EDITOR’S CHOICE
VARIABLE SPEED DRIVES
QUANTUM CONTROLS
WHAT ALL ENGINEERS SHOULD KNOW ABOUT
VARIABLE SPEED DRIVE REPAIRS
Largest Load Test Facility in the UK at Quantum’s Repair Centre in Prudhoe
I’m sure we can all agree Variable Speed
Drives are expensive pieces of equipment
that require regular maintenance to minimize
premature failure and maximize the life span
of your asset. Most companies that offer Drive Repair do
not have the required load test facilities and
hence they simply carry out a resistive load
test which actually does not show if the IGBT’s
are fully functioning as a power device.
However, all makes of Drives do fail and one
of the most common faults is IGBT (Insulated-
gate bipolar transistor) failure. An insulated-
gate bipolar transistor is a three-terminal
power semiconductor device primarily used
as an electronic switch in Variable Speed
Drives. This leads to a very high percentage of IGBT
drive repairs simply failing again as soon as
they are fitted to the original application
when load is introduced, leading to another
repair cost and more costly downtime for
your process.
When a drive suffers an IGBT failure the best
practice is to replace all three devices, even
if only one has actually failed, as the fault
condition more often than not weakens the
remaining devices which will inevitably lead
to a further premature failure and more costly
downtime for the user.
So far, I’m sure I’ve not told you anything you
don’t already know, but the real issue with
drive repairs is this…it is imperative that each
repair is fully load tested. This is important
because each IGBT has a free-wheeling diode
which you can only accurately be tested with
a full inductive load test.
8
PECM Issue 41
In summary all engineers should only send
their valuable variable speed drive assets to
drive repair facilities that have fully qualified
Drive Engineers who have attended the
relevant manufacturers courses. But also
insist that the repairer has suitable load test
facilities, that they carry out a full load test
on your drive and they give you the option
to attend a witness test or at the very least
request a video of the final test.
Insisting on these simple steps for all your
drive repairs ensures 100% that your drive is
repaired correctly and fully functioning before
you put back into service on your plant, thus
ensuring minimum repair cost and minimises
expensive lost production costs.
Replaced IGBT Modules must be Load Tested
Quantum Controls have an 8,000 square foot
Drive Repair Facility near Newcastle with full
load testing facilities and are Official Drive
Service Partners for all major Brands of Drives.
When you next have a Drive failure get
in touch with our expert team for repair
estimate.
Kevin Brown, Owner, Quantum Controls
[email protected]
01661 835566
www.quantum-controls.co.uk