GAMBICA launch VSD training

GAMBICA, the association for instrumentation, control and automation, is launching a training course on the vital role of variable speed drives (VSDs) in saving energy, as well as improving manufacturing process control and reducing maintenance costs.

The potential energy savings offered by variable Speed Drives – which provide the means to control the speed of electric motors – are rarely given full recognition. The GAMBICA Variable Speed Drives Group estimate that if VSDs were fitted to all potential energy saving applications in the UK alone, this would lead to an annual reduction of more than 500,000 tonnes of carbon produced.

With this in mind, GAMBICA, with the support of the Energy Efficiency Best Practice Programme, has created a training course aimed at the energy-saving aspects of applying VSDs. The course is unique in that it is intended not only to provide product training, but also to introduce consideration of all elements from power source to driven equipment. With fluid movement and energy saving in mind, the course is limited to centrifugal pump and fan applications; AC Induction low Voltage motors (although other types are generally described); and AC Inverters for general purpose use.

The course is designed to increase general awareness to a reasonable technical level. It is designed to suit the needs of maintenance engineers, sales engineers, sales support engineers, consultants and system designers. Entry requirements consist of a basic level of electrical engineering knowledge, although ONC/C&G level would be an advantage.

Modular correspondence

The course is run in a modular correspondence format and materials are issued quarterly. On receipt of your registration fee – the course is priced at £500+VAT – you will be sent the first two of 11 modules, as follows:

  • Setting the scene (UK energy situation).
  • Motors
  • Assignment 1

  • Speed Control
  • VSD technical overview
  • VSD load characteristics
  • Installation considerations
  • Assignment 2

  • VSDs with pumps
  • Assignment 3

  • VSDs with fans
  • Assignment 4

  • VSD control considerations
  • Financial appraisal and proposals
  • Final project – work-based study
  • A tutor is allocated for each assignment to provide expert advice and support. In addition, you will need to select a mentor – someone local to you whom you respect for their experience and knowledge, to guide you through any problems. The course is expected to cover a period of 150 hours with completion within six months of issue. Deadlines are set for each assignment.

    Check the variables

    In the past, VSDs have largely been employed in the service of production. Now, however, attention is being focused on energy savings. Roy Cooling, WYKO, offers an insight into the rise and rise of the variable speed drive.

    AC frequency converters were introduced in the late 60s/ early 70s, and up until then variable speed requests were generally serviced by offering DC or by various mechanical forms of control.

    Since the introduction of AC frequency converters and technical advances in electronic technology, AC variable speed drives (VSDs) now dominate industry for the vast amount of applications where variable speed is required, generating some £70m worth of business each year.

    Until the introduction of the digital drive in the 1980s, AC drives were quite large units and in some aspects unreliable with accurate forms of control being unattainable due to being analogue driven. The present day digital drive, however, is a compact, user friendly unit able to offer accurate speed control, in most applications equal to DC drive performance.

    In general, there are two categories that all drive applications come under: constant torque, for speed control; and variable torque for energy consumption.

    Where a pump is too big for the job, and it has to be valved back to control the flow, if a variable speed drive is used it will control the flow by reducing the pump’s speed and so reducing the energy used at the same time. This is obviously cheaper than replacing the total pump installation, pipes, valves etc. Conversely, where a pump is correctly sized but the flow varies, the variable speed drive can be used to match the driven speed to the demand, reducing both speed and energy use. bear this in mind: a 10% reduction in speed means a 30% reduction in energy costs.

    The same rule applies to fans. It is common practice to use dampers to reduce air flow, so the motors are run flat out, but pushing air down a semi-blocked pipe. Greater savings can be made by using variable speed drives in the control of a fan. Here, a 20% reduction in airflow means a 50% reduction in energy costs.

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