Putting the cart before the horse…..Three Phase power question???????

[TheOldHokie]

My mill is 2hp 220v 3 phase, powered with a Phase-a-matic PAM-300 solid state 1 phase to 3 phase converter.
It has run flawlessly for over 30 years.
I pulled the power from an unused 30a 220v dryer circuit.
I'm told that this setup will provide less than full power, but I have never been able to detect any evidence of that.
I also run my 220v 3 phase diamond/alox tool grinder on the same circuit, but not at the same time.
I have a 12-4 rubber cord from the converter connected to the mill through a 20A 250V 3 phase twist lock cord cap, and just disconnect it from the mill and connect it to the grinder's cord with the same cord/cap.
I forward/reverse power tap with large taps (1"-8 UNC & 1"-12 UNF) and have taken heavy enough cuts to make the belt slip with no problems from the converter.

1 to 3 HP Phase-A-Matic™ Static Phase Converter, UL Certified. Heavy Duty - PhaseAMatic

phase-a-matic.com

I suppose if I had it to do over again, I might go with a VFD, but this was cheap & fast to acquire & hook up.
I think I installed it & was up and running in less than an hour after the converter was delivered.

Phase-a-matuc is quite ckear - that is a motor starter and does not produce 3 phase power. Your 3 phase motor is running with a total phase loss. In an industrial machine that is considered a serious power fault and a VFD would shutdown the system to protect the motor from damage.

Dan

STARTS THREE-PHASE MOTORS FROM SINGLE-PHASE POWER TO RUN AT 2/3 RATED HP*

IMPORTANT: Static Converters do not produce constant 3-phase power; they “jump-start” your 3-phase motor to run on single-phase power. Be sure to read all information provided.

 

[TheOldHokie]

So you are using "Method 1” in their description?

METHOD #1

Using the Phase-A-Matic™ Static Converter only will produce approximately 2/3 normal HP.* This method is inexpensive, the most popular, provides excellent results on most machines tools and numerous other uses. Motor speed is not changed. Most two-speed motors, power feeds, coolant pumps, etc., will operate normally. Motor will instant reverse. There is nothing to change. All switch gear will work normally. *Refers to wye-wound motors; delta-wound motors will run at 50% rated HP. Delta-wound motors are very rare in the USA, occasionally being found on some imported equipment, and are particularly found on German and Italian machines.

If the motor is 400/240V dual voltage capable there will be a wiring box with six possibly nine leads and wiring diagrams for selecting which voltage you want. 400 V wiring will be Wye and 240V wiring is delta. Do not confuse this with a Wye service entrance from the POCO. Just that simple.

Dan

 

[Lil Foot]

So you are using "Method 1” in their description?

METHOD #1

Using the Phase-A-Matic™ Static Converter only will produce approximately 2/3 normal HP.* This method is inexpensive, the most popular, provides excellent results on most machines tools and numerous other uses. Motor speed is not changed. Most two-speed motors, power feeds, coolant pumps, etc., will operate normally. Motor will instant reverse. There is nothing to change. All switch gear will work normally. *Refers to wye-wound motors; delta-wound motors will run at 50% rated HP. Delta-wound motors are very rare in the USA, occasionally being found on some imported equipment, and are particularly found on German and Italian machines.

Correct!

 

[WI_Hedgehog]

Is that stamped on the motor somewhere?

Every electrician we've called in has first ohmed it out to verify. I know just enough to know to not mess with 3-phase because I'm gonna wreck something.

I would say ohm it out to be sure you have what you think you have. We regularly have motors re-wound when servicing machines and they can be wound any way you want, we just stick with "as delivered" because then everything matches up and if it worked for 20 years as-is it'll work another 20 years, but I've seen some funky wiring on stuff because it worked better for some odd application long-lost to the anals of history (and some guy named "Jack" that retired 20+ years ago). Plus if something is "not right" you'll know it before throwing amps at it, like a failing winding will ohm low and you'll know it beforehand.

 

[lynnmor]

Since you have a step pulley model Bridgeport a VFD would be beneficial, my son has the same machine and uses a VFD successfully. He does that kind of work and I never discussed the device he selected. If you might get into considerable power tapping be sure to get a model that will instant reverse and is large enough to do the job. Usually tapping is done at a low RPM and done with care, the machine will have no problem with it. For a hobby shop, it won't be too much exercise to just power the tap with your muscles.

 

[TheOldHokie]

Know the difference

Here us a duagram showing the basics of a motor starter, true static phase converter, and a RPC.

The starter is just a $10 start cap that momentarily bridges L1 or L2 to the third 3 phase leg. That starts the 3 phase load motor and then drops out leaving the load motor running on single phase input. Motor power is halved, windings run hot, and motor longevity is compromised.

The static converter adds two full time run caps ($20 each) between the single phase input legs and the third 3 phase leg. This generates a rough approximatiin of the third leg but the output is ragged, phase shifted, and poorly balanced. Motor power us reduced by about 20% but its now running on all three windings.

The rotary converter adds an unloaded 3 phase idler motor connected to the output that balances and smooths out the 3 phase waveform. Load motors are then connected in parallel with the idler. Load moter power loss is reduced to just a couple percent.

Dan

 

[Lil Foot]

Probably 75% of my tapping is done by hand, generally only "production" jobs (large number of parts) are power tapped.
I have two hand tapping stands and various hand tapping guides around, but I do power tap on the lathe almost exclusively.

