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In power distribution, safety and reliability play a crucial role. This applies to all components in switchgear, but especially to the drive systems for medium- and high-voltage switches. “Reliable motors are essential, especially during events such as short circuits, ground faults, fault currents, or overloads—which can occur in municipal substations or railway systems, among other places—to ensure the switches function properly,” explains Christian Skaletz, project manager at Groschopp. “They also play an important role during maintenance work, as entire sections of the grid often need to be safely de-energized to protect personnel.” In any case, when a switching operation is triggered, the contacts must be separated quickly and precisely—regardless of the external power supply, grid voltage, or environmental conditions. To enable multiple switching operations, an energy storage device is required—often in the form of a mechanically pre-tensioned spring. After the switching operation, the spring is re-tensioned using robust electric motors. Other options for mechanically storing energy include the use of an oil-pressure or plate spring accumulator.

Switchgear manufacturing requires powerful and compact drives that operate with 100% reliability, even if they have not been used for several months and then suddenly have to go into overload operation. “For many decades now, we have been developing custom motors for power distribution that are used in various low-, medium-, and high-voltage applications—that is, across a wide range up to about 200 kV,” explains Skaletz. “This allows triple circuits to be safely implemented, for example, in vacuum circuit breakers, grounding disconnect switches, and tap changers for transformers.”

Rugged and Cost-Effective DC Motors
Groschopp offers commutator motors with enclosures or as panel-mount versions. The manufacturer’s KE series was specifically designed for medium- and high-voltage electrical switchgear, but these motors can also be integrated into consumer products as well as industrial automation systems. These brushed DC motors are characterized by their high quality and long service life. Thanks to their robust construction and repairability, they are ideally suited for use in demanding environments. DC motors in the KE series can be manufactured as series-wound or universal motors with load-dependent speed, as speed-stable shunt motors, and as double-wound motors. 
In switchgear technology, series-wound motors are primarily used in the high- and medium-voltage ranges because they have a simple and fairly compact design, can be heavily overloaded for short periods, and can be operated with both DC and AC current. “As the name suggests, in series-wound motors, the armature and field windings are connected in series,” explains Skaletz. “During startup, the characteristic curves in the stator and rotor rise at the same rate, making them ideal for applications that require high starting torques.”

Adjustable without drive electronics
The series-wound motor also exhibits self-regulating behavior, as its speed depends heavily on the load. In switching mode, these motors can operate at very high speeds with low initial torque—for example, to tension a spring—and as resistance increases, they can reduce their speed again to generate the necessary torque.

“Many electric motors require extensive control systems and are therefore too complex for applications in switchgear,” explains Skaletz. “Our KE motors, on the other hand, do not require external power electronics, making them a cost-effective option in many applications.”

Some of the DC motors in the KE series are also reversible on a single pole, which facilitates easy retrofitting and modifications. Adjustments regarding the flange, shaft, and motor base are also possible. “Our comprehensive drive portfolio for power distribution is characterized by high flexibility and a wide range of customization options,” emphasizes Christian Skaletz. “In addition, we are constantly further developing our commutator motor technology—based on our customers’ needs.”

“When selecting motor technology, it is important to pay close attention to the specific requirements of the application,” says Skaletz. “Ultimately, the customer decides for themselves which drive technology is right for them based on a variety of factors—especially with regard to performance requirements, installation space, and safety considerations.” Groschopp offers comprehensive consulting, assists switch manufacturers in selecting suitable drive solutions, and, if necessary, develops customized solutions that meet individual needs.

The current trend in drive technology is toward particularly compact and powerful permanent magnet motors. They offer several advantages, especially in applications where installation space is limited. Another key development for the future, however, is brushless DC motors (BLDC), which are increasingly being used in modern switchgear due to their maintenance-free operation and superior performance. “To broaden our capabilities in this area and provide our customers with optimal support in the future, we will continue to develop these technologies,” emphasizes Skaletz. “But regardless of which motor technology the customer ultimately chooses: durable, reliable, and high-performance drive technology is a decisive factor for safe and efficient power distribution.” This means that in all areas—whether low, medium, or high voltage—quality always pays off in avoiding costly outages and ensuring the operational safety of the entire switchgear and the associated infrastructure.

Trends in Power Distribution

The current trend in drive technology is toward particularly compact and powerful permanent magnet motors. They offer several advantages, especially in applications where installation space is limited. Another key development for the future, however, is brushless DC motors (BLDC), which are increasingly being used in modern switchgear due to their maintenance-free operation and superior performance. “To broaden our capabilities in this area and provide our customers with optimal support in the future, we will continue to develop these technologies,” emphasizes Skaletz. “But regardless of which motor technology the customer ultimately chooses: durable, reliable, and high-performance drive technology is a decisive factor for safe and efficient power distribution.” This means that in all areas—whether low, medium, or high voltage—quality always pays off in avoiding costly outages and ensuring the operational safety of the entire switchgear as well as the associated infrastructure.

Find out how the experts at Groschopp can successfully support your project as well.

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