single-phase motor

To cost_us

I will ask a friend who has electrical knowledge, but first, what country are you in? I ask because you say electricity supply is 240 volts; in Australia, we have usually referred to supply as 240, but there is a move to change parts of the system to end up with 230 (plus or minus certain percentages); my nominal supply is 240, but measurement shows it to be near 250 because of some circumstances. I presume the motor you intend to use is 240 volts single phase. Was the person knowledgeable who told you that it would not do what you hope for?

In West Australia, on the other side of a line of longitude decided by the Pope some centuries ago, the voltage is usually declared as 250. Slight differences of voltage should not matter. I will check. But my friend always says, “First define the problem.”

Is there a speed control (electrical)? Do you know the starting system of the single-phase motor?

Without info, it is presumed you may be in U.S.A., and only recently I understood the system in that country, how it is that they have 110 volts and 220 volts, with possibly a 3-phase supply also available for factory type installations, but I do not know the voltage of the 3 phase in U.S.A.

I presume the frequency (Hz) of the motor is correct for your supply.

Alan.

P.S. My friend has just dropped in, read my comment, awaiting your answers if you think it may be helpful. — A.

To cost_us

I will ask a friend who has electrical knowledge, but first, what country are you in? I ask because you say electricity supply is 240 volts; in Australia, we have usually referred to supply as 240, but there is a move to change parts of the system to end up with 230 (plus or minus certain percentages); my nominal supply is 240, but measurement shows it to be near 250 because of some circumstances. I presume the motor you intend to use is 240 volts single phase. Was the person knowledgeable who told you that it would not do what you hope for?

In West Australia, on the other side of a line of longitude decided by the Pope some centuries ago, the voltage is usually declared as 250. Slight differences of voltage should not matter. I will check. But my friend always says, “First define the problem.”

Is there a speed control (electrical)? Do you know the starting system of the single-phase motor?

Without info, it is presumed you may be in U.S.A., and only recently I understood the system in that country, how it is that they have 110 volts and 220 volts, with possibly a 3-phase supply also available for factory type installations, but I do not know the voltage of the 3 phase in U.S.A.

I presume the frequency (Hz) of the motor is correct for your supply.

Alan.

P.S. My friend has just dropped in, read my comment, awaiting your answers if you think it may be helpful. — A.

Hello Alan and thanks for your post.

I’m from Cyprus. the place that I keep my press I can only use a single-phase motor. I asked for converting the supply there to a 3-phase one but it costs more than I can use right now..

that’s why I’m trying to find a cheaper solution… as I saw on ebay there are other presses that work with a 1,5HP single phase motor.. I asked an electrician and when he saw the press he said that the motor that I’m after won’t do the job and he suggested to get a 3HP one that works with single-phase. as he stated: if you have a 1,5HP motor that works on 3-phase, the relevant power with 1-phase should be around 2,5-3HP.

the speed control that you asking me, is the handle at the front right side that accelerates the motor by changing it’sposition, when rotating the handle clockwise. is not electrical.

So, just to recap.. :)

I need to use a 1-phase motor for my press and trying to find out the right motor (HP wise and maybe RPM) for it!

Thanks,
Costas.

RED ball 1961.jpg

Hi,

I fitted a new motor on my Heidelberg 10x15 this month.

It ‘s 1.5hp (1.1kw), 4 pole (1500rpm), and has 150uf starter capacitor.

You’ll also need the single phase starter switch.

The old motor was a nightmare and would dread it would break down mid print run. Luckily It stopped working during washup.

I think 1500rpm is enough for most people.

Mine cost £109 delivered. I would have thought a starter switch wouldn’t cost more than £50. I don’t know if you need a new belt, they sell single phase ones but why I don’t know. Hopefully someone here can clarify.

If the single phase motor can be configured to fit the press, it will power the press as well. The start-up of the motor is not under load with the Windmill press, and it just has to power up the flywheel. Once the motor gets to speed, it should run at the rated horsepower, which evidently was sufficient with the existing motor.

