Steve Hughes Managing Director REO UK
“One of the challenges we faced was
“Our reputation as a reliable drives maker
This process allowed REO to achieve the
fitting the traditionally heavy-duty, large
is very valuable to us and a drive failure
Invertek specification requiring terminals
electrical components into a VSD designed
rate, due to the failure of the choke, of
on the DC link choke to be rated between
for precision motor control,” explained
even 1 in 1000 would not be acceptable.
690-1000V. Had a typical off-the-shelf
Steve Hughes, managing director of REO
We expect absolutely zero failures if we
choke been used in this installation, the
UK. “Because our DC link choke is the last
want to be taken seriously and I’m happy
inadequate standard terminal rating of
component to be fitted into the drive there
to report that, to date, no REO products
500V would most certainly have caused a
is a very low mechanical tolerance. We
have failed.”
failure of the terminals by short-circuiting,
had to ensure that it was easy to integrate
Challenges
resulting in possible fire and subsequent
otherwise the whole drive would require
It wasn’t all plain sailing however. Fulfilling
and increased energy use would have
redesigning.”
the next part of the brief involved ingress
significantly raised costs.
into Invertek’s existing infrastructure,
The solution was two-fold, for the second
prototype copper was used as the winding
injury. At the very least, considerable wear
protection and suitability for worldwide
use. Although headquartered in the UK,
Future innovation
90 per cent of Invertek’s products are
Despite the numerous challenges posed
exported for use around the world. Part of
by a stringent brief, the collaborative
the challenge of manufacturing a VSD for
approach between Invertek and REO
general use is overcoming the challenges
produced not only a reliable product
posed by countries like India where high
but also a sustainable partnership
humidity levels, in addition to supply
between the two companies. Research
issues and an often underdeveloped
and development conducted in both
engineering infrastructure, can quickly
organisations is being used to continue
push components to their limits.
innovation in product development.
customise production-jigs and secure the
Using a potted design, REO enclosed the
“We always aim to use a consultative
choke in the right position onto the bus
DC link choke and was able to make the
approach,” said Steve. “Having finished this
bar.
unit waterproof to an ingress protection
project we’re already working on a cold
rating of IP55. In conjunction with the
weld process that will realise material cost
and terminal material. Because the
purpose of a DC link choke is to provide
smoothing of the current waveform,
reducing the DC bus voltage-ripple and
minimising current harmonics, copper
exhibited lower losses and ran cooler
as a result. After this, REO optimised
the installation of the choke, using its
sophisticated production tooling to
Preserving position
keymount holes on the VSD, the entire
savings by using aluminium windings on
It’s this attention to detail that sets the
drive can be mounted onto the wall of
the core and copper on the terminals. This
two manufacturers apart from their
a control room. This is an improvement
will eliminate any contact corrosion and
competitors. In the same way that a chain
on the typical setup which involves
benefit from cheaper aluminium prices
is only as good as its weakest link, even
installation into a drive cabinet on the
and better thermal dissipation.
minor component failure can have lasting
production floor, which raises problems of
consequences for both the reputation of
effective thermal management, increased
the drive manufacturer and OEM supplier.
chance of ingress and terminal corrosion.
“If the choke used in our drive failed, the
REO was able to pass these challenges by
in other applications and it can provide
drive would also fail,” continued Glyn.
not only demonstrating its installation
weight and cost benefits We can easily
“Because it’s a high-powered element, the
expertise but also testing capability, using
make prototypes using our 3D printing
choke failing can cause a lot of damage to
its state of the art test laboratory. It was
capability to demonstrate the principle”
the drive. It would almost certainly result
here that various voltage, temperature
in the circuit breaker clearing the fault but
and installation options were performance
causing alarm to the customer if smoke
tested under rigorous conditions before
started coming out of the drive. Although
being sent off for type testing and external
this isn’t in itself very dangerous it causes
regulatory validation.
a lot of embarrassment for us as a drive
manufacturer and we can’t accept this.
Telephone: +44 (0)1588 673411
E-mail: [email protected]
Website: www.reo.co.uk
“We are also looking at the possibility
of providing these chokes using plastic
housings. We have had good results of this
The relentless effort to pursue perfection,
demonstrated by these experts in motor
control, continues to show that greatness
is not achieved by never failing but rather
a continuous process of improvement,
even if it means another 10,000 tries.
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