Product category:
Industrial Drives/Controls
News Release from: Softstart UK | Subject: Soft Start UK OEM electrical kits
Edited by the Engineeringtalk Editorial
Team on 16 January 2008
Soft starter guard mine against
explosions
An OEM kit of parts supplied by Soft Start UK was used to develop an explosion-proof soft starter for a Russian coal mine.
A Russian coal mine is set to become one of the most technologically advanced in the world, as it prepares to install an explosion-proof soft start, for its massive conveyor system The British-built, explosion-proof soft start unit is rated at 6000V, 800kW and effectively makes the conveyor fully automatic
This article was originally published on Engineeringtalk on 8 Jul 2008 at 8.00am (UK)
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Maintenance costs of over GBP 25,000 per year were being incurred due to the absence of any control when starting-up the cooling fans.
It is designed to simultaneously start three separate motors, each rated at 400kW and run the mine's main gate conveyor which carries coal from the working face to the mine shaft.
It was designed and built by Baldwin and Francis, which specialises in electrical systems for extreme environments, from an OEM kit of parts supplied by Soft Start UK.
The kit consisted of thyristor power modules, a fibre optic EPT for firing the thyristors and an electronic control module and user interface.
Further reading
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Modern soft starters offer virtually all the control features of inverter drives with the exception of speed control of the motor.
DC injection brakes provide dynamic braking
New from Softstart UK is the Solbrake range of DC injection brakes, providing dynamic braking of AC squirrel cage motors from 220-690V.
Baldwin and Francis took these components, built them onto a chassis which was then enclosed in an Ex D housing.
The whole system was custom designed for the installation.
It had to be compact, as space was limited.
This required that the thyristors be supplied with specially-made right-angled couplings rather than conventional in-line ones.
The use of fibre optics electrically isolates the high and low-voltage parts of the soft start and removes the possibility of flashovers.
Cooling of the soft start was a major design consideration so that the electronic components could be used with confidence in such an aggressive environment.
Several options were considered, with forced draught chosen because it would be the most reliable over the expected long working life of the equipment.
Mark Ramsden of Baldwin and Francis explains: "The worldwide mining industry is still fairly new to electronic solutions to do with starting motors underground and we are doing a lot of pioneering work in this respect".
"Electronics tend not to like the heat and gases typically found underground and the thought that they may cause a spark is an anathema to mining engineers the world over".
"It is our job to show that electronics are robust enough and start sparking isn't a problem".
Until four or five years ago all mine-based conveyor starting would have been via a fluid coupling, but the there is now a definite trend to more modern ideas.
Soft Start UK is riding a wave of interest in medium-voltage soft starts, particularly from the heavy and harsh environment industries such as quarrying, groundwater pumping, offshore, waste management and recycling.
The majority of its installations are bespoke and include considerable design input.
Often this leads to specials parts being sourced or made for particular jobs.
Ramsden said "Starting large motors direct on line underground is challenging".
"Often weak reticulation supplies preclude this from happening".
"Soft starting is essential in situations like this and the expertise we can tap into at Soft Start UK is invaluable".
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