The 3-phase motor will do a better job of strating under load than the single phase motor, but is not necessary in this application, since it only powers the flywheel at start-up.

Does that make sense to anyone else?

Yes, makes sense, although the knackered starter capacitor on my old motor wasn’t enough to start mine. You’re right though, I doubt it needs a great deal.

To Costas, Printing Penguin, jhenry and others,

There are so many possibilities, but the replies so far give an indication of what should be possible. Finding the solution to any problem usually starts with guesses based on what can be seen, and then looking to see if changing something solves the problem.

Thanks for reminding me that the press has a mechanical device to change the speed of the press without actually changing the speed of the motor. The motor normally starts without driving the working parts of the press, only the flywheel, and the speed control is usually able to drive the press at low enough speed when the machine is put into drive.

What proportion of similar presses are running in U.S.A. (and elsewhere) with single-phase motors? At what horsepower? That should answer the most important questions.

Yes, a 3 phase motor is expected to have better starting (and running) capabilities than a single-phase motor, but the single-phase motor should be adequate. There are advantages and disadvantages for both types of motor, but my guess is that (even if 3-phase electricity supply could be made available) it would cost a large amount of money to have 3-phase supply electricity provided by the electricity supply people, so a single-phase motor is the right choice.

To Printing Penguin and jhenry, it depends on the way a single-phase motor is designed, some motors use the capacitor only for initial starting, others use the capacitor to make a pseudo (but effective) 2-phase electricity supply to the motor. In Australia, the first kind usually has a built-in switch operated by centrifugal force when the motor nears normal operating speed. The other kind of single-phase motor depends on the capacitor being good for the whole time it is running, and (unfortunately) the capacitor sometimes does something like wearing out, losing part of its electrical capacitance, which upsets all the effects of changing the electricity to make it appear (to the motor) to be 2-phase; the usual result is that the motor fails.

Since a large bridge under construction in Australia fell down (killing about 35 workers) about the year 1968, much more thought has been given to safety; the suggestion is to make sure the motor is properly earthed (grounded in U.S.A. language) when it is wired in; I have seen many dangerous electrical installations when this was not understood, or the wiring has become faulty. Some of my friends from U.S.A. and Canada have been very wary of our electricity system, but where the installation complies with safety rules, there is little risk, although that slight risk always is there.

To Costas, is there an electrician with a second opinion possible?

Alan.

as Alan states, use an electrcian,.

Hi
I converted a windmill to single phase, 240v (Australia)
It may not have been necessary but I used a larger motor, 3 or 3.5hp from memory. Probably overkill.
I made sure the shaft of the motor was larger than the pulley and then had the pulley turned to suit.
One thing to be careful of is to make sure the motor spins the right way as the platen should only spin the one way. The motor can be altered if it spins the wrong way

Dear friends hi and thanks a lot for all your feedback and suggestions.

The only sure thing is that I’m definetely using an electrician. Electricity is not to play around with..
I had another electrician coming in, but didn’t really conviced me with his answers.. probably because his luck of knowledge on how the press works..

From all you said, I’ll give it a go with the 1-phase motor (1,5HP) that I found and see the outcome. I’m more positive now that it will do the job! Just need some time to have the shaft converted from 18mm to 24mm.

Will get back when ready to update you.
Thanks again,
Costas

Dear friends hi again!

Has anyone use this inverter?

http://www.ebay.co.uk/itm/150791118160?ssPageName=STRK:MEWAX:IT&_trksid=...

to cost us and others

I found some useful information at

transwave inverters

and then at

a layman’s guide to converters and inverters

[on the Internet (Google ? ) ]

I hope you can use the internet facility to look for information and opinion.

There was fairly extensive explanation by the manufacturer, describes the limitations, advantage and disadvantages. Unfortunately it seems there are limits set by legislation in some countries; different legislation in different countries. There should be some people in Great Britain who have used these devices.

