Every new multi-storey building has an elevator, which is a potential gold mine for electricians. David Herres explains the ups and downs of elevator maintenance and repair work.

Electricians can do very well for themselves (financially as well as in other ways), but there are times when they are subject to fluctuations in the world economy. For this reason we look to enhance our revenue streams.

A significant benefit of being an electrician/electronics technician is that we make our living not by lugging bags of cement or climbing on a roof, but more by the knowledge and expertise that can be deployed in problem solving. This is precisely the situation when troubleshooting and repairing elevators that are not working.

Typically, elevator malfunctions occur at busy times of the day. Passengers can be somewhat inconvenienced, if not stranded completely between floors in an elevator car. The situation is critical, and it is usually the onsite electrician who is called upon to make the initial assessment and decide whether it is necessary to call in a specialised elevator technician.

Of course, this can be an expensive and time-consuming alternative, so it is appropriate for the working electrician to become familiar with elevator technology. Moreover, many elevator technicians are first and foremost electricians. They have expanded their operation to include this (at one time) demanding and rewarding specialty.

Elevator electro-mechanical systems are quite complex. The technician must be a bit of a computer enthusiast, part old-time blacksmith, adept at reading blueprints and schematics, and above all have faith that electrical and mechanical problems can be quickly rationalised and repaired so that they do not recur.

Always, the foremost issue is safety, and there is a long tradition in the trade that design and installation workmanship must be impeccable. Accidents are rare, but when they do occur we are appalled. For each passenger-hour (or whatever metric is used) the accident rate is far less than for motorists on a highway. Most people in an urban setting think nothing of stepping into one of these panelled boxes with automatic closing and locking doors, and hurtling upward to get to their office or to their home in a high-rise apartment.

In the background, the elevator mechanic is an unseen presence, but the reality is that the lives of passengers and co-workers depend upon this technician’s knowledge and integrity.

Over the years, elevator technology has evolved, driven by diverse developments in motors and semiconductors. For many decades in the 19th and 20th centuries DC motors were dominant. The motor controller was a human operator, who varied the voltage level and polarity to determine motor speed and direction. Even after Nikola Tesla and George Westinghouse introduced the induction motor and an AC generation and distribution system that made it possible, DC motors persisted in many applications, notably elevators. That is because they exhibited the smooth, reliable speed regulation that is necessary so that the car can slow down before stopping at each landing. A slow speed is also required for inspection mode, for testing and repair. Frequent reversals of direction are accomplished by simple switching rather than an expensive gear box.

DC motors required regular maintenance, primarily changing brushes at frequent intervals so that the commutator would not be damaged. Onsite electricians could do this work, and a good portion of other upkeep was electrical in nature. Around the middle of the 20th century, revolutionary changes took place and elevator technology became more efficient and safer, yet more high tech.

Still, elevator design, installation, repair and maintenance remained overwhelmingly electrical.

There were two major developments. New equipment and protocols emerged, which permitted the speed of AC induction as well as synchronous motors to be regulated. Unlike a DC motor, an AC motor’s speed is dependent not upon the voltage, but rather upon the frequency of the power supply. True, you can reduce the RPM by lowering the input voltage and thus the magnetic output of the stator windings, but this is not a good way to control the speed of an AC motor. The effect is to overload the motor so that the windings produce heat rather than a magnetic field.

The invention in the mid-20th century of the variable frequency drive (VFD) made possible continuous, smooth speed control of an AC motor by means of varying the frequency at the motor input terminals. It even became possible to apply higher than line frequency so that the motor would run faster than nameplate RPM, limited by the capability of the bearings. This technology can be applied to an existing three-phase induction motor, the only hitch being that if there is an internal fan attached to the shaft, at lower speed the motor may require auxiliary cooling. DC motors are still used, even in new installations, but VFDs are currently dominant for elevators and most other industrial applications where speed, direction of rotation and other control, diagnostics and an advanced user interface are desired.

Aside from motors, the other revolutionary change that occurred during the same time frame was the implementation of digital technology, facilitated by the appearance of inexpensive and reliable semiconductors – first transistors and then integrated circuits (ICs).

