High quality and flexibility: The BMR frequency converter SFU 0303

BMR, a specialist in static frequency converters for motor spindles, presents the SFU 0303, a flexible continuous-duty converter with 3.8 kVA at 230V mains voltage for driving asynchronous and synchronous spindles.

Technological change can be clearly demonstrated in the field of electronics. Frequency converters are modern, high-tech devices adapted to the requirements of Industry 4.0 that control a wide variety of motors. The challenges are manifold; they include optimal voltage regulation, stable speeds, the best possible device cooling under extreme loads, and much more. Maximum precision is required here to ensure that the machines can operate efficiently and trouble-free for as long as possible.

“Every application is different. That's what makes the work so interesting. Our aim is to always provide customers with the best possible device for their specific requirements on site,” says Stephan Brittling, Managing Director of BMR elektrischer und elektronischer Gerätebau GmbH (BMR for short), based in Schwabach.

The milestone in the more than 45-year history of the internationally successful family-owned company was the development and manufacture of frequency converters in 1990. The new product line benefited from the company founder's many years of experience in electronics manufacturing and expanded rapidly. Today, BMR is the market leader for modular converters with control systems ranging from 80 VA to 1,000 VA with the smallest possible mounting area.

These formats are ideal for use in small to medium-sized milling and grinding machines, as well as for all CAD/CAM systems with high-speed drives,“ explains Stephan Brittling. ”At the same time, we are one of the few manufacturers to offer frequency converters as tabletop devices."

And the product portfolio continues to grow. The high-quality devices in various sizes and performance classes form a modular system and are always interchangeable with all previous models. The performance spectrum includes static frequency converters for motor spindles in the power range from 150 VA to 3.8 kVA for high-voltage and low-voltage types. In addition, there are smart industry products such as the Motorview process visualization system.

One of BMR's trademarks is its tailor-made complete packages: “With us, there is no need to buy anything extra. From the connection terminals to the brake chopper to the mounting plate for the small converters, everything is included. There are no hidden costs,” says Stephan Brittling. “And on top of that, we offer free support.”

Always at the cutting edge of technology

The SFU 0303 was designed in 2009 specifically for use in modern machining centers. With a rated power of 3.8 kVA at 230 V mains voltage, it achieves speeds of up to 240,000 rpm. The great strength of the device: across all power ranges, the DC link always provides exactly the voltage required for the necessary load and speed. This ensures high-precision adaptation to the respective application, which both improves the running characteristics of the spindle and reduces its heating. In most cases, this completely eliminates the need for additional components such as sine filters or output chokes. For the operation of asynchronous and synchronous spindles, 16 parameter sets can be stored and selected on the display or via the PC software.

Over the years, the drive specialists in Schwabach have continuously optimized the converter and developed a wide variety of designs. In addition to six digital and two analog inputs, users also have six relays and two analog outputs at their disposal for free configuration. The integration of sensor inputs for rotary encoders and temperature monitoring (PTC, KTY, PT1000) further improves the control and monitoring of the system. The advantage of the control cabinet housing design is that the external heat sink makes the housing chip-proof and protects it from contamination. Cooling and heat dissipation are provided by a temperature-controlled fan. The devices meet all safety requirements, from automatic spindle braking in the event of a power failure during operation, to controlled braking to a standstill in the event of overheating of the spindle or converter, to safe pulse blocking in accordance with EN 954-1 K3 and Safe Torque Off (STO).

Sustainability

Today, the SFU 0303 in its various versions is one of the company's top sellers. For over 20 years, Schaeffler has been one of its customers, using this particularly reliable and powerful key component for dressing grinding wheels in its branches worldwide.

While the “inner workings” of the converter are always kept up to date with the latest technology by the development department, the dimensions and connections have remained the same. This allows customers to use the latest device without having to make any changes to the installation and handling. Retrofit saves costs.

"With our 1:1 interchangeable replacement devices SFU 0303/2 and SFU 0303/4, we are bringing our customers' existing grinding and milling centers up to the latest standard. The many configuration options make it easy to replace the old devices of the SFU 0401 and SFU 0302 series,“ explains Managing Director Susanne Brittling, who runs the innovative company with her son Stephan Brittling. ”The latest version also includes Safe Torque Off, although the version with safety shutdown via pulse blocking is still available."

Special mounting brackets are used to replicate the original hole pattern, allowing the converter to be installed directly without any reworking. On request, it can also be supplied as a plug-and-play device, which minimizes machine downtime and further helps to save costs.

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