Alan.

P.S. at one place I worked, the drive motor to the press was variable speed; the drive motor was fitted with a fan driven by another motor, so that once the electric power was turned on, cooling air was blown through the main drive motor continuously, even when the drive motor was stationary (important). A filter was fitted to keep various kinds of dust out of the drive motor, the fan was fitted with an air filter designed for a truck engine, perhaps Ford brand, something readily available, which reduced the amount of maintenance for the drive motor. — Alan.

Hello, I’m in a similar position too. I have a 3 phase motor (50Hz) on a Heidelberg 10 x 15 and want to put a single phase motor on a 240v supply (50 Hz).

Printing Penguin - Is your replacement motor still running well? Can you let me know which motor you bought and where from? I’m in the UK. Thanks.

I have met with a local motor-winder and taken the old motor with me. Apparently, rewinding the existing motor to single phase would mean it would not produce enough HP. They recommend two options:

Option 1: Single phase: 240v, 4 pole motor running at 1500rpm, 2HP motor (they think it’s best to increase HP slightly when going from 3 to single phase). The motor should have dual capacitors and appropriate switch gear.

Option 2: A phase inverter connected to 13Amp 240v supply, which then powers a 3 phase, 4 pole motor running at 1500rpm, 1.5HP motor, as per original.

Either way the spindle of the replacement motor should be 24mm diameter and 50mm in length - which is apparently a standard motor arrangement.

Apparently, if I opt for the single phase option the frame size of the motor will increase slightly, however, this will fit my windmill as the fixing plate is adjustable.

I’m thinking I’ll go with the single phase option - as I see that Printing Penguin has done similarly and all sounds good. If anyone has any experience of either of these configurations, I’d appreciate your thoughts/advice.

Thanks,
Kevin.

Hi Kevin. It’s still working, although it’s giving off a worrying smell, like burning. It may just be the specific motor I bought, it may be I’ve not mounted it correctly, it maybe next door burning tyres. I have no idea. I just dont leave it alone when the things on and leave nothing flammable within several meters, except for the gallon or 2 of oil in and around the press. /-: I’d have the motor rewound, if you’re not doing runs of thousand at a time I doubt you’d miss the speed.

Further to comments:

From basic physics, consider the following: If 1.5 horsepower will drive the press at normal full speed, then 1.5 horsepower (no matter where it comes from, even from a waterwheel) should drive the press at reduced speed through some kind of reduction gearing, with some horsepower to spare. At reduced speed, the mechanical speed control on the press is something like the gearbox of a car (automobile) which allows an engine to power the vehicle OK. For machines like the Heidelberg platens, is it important to run the air pump at (manufacturer’s designed speed) to keep the “windmill” action working OK? Does reducing the rate of impressions (by using the built-in mechanical speed control) alter the speed of the air pump? If the speed of the motor (shaft speed) is within (say) 10% of the original motor, is there a problem? But if the speed of the motor is (say) double the original, my comment is that there needs to be a change of drive pulleys somewhere.

USA increased the level of teaching of science (including physics?) circa late 1950s, so there must be lots of people of the appropriate age range able to understand and give advice on what motor to use?

My further comment is: to decide if a motor is within its capabilities, run it at normal conditions for half an hour, then the user puts a hand close to the main frame of the motor; if it feels too warm, or smells, call an electrician. But some electrical stuff is now rated for a large temperature rise and still within design limits; I am startled at seeing a permitted rise of 70 degrees Celsius (126 Fahrenheit) of some electronic stuff, that seems excessive to me, I suspect that touching anything at that temperature would cause damage to the human.

