Motor CFM @28"

[rwdford]

Another thing I would like to test is some Ametek 240V 50Hz motors

What are the best flowing single stage Ametek 240V 50Hz motors and any idea what the outer diameter is?

Many thanks

[Tony]

I can only conclude that MCB's are unsuitable and will only protect a circuit from very high starting amperage or sustained amperage higher than the rated running current but with a very "slow blow" operation

Fuses are looking like the Only option at this point, I will get some different fuses and test them to find a decent solution

Yup.
MCB's are mostly used at the power distribution board to protect the down stream wiring.
Protection of the wiring and circuit isolation is their only function.
The curves are always pretty long (usually "C" curve).

Standard simple ordinary fine wire fuses, are low cost, readily available, and pretty ideal for our purpose.
That is what I would use.
And as you say, a bit of experimentation is in order.

[RACEPUMPER]

Ametek 119996 is my pick for single stage.
119998-08 for two stage. Both are approx. 155mm diameter.

I am one of the 3 phase guys, I looked at the keemo and another similar called kyotto.
Low safety, minimal adjustment.
I just went with Bruce's units x 3.
Once your targeting your test pressure and getting 28.00 not 27.90 or 28.10, you smile quietly.

Jim

[rwdford]

Cheers Jim, that is one of the motors I was looking at since it can work with 50Hz and the CFM @44" is very good

About the controller yes I think the PTS motor speed controller is best, however I have got the Kemo controller to work very well

The Kemo controller comes with one 400K pot (they say it is 470K in the instructions but it is really 400K)

The controller actually turns on at 326K resistance to be exact and turns off at 350K, if controlling the speed of 4 motors the ideal combination of pot's are 250K, 100K and 20K for the fine adjustment all simply wired in series to make 370K total

When adjusting just 2 motors using a 50K pot I can easily fine adjust the vacuum level from 43" to 45" or so full range, dialing in exactly 44" is both easy & fast!

One negative about the Kemo controller is that it can only be run with 16A max so 3 x 5A 240V motors, however a second controller can be used and controlled with the same B250K, B100K and B20K stereo pots just use one channel wired in series per controller

I can also say for sure the voltage drop in and out of the controller at max speed is zero so you get full power to the motors, I had previously thought there was a voltage drop but that was due to cable rather than the controller


Having said all that the PTS controller is obviously easier to set up and much more capable in terms of max running amps, plus some other useful features like the soft start, I just did not realise it can work with 50Hz 240V

[Tony]

I just did not realise it can work with 50Hz 240V

Bruce's controller consists of three seperate parts.

There is a small circuit board (that is universal) and has switches fitted to select 50hz/60Hz operation as well as select other options. This board contains a small miicrocontroller, and is software driven.

This small circuit board requires 24 volts ac to both power it, and provide exact time and phase syncronization to the mains frequency.
If you source a suitable 24 volt transformer locally (wherever that is) the primary will then suit your local mains voltage and frequency.

The third item is the "random fire" SCR power block that should have voltage and current ratings to suit the application.
These are available up to 150 Amps continuous rating, and with a suitably large heat sink should do the job easily and be just about indestructable.

[rwdford]

Thank you Tony, you have a wealth of knowledge very helpful

After looking more into moor efficiency single stage is best and with a large ID tapered entry rather than flat, 5.7" OD through flow is most practical for the PTS bench and single stage tangential discharge is most efficient of all for moving a lot of air, multi stage is for creating higher vacuum levels which may be great for lifting dirt but not so good for moving lots of air for the lowest Amps

I also think that the CFM figures quoted by manufacturers is realistically around 8 to 10% higher than the CFM measured with a true sharp edge orifice @91.14CFM per square inch, not a big issue but useful to know when selecting motors

About the 120V motors am I correct in thinking that they could be wired in pairs in series with a 240V supply and used as normal with either Kemo or ideally PTS speed controller? I think the little 240V SF120's are wired like this using pairs of 120V motors

It is amazing how almost all commercial benches run all the motors at full speed and cfm is varied with two control knobs one of exhaust and inlet, with variable speed the motors should have a very long life! and a lower electric bill as a bonus

Cheers
Jason

[Tony]

Am I correct in thinking that they could be wired in pairs in series with a 240V supply and used as normal with either Kemo or ideally PTS speed controller?

That should be true in theory, and will certainly work.
But...
The motors must be truly identical, and some people here have struck problems with series connected motors that do not share the voltage equally once the motors start to age.
One motor gradually hogs more power over time, and dies, often killing its companion in the process.

The accumulated Forum wisdom suggests not to do it.
If you have 220 to 240 volts available, use a single contoller with multiple 220 to 240 volt motors.
Best to seer clear of 120 volt motors unless you plan to run them (and their controller) directly off 120 volts.

[rwdford]

That is great Tony, thank you I will stick with 230 to 240V motors

This forum is incredibly useful!

[Malvin]

Tony Wrote
Best to seer clear of 120 volt motors unless you plan to run them (and their controller) directly off 120 volts.

I had to go with 120 volt vacuum motors & My motor speed controllers are 120 Volts I use two of them they each run two vacuum motors
I do check the voltage & amps once a week on the vacuum motors that are on the Payne solid state speed controllers So far these motors
are drawling the same Volts & amps I also check the pot controllers they have 90 volts at them when not being used when I turn the motors on
two per controller the volts jump up to 120 volts .

I did not have enough space in my main electrical panel to use the 240 or 230 volt breakers or my sub panel So i use one 100 amp breaker to fed
my sub panel & use a 20 amp breaker for each vacuum motor except for the four motors that are being controlled by the Payne solid state controllers .

I want to add This thread as been very E/I for me Thanks very much Tony with your answers & thanks to all that has posted in this thread .

[rwdford]

I want to add This thread as been very E/I for me Thanks very much Tony with your answers & thanks to all that has posted in this thread .

I completely agree, thank you all for your detailed responses, much appreciated!