Product category:
Proximity Sensors
News Release from: Variohm Eurosensor | Subject: Celesco cable extension position transducers
Edited by the Engineeringtalk Editorial
Team on 07 February 2000
Cable extension transducers make the
Dome safer
Movements of the centrepiece at the Millennium Dome are monitored with position sensors supplied by Variohm Components
The structure used as the centrepiece of the entertainment at the Millennium Dome is believed to be the largest piece of moving stage scenery ever built In order to ensure the safety of the performers and general public its movements are monitored with position sensors supplied by Variohm Components
This article was originally published on Engineeringtalk on 30 Jun 2008 at 8.00am (UK)
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The scenery known as the "Tower of Babel" is normally housed beneath the stage area at the dome's centre.
It isn't a single tower as such but consists of six individual towers linked together by five concentric rings fabricated in steel tubing.
These towers are operated by a complex hydraulic system, which raises the overall structure to a maximum height of almost 30 metres.
Like any moveable structure the overall structure has to be light enough to be moved and yet strong enough to do its job, there is therefore some relative movement between the six lifting towers.
This relative movement isn't critical unless it becomes so large as to cause the whole structure to lean and lose stability.
In order to ensure that the towers extend and retract in a safe manner and even manner the relative positions of all six lifting towers are constantly monitored and controlled to within 1% of each other.
Celesco cable extension position transducers supplied by Variohm Components have been used to measure the height of each lifting tower.
The Celesco units are ideal for this type of application as they take up very little space when retracted but offer extremely long stroke lengths.
They don't require accurate alignment either.
They consist of a stainless steel wire, an accurately machined drum, a reverse wound spring and a sensor (usually a potentiometer).
The stainless steel cable is wound around the drum and as it is extended it causes the drum to rotate.
In rotating the drum tensions the spring and via a set of gears operates the potentiometer.
The relationship between the distance by which the cable is extended and the potentiometer output is a linear one.
The stainless steel cable is tensioned and re-wound by the spring.
On the "Tower of Babel" the transducer bodies are fastened to the bottoms of the lifting towers and the cable to the upper sections as the towers extend the cable is also extended.
The Dome is a very clean environment but Celesco transducers are available which can operate in the most hostile environments.
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