An oversize motor probably would survive adverse conditions, such as having dust accumulate inside, better than a motor which is supplied by the manufacturer; also, 3 phase motors usually give less problems, except finding the extra two phases. But there are always compensations and balances in any design; we have observed that if a car (auto) of today’s design is run at maximum horsepower for more than a short time, the cooling system reveals that its design has been influenced [read, reduced size] by styling considerations. Our police cars are often fitted with a cooling system which has been enhanced, so can be driven at higher performance for longer time than the vehicle they wish to intercept. [The pursued vehicle overheats?]

If the set-up is not within the manufacturer’s design limits, the result usually becomes known; occasionally there are recalls, or advice to modify, after-market. That is the purpose of communication between those which use the product.

Any suggestions, anyone?

Alan.

My press, a1964 red ball, came out of a production print shop powered by a 1HP single phase motor, 230V 60Hz, 1725 RPM (so four pole). There were three other, older black ball presses there, all driven by the same type of motor. The motors were nothing special, class B insulation, so they would run at full load with an 80 degree C rise (with a maximum ambient usually 40 degree). You would not want to put your hand on it (65 degrees C is my personal limit when checking by hand)! I observed the older machines being started up with no effort at all by the motors. The one I bought was broken so it will be a while before I can report first hand experience.

to all

Pursuing other information about electrical theory, I found the following, which I suggest most people would refer to someone with electrical theory knowledge; but the basic intention is to explain why some electric motors (the “voltage” is very low, but the effect can be destructive?):

refer to

voltage in shaft electric motors

then go to

Protecting e-motor bearings against shaft voltage — Vehicle … Jun 14, 2011 … Shaft voltages induced by inverters can erode … … . . (with pic)

I have sent a somewhat similar email to several of my electrician friends, and some others.

Alan.

Apology: I should have proof-read my comment more carefully (distraction blamed). One part should have read:

Pursuing other information about electrical theory, I found the following, which I suggest most people would refer to someone with electrical theory knowlege; but the basic intention is to explain why some electric motors (the “voltage” referred to is very low, but the effect is destructive) are designed for intermittent use, not the long-term use of commercial-production printing shops, so have a short life if borrowed from other kinds of service and used for more like a thousand hours per year.

Alan.

Alan,
Those comments come from two different areas:
1. Electric motors supplied from an inverter (soft starter or VFD) are subject to unusual distortions in their supply (high voltage wave fronts and harmonics). These have three effects on “normal” or old style electric motors: Higher than normal voltage drop in the outer windings (near the terminations), higher circulating losses in the magnetic structure (the iron) and low voltage induced across the stator - resulting in current flow through the bearings. That is not good. The answer is to buy an Inverter Duty motor.
2. Motors from some other application like washing machines etc. are often specific purpose designed. These design limitations (based on the applicable standards and regulations) should be understood before applying the motors for a printing press. Often the limitation involves short time operation, duty cycle limits or special ventilation. So like you pointed out one needs to be careful.

I’m adding a new motor to my 12x18 C&P and to the Heidelberg next month, both with VFD. I will be posting the details.

Hugo

Ok, now that I have been able to turn over and run the Heidelberg Platen, here are some of my results:
The motor is a 1Hp, 1725RPM, connected for 120VAC rated at 13.4A.
@Flywheel 175RPM, 1751IPM, 9.5Amp average
@Flywheel 306RPM, 3057IPM, 11.5Amp average
@Flywheel 358RPM, 3583IPM, 13.25Amp average
@Flywheel 459RPM, 4594IPM, 20Amp average
The press was run for these tests with all 4 rollers in place, feeding. So you can see the 1 HP motor is suitable up to a flywheel speed of about 360RPM (about 3580IPH). After that it gets into overload. Also, the third speed would once in a while trip the breaker while starting. The highest speed tested (20A load) would always trip the breaker (requiring start at lower speed - then cranking up).
I hope this will help some of you.

If you haven’t found a resolution for this matter I know that my father has talked to American Rotary for many of his phase conversion needs. They are very knowledgeable and have always seemed to be able to help him out. Here is the link to their site:
http://www.americanrotary.com