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Atwell International Limited
The movement detection controls are designed to be installed with new lifts and
retro fitted to existing passenger and goods lifts and used in conjunction with the
bi-directional VG rope brake (VGRB2).
The movement detection controls connect to the main lift control panel. From
here it can receive power and signals to tell if the lift doors are open, or that the
lift over speed governor is OK. It also sends signals to the lift to say stop on next
floor if there is a problem, or emergency stop.
The system will always deploy the brakes immediately and interrupt the main
lift stop circuit, if over speed is signalled or if the emergency stop button on the
front of the panel is pressed.
The movement detector detects movement by looking at an idler wheel resting
on one of the main ropes. As the rope moves so does the idler wheel, and as the
idler wheel rotates movement and direction is detected.
When the doors are open the system is checking for excessive movement.
If excessive movement is detected then the brakes under its control will be
deployed and in addition to this an emergency stop signal will be sent to the
main lift control panel, by means of interrupting the main safety circuit.
There are other functions included with the system such as indication of status
to assist fault finding, resetting of the brakes, manual override to test the
deployment of the brakes, ability to bypass the system (allowing car top control,
without deploying the rope brakes) and pit safety to monitor lift motion when
engineers are in the lift shaft or pit.
Power loss is catered for by the incorporation of an internal battery back-up
system to seamlessly switch from mains power to battery and back again
without the need for manual intervention to reset the brakes. But if during the
power loss excessive movement occurs, or that the over speed governor trips,
the brakes will be deployed and a full reset will be required.
If during its normal operation the system develops a fault then an error or alert
signal will be sent requesting the lift stops at the next floor, doors opened and
stays there until the fault is corrected. During this time whilst the doors are open
the system will continue to detect excessive movement.
Overview
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