Variable Speed DrivesOne of the most effective energy saving tools
While some machinery needs to run a fixed speed within a production environment, many motor applications, fans and pumps have different processes which allows them to run at different speeds. This is where a Variable Speed Drive (VSD) is beneficial in energy efficiency (also known as Adjustable Speed Drives (ASDs), frequency converters, drives or inverters).
What do Variable Speed Drive's do?
VSDs convert the incoming electrical supply of fixed frequency and voltage into a variable frequency and voltage output to the motor, with a corresponding change in speed and torque. Most are controlled automatically.
Typically, using a VSD to slow a pump motor or fan by 20% can make an energy saving of around 50%. By running at a slower speed, the electricity used to match this new requirement is significantly reduced.
Variable speed drives come in various designs and can be used to control a fan or pump. Smaller VSDs (under 15kW) can be standalone devices installed between the electrical mains supply and the motor unit. Advanced versions which operate with several MW of power are used for more precise speeds and torque control. They can also be connected to several control functions and linked to a computer network to provide useful, up-to-the-minute operating data.
Although VSDs are most commonly installed to assist in energy consumption and cost-saving exercises, there are several other benefits:
- More precise control of speed, pressure, flow and temperature
- Prolonged equipment life from soft starting and programmed acceleration or deceleration
- More control at high speed – and in some cases higher achievable speeds
- The possibility of linking with other process control systems
- Recovering electrical energy from braking for reuse
How can AES help with Variable Speed Drives?
AES can undertake a site assessment and evaluate those areas where potential energy reduction and cost savings could be achieved through VSDs, along with an estimated payback period for the recommended works.
The most commonly used VSDs are those applied to AC induction motors. The process of installing VSDs comprises of:
- A rectifier to change AC current to DC current
- An intermediate circuit to condition the rectified DC supply
- An inverter to convert the DC back to an AC supply of variable frequency and voltage
- Control unit to monitor the system and respond to external signals to ensure that the correct output is delivered
AES will work with you to arrange a convenient installation time to minimise the disruption to your business. Your own staff should also be trained to operate the VSD, and we can assist with this.
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