I will return to the very important subject of codes in this Introduction and in fact throughout the book, but first a few paragraphs about licensing.
If you are serious about engaging in elevator work, you should acquire the appropriate license(s)—electrician’s license and elevator mechanic’s license. This is not going to happen all at once. Most states require verified work experience and/ or completion of classroom or online training, including passage of an exam, plus the state exam. There is no single nationwide electrician’s or elevator technician’s license. For the most part in the United States these permits are issued and regulated by the individual states, or in a few instances jurisdiction is ceded over to separate counties or municipalities. Most states maintain electrical and elevator agencies, which inspect installations and issue technicians’ and other permits. Requirements vary widely from state to state. The best approach as a start is to check your state’s website for requirements and procedures for obtaining the appropriate licenses.
My home state, New Hampshire, requires electricians’ licensing for those who are performing electrical installations