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(8th October 2010)
The latest active front-end (AFE) drive technology is fast becoming the industry standard for manufacturers, owing to its energy savings, a near unity power factor and a total harmonic distortion of current (THDi) of 5% of nominal current at full load, low-voltage components sup-
plier CHI Control Components, a division of Actom, drives product manager Derek Sleep tells Mining Weekly.
The AFE drive is a bidirectional power converter for the front end of a drive system, which provides the option of speeding up and slowing down the motor and, if the motor is not running under full load, the voltage can be limited further, which can save energy.
Unlike standard drives, an AFE drive is identified where the rectifier has been replaced by an insulated gate bipolar transistor, which is used to create the dc bus, he says.
The AFE drive can be used as a regenerative drive system so that, should braking be needed
for the motor, when, perhaps, lowering a hoist, energy will not be released through a braking
resistor but will regenerate back onto the system, improving the efficiency.
Sleep says that the power factor of the AFE drive is almost unity, which means that the reactive power taken from the system is almost zero, resulting in fewer power losses.
A standard drive without filters creates about 80% THDi, and drives using filtering mechanisms and other options, such as 12-pulse rectifiers, create
between 40% to 15% THDi.
The AFE drive creates less than 5% THDi.
Total harmonic
distortion returned to the system can cause damage to the surrounding parts and equipment by heating up conductors and
motors, as well as affecting bearings on the motors.
The operation of communication devices and computers can be affected and damaged, he says.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| NQ202823 KOYO | 28 | 23 | |
| NQ20/20 KOYO | 28 | 20 |