 

[TheOldHokie]

Probably 75% of my tapping is done by hand, generally only "production" jobs (large number of parts) are power tapped.
I have two hand tapping stands and various hand tapping guides around, but I do power tap on the lathe almost exclusively.

And I am just the opposite. i also do some pretty heavy cuts so I need full motor power.

Dan

 

[Sidekick]

I'm more interested in a video about moving a Bridgeport down the stairs into the cellar .

 

[lynnmor]

I'm more interested in a video about moving a Bridgeport down the stairs into the cellar .

I started this trade in 1964 working in a basement tool & die shop. The owner had a dead man installed in the garage floor at the basement steps. He moved all of his machines in and out using it with proper cabling. He had 7 mills, 4 lathes and 4 surface grinders among other equipment.

 

[Sidekick]

I started this trade in 1964 working in a basement tool & die shop. The owner had a dead man installed in the garage floor at the basement steps. He moved all of his machines in and out using it with proper cabling. He had 7 mills, 4 lathes and 4 surface grinders among other equipment.

I think RWS has to go through the living room first with no elevator yet .

 

[Russell King]

Is that stamped on the motor somewhere?

There should be a wiring diagram inside the connection box (or near the connection box) of the motor.

To give you a warning, many small three phase motors are built to bring out many of the winding connections to allow the user to use multiple voltages and amperage ratings so it can get somewhat confusing.

Here is a link to understanding how a simple inverter works.

This is a link to the website of that video that has many good videos to watch for helping you figure stuff out.

The Engineering Mindset

Subscribe now to gain core Engineering knowledge and skills through mind-blowing tutorials The Engineering Mindset was started in 2015 by its founder, Paul Evans. The mission was to help students, engineers and like-minded people learn technical engineering topics through short, simplified...

www.youtube.com

 

[Hugo Habicht]

Just to clarify…How many converters did you use? If more than one why?

I have only one inverter (per motor). It produces three phase voltage from single phase grid.

 

[InTheWoods]

...So this whole “power tapping” thing looks to me like it would "hurt the machine”.

From a beginners perpsctive, doesn’t that "instant reversing" damage the gears of the machine?

I have seen lots of videos of people doing it, but I still have a hard time wrapping my head around how in the world that can be OK to do to a machine. And would I miss not having the capability???????
...


Attention VFD proponents……..

Since I have no experience with VFD’s, any reccomendations on brands? I obvouisly went to Amazon and started looking.

Lots of “cheap options” but they almost seem “too good , to be true” ……

If I understand the power tapping concern it's that slamming your machine from forward to reverse can damage it. From what I've seen, this 'reversing', when done at the motor is super smooth and not stressful. 3-phase motors can be switched from 'forward' to reverse' just by swapping two of their three supply leads. They quickly slow down and start back up in the opposite direction. I'd not do this hundreds of times an hour, but for a guy tapping a few holes in his shop it's never been an issue for me. This is one reason to 'oversize' a VFD in that it can be configured to push out more current and you'll get faster reversing. (Yes - more heat in the motor as a result, hence the limitation on how many times an hour you do this.)

As to brand - you might look at Factorymation. It's all chinese, but seems decent.

I'd probably go with something like this for a 1HP motor - the built-in braking transistor is a good feature (it helps it quickly slow down the motor when you want to stop).

If you want to go VFD, download the 256 page (YES!) manual first and see how comfortable you are - there's lots to learn.

TD400 Series User Manual - Factorymation.com

Industrial automation equipment and controllers at the industry's best prices.

download.factorymation.com

There's also a much simpler 'quick start guide'

TD400 Series Quick Start Guide - Factorymation.com

Industrial automation equipment and controllers at the industry's best prices.

download.factorymation.com

 

[TheOldHokie]

I'm more interested in a video about moving a Bridgeport down the stairs into the cellar .

At

If I understand the power tapping concern it's that slamming your machine from forward to reverse can damage it. From what I've seen, this 'reversing', when done at the motor is super smooth and not stressful. 3-phase motors can be switched from 'forward' to reverse' just by swapping two of their three supply leads. They quickly slow down and start back up in the opposite direction. I'd not do this hundreds of times an hour, but for a guy tapping a few holes in his shop it's never been an issue for me. This is one reason to 'oversize' a VFD in that it can be configured to push out more current and you'll get faster reversing. As to brand - you might look at factorymation. It's all chinese, but seems decent.

I'd probably go with something like this for a 1HP motor - the built-in braking transistor is a good feature (it helps it quickly slow down the motor when you want to stop).

If you want to go VFD, download the 256 page (YES!) manual first and see how comfortable you are - there's lots to learn.

TD400 Series User Manual - Factorymation.com

Industrial automation equipment and controllers at the industry's best prices.

download.factorymation.com

View attachment 165741

We are making too much of this. The "sensitive tapping" option on my mill will power reverse all day long with nothing more than a lever mounted pushbutton switch. In most cases I reverse it multiple times per hole.

Dan

 

[hagrid]

must... resist...

 

[TheOldHokie]

must... resist...

Resistance is futile....

 

[Sidekick]

Mine just has a switch on it for fwd / rev and it works with my static converter.

 

[TheOldHokie]

Mine just has a switch on it for fwd / rev and it works with my static converter.

All the switch is doing is reversing the L1/L2 (aka T1/T2) motor leads. Isnt the switch on the mill?

Dan

 

[Hugo Habicht]

All the switch is doing is reversing the L1/L2 (aka T1/T2) motor leads. Isnt the switch on the mill?

I would not run motor phases through a mechanical switch with an inverter feeding it. Healthier doing the direction of rotation through an inverter function.