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DPS (Digital Phase Shifter) on Amazon

crickets

Member
Folks,

Has anyone tried those DPS units found on Amazon ? There is a whole lineup of them with different current ratings, and the reviews are solidly divided between the people who are happy with them, and people who fried some motors, typically 3:1. Makes me wonder if the deal is those work with only certain types of motors, but it's not clear what the difference would be.
 

rbcmetalwork

New member
I installed one for a 10hp air compressor. It works fine. The manufacturer in Korea was very helpful with questions I had. I wanted to make sure that I purchased the correct unit for my application. A little bit of a language barrier in the emails but it all worked out.
 

Clive603

Active member
Hard to tell what these things are.

They could be:-

1) stripped down VFD box configured for simple installation and direct control as a replacement for an old style contactor switch. Basically same sort of thing as the Eaton DE1 series VFD boxes which work very well in their intended niche.

or

2) a proper 3 phase output static converter with run capacitors to give a close approximation of all three phases when running and an automatically switched boost capacitor to get things started. I used to build those things when folk asked nicely and they can work pretty well but capacitor tuning is an issue. Falling VFD priced made it uneconomical for me around 10 or 12 years back.

Price is about right for a basic fixed frequency import VFD of so-so "home shop" quality i.e cheaped out a bit on components so things like capacitors, will start going pop after a year or so run time. Hopeless for business but under some weekends and evenings use by Home Shop Harry its gonna be a few years before it dies.

Expensive for Far East production of the sort of things I used to build. Possibly a bit more sophistication on the phase balancing side. Perhaps inductors involved or perhaps some sort of on the fly capacitor bank size adjustment to tune things. On the fly balance adjuster circuits have been offered by several folk over the years. Theory is good but the practice is, at best, "meh". Stripped a couple out that popped the converter.

I'd not use one of those on a compressor, balancing for the hard load is difficult. Maybe on something undemanding like a lightly worked machine tool would be OK. Thats where the ones I made went. Best thing to do is to strap a full size rated idler motor on and make it an RPC. Might well be cost effective when compared to buying new components to roll your own and saves all the work.

Clive
 

mksj

Member
Seems to be just a static converter with what appears to be two start and 4 run capacitors. The 3rd leg can only be measured when the motor is running "Only DPS check the voltage is the output voltage 2 phase and the output voltage 3 phase when the only motors movable". A true digital output would show voltage on the 3rd leg. I also saw a picture of the insides and it had minimal semiconductor devices. Overall lack of information indicates somewhat deceptive description. Also at the price they are charging there are better simple VFD options.
 

rons

Active member
Since the fishing restrictions have been a little tighter for sharks and the consumers of shark fin soup have diminished, what do you expect?
Those shark fishermen had to be re-trained to make more useless products.
 

okrejci

New member
Greetings,

I´ve been using a MY-PS-2 on my 1 hp drill press for a couple of months with no problems. It´s only for motors, not welders, transformers, etc.. I bought mine according to amperage, the power rating is general.
Reading the reviews, negative ones seemed to come from people who didn´t follow instructions: one unit per MOTOR, not machine.

Good luck,


OK
 

JST

Moderator
Seems to be just a static converter with what appears to be two start and 4 run capacitors. The 3rd leg can only be measured when the motor is running "Only DPS check the voltage is the output voltage 2 phase and the output voltage 3 phase when the only motors movable". A true digital output would show voltage on the 3rd leg. I also saw a picture of the insides and it had minimal semiconductor devices. Overall lack of information indicates somewhat deceptive description. Also at the price they are charging there are better simple VFD options.


Do you have any link to pics of the innards? Inquiring minds want to pry........ IOW, I want to get a handle on what these gomers are actually making..... Been asked several times about them.
 

mksj

Member
I did see a picture posted of the insides, looked there was a bunch of capacitors, not enough electronics to support it being a dumbed down VFD or similar. It was a number of years ago, but I will see if I can find the post/picture. They state: "Only DPS check the voltage is the output voltage 2 phase and the output voltage 3 phase when the only motors movable". A true digital output would show voltage on the 3rd leg.
 

mksj

Member
Picture of the DPS was in one of the Amazon reviews where it did not work, review/picture is gone when I looked. It was mostly capacitors in a box, it may have had some digital switching circuitry. Seems like censorship is everywhere.
 








 
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