Top ten inverter application tips

1. Soft start
Soft starting of any application protects the mechanical drive system reducing wear and tear on bearings, belts, etc. Soft starting also reduces direct on line starting currents from 600% to 100 -150% of motor rated current.

2. Motor-drive selection
The number one problem experienced by inexperienced drive users is matching the motor and drive voltage; ensure that the motor terminal box connection (star or delta) corresponds with the drive voltage.

3. Low speed motor operation
When an application requires a motor to run for long periods of time at low speeds, typically less than 1/3 base speed, and particularly when additional boost is applied, the motor should be force cooled.

4. EMC
Good cable management is the key to solving EMC problems. Always use screened cable between the drive and the motor and keep control and power cabling separated by at least 100mm. Where control and power cables must cross, ensure that they do so at 90°.

5. Generators
Soft starting is key in reducing generator costs as a system can be dimensioned for continuous rather than start-up operation (4-6 times reduction). A contactor should be placed between the generator and the drive, which should be activated by the Optidrive’s drive healthy output relay. Thus, in the event of a generator over-voltage, the drive will trip causing the contactor to open removing the potentially harmful over-voltage from the drive.

6. Freewheeling Fans
For Optidrive E, use dc injection braking on enable to bring free-wheeling fans to rest before starting to control. Starting a drive into a free-wheeling motor creates a direct short-circuit, which damages the drive and the motor.

7. Variable torque (radial & axial fans)
Variable torque mode can be used to drive radial fans and pumps. Axial/ centrifugal fans or displacement pumps should be driven in constant torque mode (ie heavy duty/150% overload).

8. Single phase supplies
Optidrive offers high power single phase input, three
phase output operation up to 45kW.

9. Energy Saving
In general, reducing the speed of a process will save energy. Using PI/ feedback control, energy saving can be maximised by running a motor at its optimum speed for a particular situation.

10. Variable feedrate
It is often useful to run a particular process at optimum power/ load ie a wood-saw. A first Optidrive can be used to drive the primary process and a second Optidrive can be used to control the feed of the work piece into the primary process. A PI controller uses the load output from the primary Optidrive as the feedback parameter and then changes the speed of the feed drive to keep the primary process at optimum load.

For further information, or to enquire about inverters please contact your nearest branch