Phase Converter help

i would assume that if you are looking at converting 3ph equipment to run in a shop that does not have 3ph power you are likely not going to be using the equipment at a duty cycle that would wear out internals of a VFD in short order.

Similarly, most of the electronics that are not high voltage/current consumption run on 120v in CNC equipment. Most of this kind of equipment has a step down transformer or other device that pulls off a single leg to power those electronics. that part of the equipment could be pretty easily rewired to run of 120v without running thru the RPC/VFD which would remove any issues with power fluctuation.
 
Metto said:
i would assume that if you are looking at converting 3ph equipment to run in a shop that does not have 3ph power you are likely not going to be using the equipment at a duty cycle that would wear out internals of a VFD in short order.

Similarly, most of the electronics that are not high voltage/current consumption run on 120v in CNC equipment. Most of this kind of equipment has a step down transformer or other device that pulls off a single leg to power those electronics. that part of the equipment could be pretty easily rewired to run of 120v without running thru the RPC/VFD which would remove any issues with power fluctuation.
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For me an RPC made sense because I have 6 pieces of 3 phase equipment ranging from 1/2hp to 10hp. I didn't research VFD's because I was under the assumption that they were too expensive and not well suited to my application. In hindsight, I probably would have come to the same conclusion, but I do wish I would have looked into VFD's more.
 
I have been around these runnin pumps and such that we wanted to adjust pressure and flow on through motor frequency/rpm. I have not ever seen one producing a three phase leg. How would VFD make this any different since power flows through the unit to provide two legs and feed the single phase motor which in turn makes the third hot leg? Or at least that's my understanding of the unit. VFD to me just sounds like a slower smoother start up to the same frequency or hertz to get the job done. Only advantage I see may be packaging and the need for less capacitance to start up.
I did check into just going with single phase motor to run it alone. It and the needed start capacitor and a bit of rewiring to get around existing step down transformers cost double the RFC.
And like stated before I can use this for multiple loads and more three phase toys.
VFD to me sounds like a waste of technology since one only needs a single hertz to power a static load or pump that needs only turn a preset RPM.
 
Most VFDs in use today are a 3-phase output. The nice thing about a VFD is adjustability to a finite level. A VFD vs. a motor soft start is like comparing a Miller Diversion to a Dynasty 300. Do they do the same thing? Sort of, if all you're looking to do is stick metal together. VFDs do what they do by taking the incoming AC current, converting it to DC, and then chopping it into whatever waveform and frequency they need via SCRs. Just like an inverter welder. Due to the rectification of the AC incoming, they can take single-phase power and convert it to 3-phase pretty effectively. They were generally passed over in favor of RPCs because for a long time, the rotary was the cheaper option. VFDs have just only recently come down in price to the point that they're readily available and cost-effective for the average consumer. Thank the Chinese for that. Miniturization, surface-mount and multi-layer technology, advances in component tech, and cheap labor have all worked together to bring the size and cost down considerably. Downside: potential for repair in the case of failure has gone down, as has general reliability and ruggedness.
 
catfishblues said:
Most VFDs in use today are a 3-phase output. The nice thing about a VFD is adjustability to a finite level. A VFD vs. a motor soft start is like comparing a Miller Diversion to a Dynasty 300. Do they do the same thing? Sort of, if all you're looking to do is stick metal together. VFDs do what they do by taking the incoming AC current, converting it to DC, and then chopping it into whatever waveform and frequency they need via SCRs. Just like an inverter welder. Due to the rectification of the AC incoming, they can take single-phase power and convert it to 3-phase pretty effectively. They were generally passed over in favor of RPCs because for a long time, the rotary was the cheaper option. VFDs have just only recently come down in price to the point that they're readily available and cost-effective for the average consumer. Thank the Chinese for that. Miniturization, surface-mount and multi-layer technology, advances in component tech, and cheap labor have all worked together to bring the size and cost down considerably. Downside: potential for repair in the case of failure has gone down, as has general reliability and ruggedness.
Click to expand...
thanks good info and in "engrish"
 
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