Inverters feature integrated isolator

The SMV range of frequency inverters from Lenze is now available with an integrated isolator.

The standalone drive has an IP65 enclosure and can be used anywhere on motors up to 7.5kW with one- and three-phase supplies.

The addition of an isolator without reducing the enclosure class makes the SMV easier to integrate into machine concepts, the company said.

The inverters are an easy way 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 be fixed to any flat surface near the motor without requiring a panel.

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 a year are commonplace.

Mechanical variators that use belt, chain or planetary designs can readily be replaced by the SMV inverters.

Such 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.

The SMV inverters are maintenance free, will run at higher efficiency levels typically saving 10-40 per cent running costs, and will give a broader speed range up to 50:1 with better speed holding accuracy.

The Lenze SMV is a range of modern flux-vector-controlled frequency inverters designed with IP65 enclosure to operate outside control cabinets.

It is available for one-phase supplies up to 2.2kW and three-phase up to 7.5kW delivering 200 per cent overload up to 15s.

Simple pushbutton control with a LED display is available on the front face.

Alternatively, remote control is possible via a potentiometer, digital signals or fieldbuses Ethernet, Devicenet, Profibus and Canopen.

Another feature is the EMV plug-in memory chip that stores all the drive parameters.

This is a good aid for series production where drives can be set up off-line, and makes drive replacement simple.

For many motor applications fixed speed is the wrong speed.

Single-phase motors can be replaced with a one-phase SMV and a standard three-phase motor, giving higher starting torques.

The inverter can act as a soft start combined with variable speed control.

Two-speed motors often deliver two wrong speeds, which can readily be solved by the SMV.

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