Industries

As the industry looks to become more efficient, for example by extending the required maintenance intervals, even the smallest things can make a difference. We have the products and expertise to ensure that problems related to electrical discharges, such as bearing erosion, can be tackled in practice.

Complex machine trains include generators, motors, compressors, expanders, turbines, pumps and gearboxes. Each area has its own requirements for shaft earthing.

High temperatures, corrosive chemicals, confined spaces, oily environments and potentially explosive atmospheres are just some of the challenges Sohre brushes face today.

Sohre brushes are manufactured from the highest quality materials that meet the highest quality standards, enabling them to work in conditions where other earthing brushes would fail.

Together with our customers, we develop solutions that safely master the many challenges of operating earthing brushes, even in potentially explosive atmospheres, and meet the locally applicable safety requirements.

Stray currents in turbo generators can lead to electrical discharges that cause damage to the machine.

• Erosion of bearings, gears and seals.

• Faulty signals from vibrations and temperature sensors.

• In extreme (and rare) cases, they can lead to self-excitation and thus to catastrophic failures.

Electrical discharges can be avoided by earthing shaft currents, although this is by no means a simple procedure. An effective earthing brush must be able to earth low voltage and withstand high voltage at the same time.

• Low voltages can already be damaging, as a potential difference of 0.5 volts can cause damage to gear parts. Earthing such low potentials requires very low resistance and constant contact with the rotating shaft.

• High voltage is not uncommon. Condensing turbines and gas turbines can generate voltage peaks of up to 1000 volts and more.

Sohre grounding brushes can maintain constant, low-resistance contact with the machine shaft, allowing grounding of low-voltage discharges; however, they are also robust enough to dissipate high-voltage discharges.

A variety of generator fault conditions can be detected as a pattern on the generator shaft voltage using an oscilloscope (or monitoring device) attached to a Sohre brush.

• Failure/degradation of bearing insulation can be seen as a drop in shaft voltage near the bearing or as a voltage wave analogous to shaft rotation.
• Ground faults on individual rotors can be seen as a DC offset on the generator shaft.
• Problems with the excitation system filters lead to rapid voltage peaks with a fixed time interval between the peaks.

Sohre earthing brushes have already been installed in thousands of systems and machines in Germany, France, Great Britain, Greece, Italy, Spain and many other countries around the world.

The tension on the propeller shaft (potential difference between shaft and hull) can lead to corrosion on the shaft and the shaft seal. Sohre brushes can minimize the tension on the propeller shaft and reduce corrosion.

Frequency inverters can lead to voltage peaks that damage vulnerable bearings and seals. We have the technical experience to implement solutions to reduce voltage peaks.

Failure of bearing insulation can lead to damage. Sohre earthing brushes can be used to detect and rectify bearing insulation problems.

Like its ground-based counterpart, shipboard power generation can also suffer from the damaging effects of electrical discharges in the shaft. Sohre brushes have been tested in the most demanding environments and offer unrivaled protection against stray electrical currents.