Page 7 - Industrial Technology EXTRA 1st Febraury 2021

stations at the required speeds.” With
exacting demands in terms of safety
and reliability and the need to maintain
hundreds of escalators any technical
change has significant implications so
the escalator engineers are meticulous
in assessing any new optimisation
opportunities.
The reality is it’s an ongoing process
of modernisation in an environment
that is highly resistant to
standardisation, because after all, the service life of The motor windings can also serve as ‘braking
an escalator is around 30 years. At any one time, resistors’, converting energy into heat, but only to a
multiple generations and models from different limited extent and not continually. It would also be
manufacturers are in use across the network, while possible to supplement an inverter drive with an
the individual spatial conditions are equally diverse. additional regenerative unit, but this is not feasible
Daniel Mayer, responsible for the electro due to limited space in escalator control cabinets.
technology of the escalators says, “In a nutshell,
every system is unique”. MVG tackles this challenge The solution
by drawing on its own powers of innovation, with Eventually a solution was found in the technology
one example being the manufacturer-independent that is still rarely used in low voltage applications, a
escalator control system which they developed matrix converter that combines the inverter and
themselves. This means each escalator can be regenerative unit in a single device. In the spring of
maintained by in-house personnel, faults can be 2016 MVG tested the capability of the few market-
rectified faster and costs for spare parts and ready options available using their own simulator.
conversions are minimised. Among the specific escalator requirements was a
flying start function to ensure synchronised start-up
The benefits of inverter drives after automatic deactivation and all electrical
TMVG has been using inverter drives since before components have to operate year round at outside
the development of the new control system the temperatures.
benefits of which quickly became apparent over Yaskawa’s newly developed U1000 was one of
conventional drives in every day operation on the units tested and as far as MVG were concerned,
upward escalators. The inverter control enables it ticked all the boxes. First introduced by Yaskawa
variable start-up and stopping, which means not in 2014 the U1000 matrix converter is a highly
only more comfort for the users, but also protects efficient, regenerative direct inverter for powering
the mechanisms. However, as impressive these induction and permanent magnet machines, with or
benefits were, MVG had been searching for a without speed sensors.
suitable solution for downward escalators. Today the range covers a wide power range from
While many systems work with conventional 2.2 to 500kW and thanks to its innovative design is
braking resistors, the resulting waste heat has to be capable of direct regeneration and doesn’t require
dissipated safely, not least for fire safety reasons. any DC bus capacitors. No space is needed for an

February 2021 • INDUSTRIAL TECHNOLOGY EXTRA • p7