Lenze's SMV frequency inverters are now available with integrated isolators. Suitable for modernising a vast number of drive applications encountered throughout industry, the standalone IP65 inverters can be used anywhere on motors up to 7.5kW with single- and three-phase supplies. Lenze says this represents 70 per cent of the AC motors used in the UK. The addition of a simple isolator without reducing the enclosure class makes the SMV even easier to integrate into existing or new machinery and equipment.
These inverters are one of the easiest ways to convert fixed-speed motors to variable-speed running. Uses include improving comfort levels in ventilation systems, allowing the drive to stop or run at creep speed when there is no demand, and matching speed to the demand from the load - as is often needed with fans and pumps. In all these cases the SMV inverter can simply be fixed to any flat surface near the motor without requiring a panel.
As soon as the inverter is in use, energy costs start falling as the speed reduces. In fact the saving is proportional to the cube of the speed, so a reduction of only 20 per cent can cut electricity bills by 50 per cent. The result is that payback periods of less than one year are commonplace.
Where speed is currently being controlled by means of mechanical variators with belts, chains or planetary designs, these units can readily be replaced by the SMV inverters to deliver energy savings. Mechanical variators work with the motor running continuously at rated speed and their mechanical friction design means efficiency is relatively low. In addition, periodic maintenance and downtime is needed. On the other hand, SMV inverters are maintenance-free, will run at significantly higher efficiency levels (typically saving 10-40 per cent running costs), and will give a broader speed range of up to 50:1, with better speed holding accuracy.
Lenze's SMV drives are modern flux vector controlled frequency inverters with IP65 enclosures to enable operation outside control cabinets. SMV units are available for single-phase supplies up to 2.2kW and three-phase supplies up to 7.5kW, delivering 200 per cent overload for up to 15 seconds. Simple pushbutton control with an LED display is available on the front face. Alternatively, remote control is possible via a potentiometer, digital signals or Ethernet, DeviceNet, Profibus or CANopen fieldbuses.
Another notable feature is the EMV plug-in memory chip that stores all the drive parameters. This is a great aid for series production where drives can be configured off-line, and makes drive replacement simple and quick.
For many motor applications fixed speed is the wrong speed. Single-phase motors can be replaced with a single-phase SMV and a standard three-phase motor to give higher starting torques. The inverter can also act as a soft start combined with variable-speed control. Two-speed motors often deliver two 'wrong' speeds, which is a problem that can readily be solved by installing an SMV inverter. The new combination of IP65 enclosure and isolator makes the SMV adaptable throughout industry.
Follow the link for more information about IP65 SMV frequency inverters.