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The system is designed to fail-to-safe!

By Mike Cunningham On August 21st, 2017

When a company designs, manufactures and installs an elevator, or what is known in Great Britain as a lift, the interlocks, safety features, set switches and power controls are so secure that they are foolproof. If any switch or safety feature is not working or acting incorrectly, the whole system is designed to fail-to-safety.

The interlocks on the doors are designed so that, if the folding leading edges of the doors touch, impact or foul anything at all, they are designed to return to open status. A second feature, in most modern lifts is either an infra-red or photo-optical switch shining across the door opening, such that if the signal is blocked after the doors begin to close, but before the leading edges touch and lock together, the system is again disabled, the doors return to ‘fully-open’ status.

The speed of the lift is carefully monitored and controlled, and the reigning safety speed features are controlled both by mechanical governors, and electronic detection devices.

Lift companies charge a great deal of cash for their systems, whether it is a high speed elevator in a skyscraper, or a humble lift in a private residence, and they engineer out every possible defect.

So if the printed story is factual, and this unfortunate woman was virtually beheaded when the lift commenced moving while the doors were still open, someone has shorted out the interlock and safety systems; and the charge should be manslaughter, or the Spanish equivalent.

2 Responses to “The system is designed to fail-to-safe!”

  1. I’ve heard of such stories here.

    They’re thankfully rare.

    Let’s see what comes out in the investigation.

  2. That is truly horrific.
    The problem with systems design to be a 100% Fail Safe and foolproof, is that in reality nothing can ever be 100%.

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