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Repairing motors for companies in the petrochemical industry

By working successfully as a team, BENNING reduced production downtime by several months.

Every year, German companies invest 2–4% of their original capital costs in maintaining their production plant. This investment pays for itself, as any downtime can have serious consequences for an industrial plant. Even short stoppages cost a company time and money, can damage their reputation, and also cause customers to feel dissatisfied and lose confidence in them.

One worst-case scenario occurred at a petrochemical company in the Ruhr region in early 2016, when a faulty winding in an ageing motor shut a high-pressure reciprocating compressor down and resulted in the whole production plant completely closing down.

Aiming to keep financial losses as low as possible, the company decided against rebuilding, which could have taken around a year due to the unique design of the defective motor. Instead, they hoped to find a company to repair it quickly; but looking for the right partner proved to be anything but simple, as the motor’s age and specific characteristics required special expert knowledge.

Low speed, high torque

This highly robust 12-tonne motor, measuring 3500 x 3000 x 2200 mm (length x width x height) was made by AEG for use in petrochemicals in 1972. Its combination of relatively low speed and very high torque, which is atypical of motors today, was uncommon and its like had not been made for many years.

Additionally, the motor’s explosion-proof design meant that its windings were subject to special limits, which were officially certified at the manufacturing plant. Designed for maximum safety and efficiency, there are very few companies capable of successfully producing a motor to this specification.

AEG, the original manufacturer, ceased production in 1996 but a company based in the same chemical park reported that it had been working successfully with BENNING for over ten years.

Time factor decisive

As soon as BENNING was contacted, it was clear that time was key. After extensive negotiations in which special bonuses were promised for getting the motor up and running quickly, BENNING agreed to deliver in three months: a time span that was very tight for a project like this, but which BENNING achieved by deploying several of its electrical
machinery employees. Transferring the motor undamaged from the petrochemical company to BENNING was a challenge as the carrier truck required a special device to secure the load. Once the motor reached BENNING’s works in Bocholt, the protective switchgear cover, pipes and steel supports were removed carefully to avoid damaging them.

Over 1000 working hours

The repairs turned out to involve considerably more working hours than if repairing a standard motor. BENNING worked non-stop over six weekends and spent over 1000 hours on the job, working continuously in two – sometimes three – shifts making coils, winding and assembly. Day in, day out, using today's materials and without compromising on quality, BENNING had to recreate the old solutions and elements that the motor used. Flat copper wire was made specially, for example, as it’s no longer readily available in this form. The repair work was made even more difficult as there was no motor documentation.

This is normally produced when making a motor and is used to record relevant details of how it works and what it can do, so that any future work can be done more quickly and easily. Instead, BENNING had to produce new, detailed documentation through reverse engineering, as it took the motor apart and recorded a range of electrical and mechanical measurements and recalculated all the winding data. The documentation also included precisely reviewing the air-gap monitoring winding: this is a device that monitors the air gap between stator and rotor. If the gap is irregular, which could damage the
bearings if it changes its alignment, for example, then an alarm would be raised. Again, BENNING had to remake this winding from scratch and check the data involved by way of calculation to ensure it was feasible first.

Successful teamwork

BENNING`s client sent a quality acceptance engineer to the work of BENNING at regular points to see how the repairs were progressing and record them on-site, so he was always able to verify that BENNING was on schedule at all times. The repairs and installing the motor went smoothly, so not only did BENNING keep to the dates agreed on commissioning, it also managed to bring forward the full implementation to the start of July – originally planned for mid-July 2016.

Proof of the client’s satisfaction was apparent as this project led to a follow-up order. Using BENNING’s preventive service, BENNING now ensures downtimes of any kind can be detected and avoided in good time: a major contributor to ensuring that the operating processes run continuously in future – significantly minimising downtimes and risks.

Further Information

author/contact: Matthias Loerwink
telephone: +49 2871 93 318

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