A range of variable-speed drives (VSD) and electric motors, specifically tailored to the African market, has experienced solid sales figures since its recent launch according to specialised electric motors supplier Zest WEG Group.

Although the company has diversified through various acquisitions, the Zest WEG Group continues to see its motors and drives as a core part of its business operations and strives daily to improve the company’s overall product and service offering,” says Zest WEG Group business development manager David Claassen.

“The CFW11 is the latest generation variable-speed drive designed and manufactured by WEG and can be used in a range of applications, as it is designed to operate either normal or heavy duty loads. It provides increased productivity and an improvement in the quality of the process in which it is used,” says Claassen.

The CFW11 was fully designed and developed by WEG’s in-house research and development team with a specific focus on quality, reliability and simplicity.

The CFW11 has been specifically tailored to suit the African market, not only due to the harsh climatic environment, but also because the power utility supply in Africa is often unstable and voltage fluctuations are common, explains Claassen.

“In fact, some facilities in Africa, where we are active, are not supplied by power utilities at all. They use diesel generators or hydro-generators and the power supply is sometimes less stable than the utilities. So the company has added a direct current (DC) line reactor, which although not unique to WEG products, is superior to standard offerings, as the reactors used are designed with larger inductance levels than usual, between 4 and 6% as opposed to standard reactors of around half those values,” states Claassen, adding that the increased line reactor capacity further reduces the harmonic affect and is better suited to operations with weak or irregular power supply.

The VSD implements two types of space vector control – sensorless and closed-loop. Sensorless vector control permits high torque and quick response in open loop conditions, even at low speeds. The self-tuning function of the VSD automatically matches the vector control to the motor and load used.

“Ongoing development work of the range of VSD’s by WEG using space vector technology as opposed to other methods such as DTC underpins the company’s commitment to advanced technology proven by various technology institutions,” says Claassen.

He points out that in applications involving high inertia loads and short deceleration times, a large amount of energy is returned from the motor to the VSD, adding, that to handle this energy, traditional VSDs have to dissipate the energy as heat in power resistors. Such resistors are usually large and some installation criteria, such as positioning, must be considered owing to their heat dissipation.

“An alternative to the use of braking resistors, the CFW11 possesses a braking method in vector control mode called optimal braking. This innovation delivers a high performance braking torque without requiring a braking resistor,” states Claassen.
WEG invests between 2% and 3% of its global gross yearly turnover on research and development (R&D), Zest WEG marketing manager Jamie Wilson points out.

Claassen adds that the open line of communication between the company and its clients regarding the R&D of specific applications is of major benefit to the organisation as well as its clients.
“Clients are often part of the process where application specific designs are required for optimal solutions, leading to new and improved product offerings,” highlights Claassen.

VSD Applications

“The CFW11 can be used in both simple and sophisticated applications, owing to its range of functions and easy configuration, installation and operation,” says Claassen, adding that the VSD, equipped with the company’s Vectrue inverter technology, assists the drive by providing good performance, precise torque and speed control, and high overload capacity.

The product has several built-in protections, alarms and a safety stop function that complies with the EN 954-1, Category 3 and this is an increasing requirement of the African market.

“The CFW11 features the multi pump control, which permits the drive system to control up to five pumps, so as to keep constant pressure regardless of the flow fluctuations. The system also has an intelligent algorithm control of the pumps provided by means of a user application developed to run on CFW11, which decides when to start or stop each pump based on the system demand. Besides this the VSD also monitors the suction pressure and the tank level,” notes Claassen.

The drive also alternates the pumps according to their operating time, therefore, ensuring uniform wear and tear of motors and pumps.
The CFW11 can be used throughout numerous industries including the mining, chemicals and petrochemicals, ironworks and metallurgy, sugar and alcohol, and industrial building industries.

Synchronous Motors

The WEG synchronous motors introduced by the company to the African market in April last year are being increasingly used in mill applications, says Claassen.

“The application of the synchronous motor in industry in many cases results in considerable, economic and operating advantages because of its operating characteristics,” asserts Claassen.

He explains that one of the advantages of the system includes power factor correction.  Synchronous machines are often used on mills, which are generally considered the highest power consuming machine in a process plant. By controlling the power factor to unity, or even creating a leading power factor, it is possible to substantially correct the overall power factor of the entire plant,” he says.

“In a few years, the power savings could match the amount invested in the motor,” asserts Claassen.

“The motor systems are more efficient in the conversion of electricity to mechanical energy, resulting in greater energy savings, and are designed to operate with high efficiency over a variable speed range that provides a better use of energy for various of loads,” cites Claassen, who notes that synchronous motors are designed with high torque on duty, to ensure that the speed remains constant even during great load variations.

Applications

“Synchronous motors are manufactured specifically to meet the needs of multiple applications owing to their construction features, operation with high performance and adaptability to all types of environments,” says Claassen
The group provides its customers with technical support throughout Africa. These services include 24/7 customer support and on-site services such as start-up and commissioning, diagnosis and repair, for synchronous machines as well as all products offered by the Zest WEG Group including electric motors, VSD’s, switchgear, transformers, motor control centres and generators.

“Our highly trained and experienced team is capable of handling complex challenges in the field and providing remote support using the latest equipment, which produces reliable results,” Claassen highlights.

He is confident that, if the correct installation and maintenance is undertaken the synchronous motor system could last for decades.

Claassen says that the Zest WEG Group continually strives to keep its status as market leader by providing high quality electrical engineering products as well as after sales support and know-how to the entire African market.