Quick payback claim for inverter
Original article date: October 1999
We heard about an intriguing terminal box inverter that does not have to be mounted on the motor. Tommy Miller investigated further
Simplatroll believes that a typical application of the Lenze 8200 Motec terminal box inverter will have a payback period of under two years. There are several compelling reasons why this should be the case, in addition to the fact that an inverter will usually save energy costs if the motor speed requirement is not constant.
For an inverter that is mounted on or near a motor, rather than in a control cabinet, there can be an initial saving due to the reduction in cabinet space required. Then, because of the relatively high cost of shielded motor cables, there is another saving in hardware costs. Other savings result from the use of standard motor starter contactors (no chokes required) and local safety isolators (no electrolytic DC bus capacitors required).
There will be occasions where it is not desirable to mount the inverter directly on the motor, perhaps because of space restrictions. Nevertheless, the advantages of an inverter close to the motor are still attractive. Lenze has tackled this dilemma by supplying 8200 Motec inverters separately from the motors such that they can be wall-mounted if you prefer. The design of the heatsink means that the inverter will operate reliably in ambient temperatures as high as 60degC, with no need for forced airflow.
Lenze has spent a great deal of effort designing these new inverters to be high performance products. For instance, with a speed range of 1:50, the units are capable of driving a motor at its full rated torque as low as 1Hz. Speed control is achieved by means of sensorless vector technology.
Three-phase models are available in powers ratings from 0.55 to 2.2kW, but higher power versions are likely to be introduced soon, and single-phase models are also understood to be under consideration.
A few other features and options are also worth mentioning: first, an optional on/off switch and potentiometer can be fitted to the base of the Motec unit; second, there is an integrated PID function for process control; third, a built-in braking transistor removes the requirement for a separate brake chopper. Simplatroll can supply standalone Motec inverters, inverter motors and inverter gearmotors.
- Simplatroll
October 1999