Most people, when they think of an elevator, picture only the car and perhaps the call buttons on the wall at each landing. What they do not see is the shaft and pit below the car at the bottom of its travel. Also, there is usually a machine room at the bottom floor adjacent to the shaft. It contains the motor, VFD, mechanism for spooling the cable to raise and lower the car and counterweight, or alternatively, for a hydraulic system, mechanical linkage and hydraulic pump together with a large oil reservoir.

Dominating this machine room is the brooding, hyper-alert presence of the motion controller. It usually takes the form of a floor-to-ceiling steel enclosure with a glass door that can be opened for access to incoming three-phase power conductors together with an equipment ground, several large circuit boards containing rows of ICs together with numerous discrete components and a robust user interface. This will consist of an alphanumeric display and a touchpad keyboard. Also within the motion controller enclosure will be a large transformer with electrolytic capacitors and heavy conductors exiting through raceway to power the elevator motor. To be appreciated, the motion controller must be seen. It is the place to start if you aspire to elevator servicing.

Typically, the first and only sign that something has gone wrong is that the elevator car stops abruptly because the supply of power to the motor has been interrupted. Don’t worry, the car won’t fall to the bottom of the shaft resulting in carnage. That eventuality was prevented by an invention in 1853 by Elisha Otis of a safety device that prevents the car from falling even if the lift cable is severed.

Nor will the car occupants suffocate from lack of oxygen because there is sufficient space between the car and shaft to provide adequate ventilation. When a car stops because the motion controller has cut power to the motor, the passengers must be evacuated from the car. This process is known in the trade as an extraction. Some elevator servicing firms state prominently on their webpages that facility personnel should not attempt an extraction, instead to call the licensed professionals. This sounds prudent, but does not take notice of the fact that an extended delay, especially if the elevator technicians have to travel a great distance, could be highly stressful and even a threat to the health of vulnerable individuals. It is a judgment that must be made, preferably well in advance so that a policy can be in place before the incident occurs.

In order to obtain access to an immobile elevator car, it is necessary first to open the outer door at the nearest landing. This door is self-locking and if it fails to close and lock properly, the car will not move due to a safety mechanism within the motion controller. To open the outer door, there is a proprietary key that must be inserted into a hole near the top of the door and turned in a certain way to release the lock. The key is usually kept in the machine room, which itself must be unlocked by means of still another key. It is important that the whole procedure be practiced in advance so that this part of the extraction can take place efficiently. Finally, after access has been gained, if the car is not lined up with the door opening at the landing, it will be necessary to put a step ladder in place to get the passengers out.

Some individuals may be fearful that the car will start to move, crushing them as they pass through the opening. This cannot happen because the car cannot move when the door is open, but it would be prudent as a backup measure to lock out the power feeding the motion controller and elevator motor within the machine room. Most elevator outages do not require an extraction because either there is no one aboard or because the problem can be solved quickly.

A motion controller in many ways resembles a desktop computer. When it goes down, or crashes, it has to be reset and then it takes about a minute to reboot. On the main circuit board adjacent to the display, typically there is a very small reset button. Press it momentarily and the motion controller will reboot. (Cutting the main power feed at the disconnect where the power enters the machine room will accomplish the same thing.)

Afterwards, if the operation succeeds, the motor will start, moving the car as required, or it will await the next user command. The alphanumeric readout will display the name of the elevator manufacturer or some other comforting message such as ‘System is Operational’. If the defect has not been corrected, the readout will display an error code such as ‘E-4’. If this is the case, it will be necessary to refer to the operator’s manual to ascertain the problem and recommended remedy. The operator’s manual for most motion controllers is available for free download at the manufacturer’s website. Copies should be printed and kept in the machine room and maintenance shop.

A good start for learning the elevator technician trade is to collect and study the operator’s, installation and service manuals of various manufacturers as well as any codes that are applicable in the jurisdiction.

If you are an experienced electrician who likes to do quality work and if you have good computer and mechanical skills, elevator work may have a place in your future.