3 phase conversion digital
- Thread starter minardi
- Start date
Doozer75
Well-known member
I think he means a Phase Perfect device
but I am not a mind reader.
-D
but I am not a mind reader.
-D
Steve from Socal
Well-known member
I think Phase Perfect is what you are talking about? Kinda like an inverter actually IS an inverter with more logic. I think the 10HP is the one you want, hard starting equipment like a compressor I would ask the company about first.
Doozer75
Well-known member
I have got to think retrofitting a single phase 7.5hp motor is much cheaper
than buying a 10hp Phase Perfect unit, even used.
-D
than buying a 10hp Phase Perfect unit, even used.
-D
jar944
Well-known member
Sure but then you can't freely add a bunch more 3ph machines.
Imho a for a single application a vfd is the cheapest option.
theoldwizard1
Well-known member
To the best of my knowledge, ALL electronic phase converter, certainly any that have variable frequency/speed control, convert the single phase AC to DC and then take the DC and convert it to 3 phase AC.
Somewhere in there, they may or may not boost/reduce the incoming voltage to create the proper output voltage. Because the 3 phases are "synthesized", there is feedback circuitry to ensure the proper voltage and phase angle of L1, L2 and L3.
Yes
I see DPS online they are around 400
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jar944
Well-known member
Thats a static phase converter. You only get 2/3 the rated hp from the motor since its only running on 2 of the 3 phases. You want a varible frequency drive.
This one will provide 27FLA off single phase power.
wyliesdiesels
Well-known member
Junk. Dont buy that
fitter30
Well-known member
Compressor have a working unloader? Go by name plate amps double it might want to go up to 20 hp vfd if it needs service factor amps.
walta
Well-known member
The black boxes labeled “digital phase converter” are mostly 1930 technology of a static phase converter with a digital timer to disconnect one of windings after the motor is turning. Note this static converter is poorly for heavily loaded motors of an air compressor and very likely to destroy your motor.
If this is likely to be the only 3 phase machine you are going to acquire (fat chance) get a VFD that will produce real 3 phase power. If you are likely to get a few more 3 phase machines get a rotary phase converter.
Walta
If this is likely to be the only 3 phase machine you are going to acquire (fat chance) get a VFD that will produce real 3 phase power. If you are likely to get a few more 3 phase machines get a rotary phase converter.
Walta
theoldwizard1
Well-known member
I would think that ALL modern digital phase converters would have built in "soft start" capability. With a true soft start, LRA should not be an issue.
walta
Well-known member
Do not be fooled by the word digital.
The low cost devices are a few capacitors a relay and a digital timer.
That do not feed current to all the phase evenly and will damage motors under heavy loads.
The phase perfect looks like a good product but at that price point you can get a VFD.
Walta
The low cost devices are a few capacitors a relay and a digital timer.
That do not feed current to all the phase evenly and will damage motors under heavy loads.
The phase perfect looks like a good product but at that price point you can get a VFD.
Walta
cycle61
Well-known member
The phase perfect is a very good product, it uses the two incoming lines and then pulls off a bit of power, feeds a DC bus, and generates a true third leg with an inverter circuit.
If you need variable speed, get a VFD. If you need to power a 3/ machine on a single phase service and might ever consider adding another machine, go for a phase perfect.
Steve from Socal
Well-known member
As mentioned above, for a single use like the compressor. A single phase motor may be the most cost effective and correct choice. Machine tools particularly CNC with regenerative braking need three phase power from mains or something like Phase Perfect.
Rotary phase converters can work on many machines but the issue with leg balance and hard starts require oversizing for a machine like a compressor. Static converters are just start modes to single phase a three phase motor. An inverter VFD would also be a good choice BUT, the cost of the drive may exceed a replacement motor? A 7.5 HP 1750 single phase motor is about 800.00. How much is a single phase input VFD?
Rotary phase converters can work on many machines but the issue with leg balance and hard starts require oversizing for a machine like a compressor. Static converters are just start modes to single phase a three phase motor. An inverter VFD would also be a good choice BUT, the cost of the drive may exceed a replacement motor? A 7.5 HP 1750 single phase motor is about 800.00. How much is a single phase input VFD?
jar944
Well-known member
$795.20 plus tax and shipping, but you don't have to buy a new starter to make it work like with a single phase motor.
Steve from Socal
Well-known member
Depends on the starter? I have a number of inverters, they are all 480 three phase, the low cost single phase VFD's seem to be hit or miss? I have no experience with them, just what I read on various forums?
jar944
Well-known member
7.5hp 3ph should be a nema size 1 starter, 7.5hp 1ph would be a size 2.