Over the past five years, the trend towards more energy efficient factories has led drive manufacturers around the world to turn their attention to developing industrial AC motors which operate with fewer components and improved efficiency.
More efficient drives dissipate less heat and hence require smaller heat sinks – traditionally the largest component. Reducing the component count has allowed manufacturers to make use of the integrated circuit techniques common in the electronics industry. Smaller heat sinks and fewer components allow smaller units.
Power and control circuits are now being manufactured in volume, and the price of components has tumbled, making the drives business intensely competitive. And as the electronic content of drives has increased, so several Far Eastern manufacturers not previously associated with the power transmission market have begun to produce variable speed drives, making the market even more competitive.
The result is that as prices have fallen and sales volumes of drive devices have had to rise at a faster rate in order for manufacturers to achieve reasonable growth.
When drives technology was in its infancy a 7.5kW drive was listed at a price of £1,750. Today, a drive of the same power but with much more technical sophistication can be bought for £755 – well under half the price. `The price per kilowatt is coming down at an alarming rate,’ says Eddie Kirk, sales and marketing director of Control Techniques, Britain’s leading drives manufacturer, `but at the same time manufacturing costs are up. Drives technology is now so mature that everyone has it… and it’s dog-eat-dog.’
Development costs involved in reducing the component count are significant and at the same time manufacturers have to comply with regulation such as the Low Voltage and EMC directives. To develop a modern drive with the functionality demanded by today’s market involves an investment of around £2m in the integrated circuit alone. `The total development costs for a mainstream drive can be as much as £5m,’ says Kirk.
The advanced technologies used in drives manufacture naturally have their benefits. Production methods have been greatly improved. Printed circuit boards can now be completed in a single pass with assembly involving only two board components. This cuts testing time and reduces manufacturing costs.
Kirk claims that Control Techniques’ latest offering, the Commander SE, has sold some 30,000 units in the most popular sizes – up to 4kW – since its launch last November.
The drive for size
Across Europe, other leading drives manufacturers have not been slow in following the trend for component reduction and smaller products. The latest offering from Telemecanique,for example, a brand of Schneider Electric, has a footprint 30% smaller than previous models. Its Altivar 28 range, launched last month, offers an extended range of features including EMC protection. Because of its efficient design, the new drive has an optional fully-enclosed version which does not need a heat sink and has a maximum power rating of 4.4kW.
It is becoming more common for drives to incorporate communication features similar to a PC. The Altivar 28 range, for example, includes communications facilities as standard, allowing remote configuration and control.
Other drive manufacturers have incorporated communications technology based on the control equipment industry’s fieldbus protocols. Control Technique’s Commander SE drives, for example, offer the Profibus communications protocol for the food, beverage and process industries, and Devicenet for the automotive sector.
The drives business is becoming a commodity market as most manufacturers produce devices with similar technology. Price is now the main factor differentiating competing brands.
Also, there is a limit to how much smaller drives can be made, and manufacturers are getting close to that limit. The use of more efficient electronics, for example, has developed to the point where cable access and the number of terminations required is now what determines the overall size of the product – and many manufacturers have sacrificed the number of terminals in the search of further compactness.
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