MLT Drives (MLT) is a small Cape-based company with a staff of some 25 employees. It was established during 1986 with its focus on the design, manufacturing and marketing of advanced power electronic products, these including inverters, battery chargers and alternative energy solutions (eg wind and solar). Despite its size MLT has been involved in some major projects, a few of which are reviewed below.
During 2004 the company was involved in the Lucingweni rural electrification project which was a pilot renewable energy exercise commissioned by the National Energy Regulator. The village of Lucingweni had some 220 houses to which energy had to be supplied and to meet this need some 51 kW of PV solar panels and six wind turbines (6 kW each) were installed. The battery bank required had a capacity of some 1,8 million Wh at 220 V d.c. While the developers had intended to use an international company to provide battery chargers and inverters, they were let down and requested MLT to support them. The company provided four MLT SunDrive 14 kW solar battery chargers and one MLT PowerDrive 125 kVA 3-phase inverter. It delivered these in six weeks, allowing the project to remain on schedule with the lights being turned on in the village in October 2004.
Besides working with the NER, MLT also works closely with Eskom in terms of its rural electrification project and has supplied more than 1000 specialised 800 VA inverters for use in Eskom's rural school electrification programme. MLT also developed a 150 kVA three-phase load balancer for Eskom.
In terms of its export programme, MLT successfully developed a 3000 VA train application inverter which converts DC power from the existing railway line supply and converts it to 220 V a.c. for use in the passenger coaches. A single 3000 VA unit is adequate for all the coaches in a train set. Despite strong competition from America and Europe, MLT won a contract in Syria which saw delivery of 200 of these train inverters. In Thailand, MLT was responsible for the development and installation of three solar UPS systems to support the existing grid. At two sites, identical installations saw the installation of eight 7 kVA inverters, only three being used at one time to supply the grid with 21 kVA. At the third site, which was not connected to the grid, two 3,5 kVA inverters supply power to light some 70 households.
At the same time, MLT remains at the forefront of technology used with other renewable energy sources; specially-developed inverters were supplied to the UK for use in their fuel cell development projects. MLT was commissioned by a large telecommunications company in Italy to provide specialised 800 W inverters. These units were developed using the company's existing 800 VA board, and were packaged in 19-inch racks as required by the customer. These units provide secure power to highly-sensitive telecoms equipment.
Besides developing specialised application equipment, MLT offers a full range of standard products. In terms of inverters, a full range of pure sine wave devices are offered including the Mini, the Micro, the Midi and the Maxi. Rated power of this range is from 300 W up to 3 kW with the Midi. The Maxi range has six products ranging from 6 kVA up to 16 kVA. This product range encompasses the current needs of the market from recreational (yachts, caravans etc) right through industrial applications. The other inverter range offered by MLT is its Gridtie products, which, as the name suggests, are designed to inject clean power into a grid. Rated powers are from 2,5 kVA to 10 kVA with sine wave output (less than 5% harmonic distortion) and high efficiency, while being effectively maintenance-free. MLT has an installed base of more than 15 000 inverters located worldwide.
In terms of battery chargers, the company supplies a full range of industrial and heavy-duty products. Chargers are available for both single phase (12 to 48 V) and three phase (36 to 110 V) mains supplies. Its new Millennium 3 charger uses advanced digital signal processing and charges batteries at close to unity power factor. This charger offers some advanced features such as remote access over the Internet, temperature control measurement, and programmable delay start.
Other products from MLT include the Powerstore, which is designed to monitor a battery, measuring currents flowing in and out, as well as the battery voltage. From these measurements, the Powerstore can calculate the maximum Ah capacity of the battery, current percentage charge, total energy consumption and power in and out of the battery. Finally, the company offers its maximum power Point tracking (MPPT) solar regulators as part of its ongoing renewable energy developments. The MPPT is an electronic system that maximises the power flow from solar panels at all times. It does this by continuous monitoring of the power flow, adjusting the voltage and current from the solar panel in order to obtain maximum power flow and thus maximising the potential of the panels.
Within South Africa, MLT offers on-site maintenance and repair. In terms of overseas sales, it has distributors in many countries including Germany, Italy, Syria, Australia, France, Thailand and India. The company was recently certified by Dekra to ISO 9001:2000, a decision taken to satisfy the need for a quality management system that would be recognised internationally.
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