A friend has asked me (I used to work as a librarian) to help him research the basics of electro-mechanical locks as part of a bigger project on EAC systems. The topic is proving harder than I expected. I looked through Bill Philips' "The Complete Book of Locks and Locksmithing" (6th edition), however, he only addresses these types of locks in Chapter 10 on Detention Locks and Hardware while also discussing mechanical locks, and the information doesn't seem to address the basics that are needed.
I'm finding the topic a little confusing, and need help just looking for the basics of -- why are they used? where are they used? how do they work? concerns in using them, any compliance issues, positive/negative aspects, etc.
Any help and resources (online and paper) you can provide is most appreciated.
When electric control of a door is needed -- because you want it remotely openable, because you want it under control of an electronic device such as a card reader, and so on.
See above..
Many types exist. Generally an eletromagnet is activated to either hold or release a piece of metal, which directly or indirectly secures the door.
Fail-safe vs. fail-secure, mechanical requirements, electrical requirements, price vs. robustness, code, local licencing if any... All the same issues as installing other locks and other electrical devices.
If you are talking the kind of electronic lock (e-lock) that replaces a standard mechanical combination lock, I can think of a few things:
E-locks are easier to use. There is no guessing if you got the right number. LaGard e-locks beep twice with a valid combination, 3 times with a bad one. On mechanical combination locks, users sometimes find themselves wondering if the number they dialed in was right on, or a bit off (as in 19, versus 19 1/2)
E-locks are (sometimes) programmable. If you buy an e-lock with just the basic features, if it is programmable, you can change those settings in the future. For example, some places require "dual-control" on locked safes, this to prevent one person from having access to the contents of the safes. An e-lock can be programmed to require two combinations for it to open, it could have a time delay, it could act as a timelock, etc. (or it could do all three- require two combinations, have a time delay, and be a timelock)
There is the obvious downside to an e-lock - they require power to operate. Batteries mostly, except for Kaba-Mas locks where the act of spinning the dial spins a small generator inside the lock, thereby providing enough power for a minute or so.
For very-high-security applications, e-locks do something that mechanical combination locks could never do - the combination required to open them automatically changes after it is opened.
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As for how they work, a LaGard e-lock generally has a small solenoid inside it. When the lock is locked, the pin of the solenoid is stuck out inside the lock bolt, preventing the bolt from being retracted. When a valid combination is entered, the lock's electronics power up the solenoid for a few seconds thereby retracting the solenoid pin, allowing the user to open the lock.
Try looking up some of these books through your local library:
[Or maybe Inter-Library Loan if your local library doesn't have them]
Joe Cieszynski Closed Circuit Television: CCTV Installation, Maintenance and Operation Paperback: 256 pages Publisher: Newnes 2 edition (October 2003) ISBN: 0750657286 List Price: $37.95
Terry Kennedy, John E. Traister Low Voltage Wiring: Security/Fire Alarm Systems Paperback: 400 pages Publisher: McGraw-Hill Professional; 1 edition (August 27, 2001) ISBN: 0071376747 List Price: $39.95
Jim Hayes, Paul Rosenburg Data, Voice, and Video Cabling Paperback: 336 pages Publisher: Thomson Delmar Learning; 2 edition (June 11, 2004) ISBN: 1401827616 List Price: $47.95
Clyde N. Herrick Telecommunications Wiring (3rd Edition) Paperback: 384 pages Publisher: Prentice Hall PTR; 3rd edition (December 15, 2000) ISBN: 0130286966 List Price: $54.99
John L. Schum Locksmithing and Electronic Security Wiring Diagrams Paperback: 275 pages Publisher: McGraw-Hill Professional; 1 edition (March 22, 2002) ISBN: 0071393056 List Price: $34.95
Alan Matchett CCTV for Security Professionals Hardcover: 352 pages Publisher: Butterworth-Heinemann (November 2002) ISBN: 0750673036 List Price: $64.95
You said that your friend was researching Electronic Access Control systems... Well this will help you understand the systems as a whole, as for individual devices you should look up technical information on each device from its manufacturer...
The locks themselves are hardly ever directly connected to the computer that controls them, they are typically wired into local control boxes that handle several devices, that are then networked...
I hope that this information is helpful... Good luck on your search...
Evan, ~~ formerly a maintenance man, now a college student...
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