These are standards published by the U.S. Department of Energy to help industries to make better decisions in their use of motor controllers…

U.S. Department of Energy

When Should Inverter-Duty Motors Be Specified?

Incorrect application of AC Inverters also known as VFD’s (Variable Frequency Drives) can cause bad effects within the motor. The VFD Industry manufacturers and suppliers have been promoting that a VFD can be fitted onto any 3 phase induction motor and this has been accepted as a true fact. This is however not correct as can be seen by this US Department of Energy Tip Sheet #14.

The effects of the high switching pulses used to create a modulating pattern which in turn produces an assimilated sinusoidal current wave form cannot be converted into rotational energy by many motor. But there are motors specifically designed to use and produce these pulses to produce full output torque across the speed range of the motor.

With the correct VFD, application and installation and motor selection potential damage can be avoided. The Invertec line of VFD’s used and sold by SID-TEC are well advanced and have a pulse width minimum lockout, this is determined when the VFD is run in the Open or Closed Loop Vector mode and is detected set for the motor connected during an Auto Tune function.

U.S. Department of Energy

Minimize Adverse Motor and Adjustable Speed Drive Interactions

The VFD (Variable Frequency Drive) Industry has been erroneously leading people to believe that there is no thought necessary for the application and installation of a VFD. Anyone who has argued with this has been accused of simply not having a good VFD. This is not the case, as can be read in this US Department of Energy Tip Sheet #15.

Cable length affects the transmission of the high speed pulses of energy, the type of cable also has a large effect on the amount of potential damaging voltage spikes. Adding a reactor and using multi stranded small sectional diameter conductors within the wire or cable of appropriate size, along with the correct motor and the shortest possible cable length will help and provide a sound reliable installation.

With the correct VFD, application and installation potential damage can be avoided. The Invertec line of VFD’s used and sold by SID-TEC are well advanced and have a pulse width minimum lockout, this is determined when the VFD is run in the Open or Closed Loop Vector mode and is detected set for the motor connected during an Auto Tune function.

U.S. Department of Energy

Is it Cost-Effective to Replace Old Eddy-Current Drives?

The costs of operating motor functions or manufacturing a product are always something that has to be evaluated. Throwing money away on an outdated piece of equipment by paying outrageous energy bills is not a good practice.

Fans and Pump application other than positive displacement unit should never be connected to an Eddy-Current Drive. With the VFD you will only pay for the energy you consume plus 3% for powering the VFD and some losses, while with the Eddy-Current drive you pay full price by the Horse Power. There are special VFD’s designed especially for Fan and Pump applications.

There are many different application requirements in the Industrial and production world, from the low torque requirements of both fan and pump to the ultra-harsh torque requirements of crushers, conveyor belts and punch presses. Most of the shock loading machines such as punch presses and crushers have a fly-wheel which stores the energy and absorbs the mechanical energy shock created.

There are VFD and motor combinations which will produce the correct amount of output torque for most of today’s applications, and they do provide energy cost savings, but they are not the answer to every application and do have some drawbacks. The DC drive also has a good output torque at a cost effective ratio but is shunned because of the brushes and higher maintenance. Soft starters are also an option for applications where full speed of the motor is required constantly, but there is a poor energy saving based on consumed energy between full load and no load conditions.