Alternatives To Rotary Converters
Alternatives exist to rotary phase converters for operation of three-phase equipment on a single-phase power supply.
- Static phase converters are actually not a converter at all. They start the motor spinning and then "single-phase" the motor. They also require de-rating of the motor being run, typically to 60% or less of its three-phase rating. A 10 hp (7.5 kW) motor can be run only at 6 hp (4.5 kW). The power balance and thus motor efficiency is extremely poor. Failure to run a motor at reduced load will result in overheating and quite often destruction of the motor. Many machine manufacturers and dealers specifically state that the use of a static converter will render any warranty null and void.
- Three phase inverters and related variable frequency drives, may, under certain circumstances, produce large amounts of harmonic distortion in their output, and the efficiency of the inverter-motor combination can be poor. When poor efficiency in a VFD powered motor has been investigated, in every case documented to date, the root cause for the loss in efficiency was either improper installation or a failure to adhere to best practices. Almost universally, a VFD increases the efficiency of a system and reduces operating costs.
- Inverter drives (VFDs)can damage some motors not rated for use with an inverter but this is not a concern when motor voltages are less than 440 VAC. Motor manufacturers may void warranties on non-inverter rated motors if they are run at a variable speed or with an inverter, but most three phase motors over 10 hp (7.5 kW) sold today are rated for use with an inverter drive. This damage can be prevented by the use of load and line reactors or in Europe a DU/DT filter. This reactor or filter reduces the voltage stack up that can occur on older high impedance motors such as wound rotor motors. The filter prevents the windings of the motor form insulation breakdown caused by voltage stack up.
- VFDs that have a capacity greater than 3 hp can be costly thus making the RPC an attractive option.
Read more about this topic: Rotary Phase Converter
Famous quotes containing the words alternatives to and/or alternatives:
“The literal alternatives to [abortion] are suicide, motherhood, and, some would add, madness. Consequently, there is some confusion, discomfort, and cynicism greeting efforts to “find” or “emphasize” or “identify” alternatives to abortion.”
—Connie J. Downey (b. 1934)
“Clearly, society has a tremendous stake in insisting on a woman’s natural fitness for the career of mother: the alternatives are all too expensive.”
—Ann Oakley (b. 1944)