An extensive low voltage AC
drive refurbishment
programme has been carried
out by ABB on a series of drives used
at UPM Shotton Paper’s recycled
fibre plant (RCF). The RCF is a
critical process, feeding the paper
machines which produce more than
500,000t of newsprint per year.

To improve the performance of its
installed drives base, cut downtime
and lower the cost of repairs, UPM
initiated a Focus Improvement Team
tasked with identifying reasons for
downtime on low voltage AC drives.

ABB was invited to join the team.

It was found that the ABB drives
were suffering from dry solder joints
on the power semiconductor units.

Although natural degradation and a
common occurrence with drives, it
was happening outside normal
warranty. However, ABB offered to
support UPM with replacement units.

Using ABB’s service workshop at
St. Neots, the refurbishment, phased
in over six months, included replacing
power semiconductor modules and
fans in 36 drives (from 160 to 560kW).

Any components identified as faulty
were replaced after agreement with
UPM Shotton.Up to four drives at a
time were refurbished during shorttime
shutdowns at the plant. Two
standby drives were supplied to cover
those being refurbished.