ABB REVIEW 16 DECEMBER 2009

ABB in Ludvika conducts annual gas

analyses of all transformers at Ovako

Bar in Smedjebacken. This past sum-

mer, the gas analysis of the smelting

plant’s 130/20 kV transformer yielded an un-

expected result: it warned of a pending break-

down due to overheating. A breakdown, which

would have stopped the arc furnaces in the

smelting plant, resulting in major losses.

“When ABB’s department for transformer

service in Ludvika notified us of this, we con-

sidered sending the transformer to ABB in

Drammen for repair,” says Reijo Innanen, Elec-

trical Manager at Ovako Bar. “But ABB’s Ken-

neth Gustavsson and Markus Pettersson came

to us instead.”

Breakdown warningThis past summer, ABB conducted a gas analysis of the oil in one of Ovako Bar’s transformers – the analysis showed that a breakdown was imminent.

“Thanks to the warning, we were able to save the transformer with repairs and avoided a loss of pro-duction,” says Reijo Innanen, Electrical Manager at Ovako Bar.

TexT: C-G HanberG PHoTo: Henrik Hansson

a thorough gas analysis may be the salvation of a transformer with problems.

Reijo Innanen at Ovako Bar recognizes the value of annual gas analyses of transformers.“They can prevent expensive production stops,” he says.

An initial ocular inspection showed that

the transformer’s tap changer had most likely

broken down. The transformer was therefore

taken out of operation for a closer look at the

tap changer.

SeRvIce Team On The wayAfter a thorough analysis, ABB’s personnel was

able to confirm that the tap changer had un-

fortunately broken down entirely. The service

team from ABB in Ludvika arrived that same

afternoon and had restored the tap changer to

original condition after two days. Including the

extensive surrounding work, it took a week in

total before the transformer could be recom-

missioned.

“Fortunately, everything largely coincided

with a planned shutdown,” says Reijo Innanen.

“So production downtime was limited to one

shift.”

“If we had been forced to take the transform-

er out of operation at full production, ABB’s fast

efforts on site would have been extremely valu-

able. The fact that we avoided disassembling

and transporting the transformer to Drammen

surely saved around two weeks.

“We also recognize the value of the annual

gas analyses we do on all of our transformers.

They can save big money. We may sign a com-

prehensive service agreement with ABB and

may even invest in a back-up for the step-down

transformer that nearly broke down this past

summer.”

many yeaRS Of TRuSTOvako has cooperated with ABB for many years.

“We have a great deal of faith in ABB’s know-

how, which also includes our processes, and

we also appreciate ABB’s customer-oriented at-

titude,” emphasizes Reijo Innanen.

Markus Pettersson, Project Manager at Instal-

lation and Service at ABB in Ludvika, explains

that gases always develop in a transformer dur-

ing operation.

“The gases are normally dissolved in the

oil and ventilated out through the drying ap-

paratus. In potential faults, gas production in-

creases, however. With regularly scheduled gas

analyses, faults can be discovered early and we

can recommend measures that can prevent a

breakdown.”

OvakO BaR

Ovako Bar in Smedjebacken is a part of the Ovako Group, which manufactures high-quality special steel in the form of bars, wire, pipes and rings.

The steel products are used in the ball- bearing industry, auto industry and engi-neering industry.

The group has a total of 4,000 employees.

“

”

With regularly scheduled gas analyses, faults can be discovered early and we can recommend measures that can prevent a breakdown.

ABB REVIEW 17 DECEMBER 2009

A broken lead-through to a transformer in Stor-norrfors Power Plant could have caused a loss of millions for its owner Vattenfall. A rapid re-sponse by Vattenfall Service and ABB limited the shutdown to just three weeks.

Fast action saved millions

In the middle of the spring flood, a lead-through broke in a trans-

former in the Stornorrfors Power Plant in Västerbotten. Vattenfall

feared that two aggregates had to be decommissioned for several

months at a time when every day of downtime means nearly SEK 2

million in lost revenues.

But Vattenfall Service and ABB saw to it that the shutdown was sig-

nificantly shorter.

“Personnel from ABB in Ludvika were already on-site within 24 hours

and could confirm that a lead-through had probably broken down,” ex-

plains Patrik Stenlund, Project Manager at Vattenfall Hydropower.

The lead-throughs were then disassembled in the 200 ton heavy and

six meter high transformer and transported to ABB in Ludvika.

After a weekend in the test room, ABB knew for certain that the lead-

through had broken down. A new lead-through was manufactured in

all haste and tested before being mounted on the transformer in Stor-

norrfors. Moreover, 55,000 liters of transformer oil was cleaned.

“I mobilized all available personnel by contacting various depart-

ments at ABB,” says Lars Timonen, Proj-

ect Manager at the ABB Transformers

unit. “Everyone did their part whole

heartedly and, consequently, we were

done two weeks earlier than planned.”

“ABB’s effort was commendable and

shows what resources they have,” says

Patrik Stenlund. “In just ten days, the

new lead-through was mounted and

barely two weeks later, we were able to

recommission the aggregate.”

STORnORRfORS

Stornorrfors Power Plant in the Umeälven River is one of Sweden’s largest hydro-electric power plants with four turbines totaling 591 MW and an average annual produc-tion of 2,298 GWh.

Stornorrfors is owned by Vattenfall.

Thanks to fast action, the two rear aggregates at Stornorr-fors were able to be put back into service slightly more than three weeks after the trans-former breakdown.

TexT: C-G HanberG PHoTo: VaTTenfall