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Regarding the motor spec'd below, I need help wiring the motor and capacitor to get the unit up and running.
The motor is:
Ashland Hyst Synchronous Motor
60 hz
1/40 hp
uf 3.0
phase 1
115 volts
rpm 1200
I purchased a 3uF capacitor (370VAC), with the understanding that the cap was needed to start the motor.
So, how should wiring go? The motor has a black, green and combined blue/red wire. The cap has 2 terminals.
Any insight would be appreciated.
Follow Ups:
OK, I'll take shot here. The combined motor wires (blue/red) should be connected to AC hot (in the US, the black wire). The other two wires (black and green) should be connected across the capacitor (one wire at each end of the cap - the capacitor is non-polarized), with the AC neutral (white in the US) connected to (most likely) the black motor wire and its associated capacitor lead. If the motor runs in the correct direction, you're fine. If not, switch the AC neutral (white wire in the US) to the green motor lead.
We have a winner. Thanks Richard P. Your recommendation worked.
Thanks to all who have helped with this.
Pat
Glad it worked. BTW, that's a big motor - what are you driving with it? Curiosity and all. Cheers.
-R.
I was going to use it on my DIY table. Not sure if I can tame the motor enough or not. It runs very nicely, though.
Thanks again for helping.
Whilst I have no experience with the Ashland motor it sounds like you need a Steinmetz connection*.
For this connection the AC supply goes across two of the three motor windings. The capacitor connects between one of these terminals and the third (free) winding, so the three mconnections are:
Phase 1, AC supply and one end of capacitor.
Phase 2 and AC supply only (other phase, natch)
Phase 3 and other end of capacitor only.
The order of the windings will determine the rotational direction of the motor. If you wire it up and the motor runs the opposite way to that required, simply swap terminals 2. and 3. above.
AC rated capacitors do not have polarity, so it doesn't matter which cap terminal is used for which connection.
Before you start wiring, check the resistance between each of the three possible pairings of motor wires (green to blue/red, black to blue/red and green to black.) They should all be within a few percent of each other. If this is not the case get back to me.
It should be noted that the Steinmetz connection has several drawbacks. The third phase created by the capacitor is only approximately correct, and even then only at one value of load. It is usual to have this occur at the highest continuous load and for that to be no more than 80% of the design rating for the motor. At all other loads the phase is further off, one effect of which is that the start torque for the motor is greatly reduced, often less than 20% of design rating.
The practical upshot of this is that you may find that the 3 uF value doesn't give you the best phase balance for your load. You may need to try different values to get closer to balance.
*One caveat, generally the capacitor size for a Steinmetz connection on an induction motor is 70uF per kW motor power. Your recommended cap is about twice that but the extremely poor efficiency of the hysteresis motor would probably be enough to create that difference.
Mark Kelly
Mark, that's very interesting. I assume it would be possible to build a power supply that supplies 3 AC waves for the motor that are exactly 120 degrees apart? Would that overcome the potential hard-to-predict oscillation that you mentioned? Would this lead to a much quieter and smoother turntable drive?
What would the "best" frequency be for the power supply to generate? Is there a set of formulas around that an ordinary statistician might be able to understand for calculating the optimum voltage, frequency and current requirements for the power supply, given the motor's load, speed, etc.?
Actually, this is probably all too complicated for a forum like this. Could you point me in the right direction for exploring these concepts?
Thanks!
"Knowing what you don't know is, in a sense, omniscience"
The further info suppled by Banpuku makes it obvious that this is a two phase motor not a three phase one. His initial mention of three motor wires sent me off on a tangent.
For a three phase motor it is certainly possible to build a three phase drive. See article from Clarisonus but note that I don't use this design any more as it's a bit tweaky to get right. Also note that I think the scale on the speed / torque curve is wrong, the actual speed at the torque plateau should be 1800 RPM.
Optimal frequency is determined by rotational speed required, as it is for any synch motor. Simply multiply the speed by the number of pole pairs and divide by 60 eg for a 6 pole motor (3 pairs) running at 1200 RPM the required frequency is 3 x 1200 / 60 = 60 Hz.
Optimal voltage depends on application and usually there's a tradeoff between noise and dynamics. I always make it variable so it can be tweaked to suit. Rated voltage is always a good place to start.
Current follows voltage unless you build a constant current supply. I've tried that and didn't think it offered anything interesting.
Mark Kelly
I'm currently rebuilding an Empire turntable using the very same Papst motor you worked with in the Clarisonus article. I had seen your motor controller in the DIY forum and have been fumbling my way around to a DIY solution using 3 T-amps. Still a work in progress, but I appreciate your pointers and suggestions.
BTW, I'm a big fan of your posts on motors in various forums, and have collected quite a few of them.
Thanks!
"Knowing what you don't know is, in a sense, omniscience"
Mark,
Just for clarification, there are actually 4 wires that terminate to 3 connectors.
Black wire
Green wire
Blue wire + Red wire that terminate into a single connection
Any further insight would be helpful.
Thanks,
Pat
Mark,
We have a winner. Thanks Richard P. who gave the correct wiring.
Thanks to all who have helped with this.
Pat
I don't understand exactly what you mean by "terminate into a single connection". Can you post a phot?
If the blue and red wires are separable, can you measure all the possible pairs (there are now 6 of them)?
Mark Kelly
Mark,
Per your request
Pat
Hi Mark,
Thanks for the input. the resistance between the wire pairings is not within a few percent. See below:
black - green: 247 ohms
green - blue/red: 46 ohms
black - blue/red: 197 ohms
Any further thoughts on this?
Thanks,
Pat
There's a body of work on asymmetrical three phase motors but it's not something with which I am fimiliar. I've appended a paper on the general theory.
In this scheme the AC voltage is applied between the two highest impedance points (black to green) and the capacitor goes to the lowest impedance (eg from green to blue/red). What you do if the motor turns backwards I don't know.
Mark Kelly
This is only an educated guess based upon working on my ROK this weekend. Use any of this information at your own risk.
Cap should be (must be) non-polar so connect it either way.
Motor should be 2 Phase?????
Have you taken resistance measurements of the windings? 2 independent windings? My Phase 1 winding was about half the resistance of my Phase 2 winding.
Getting the manufacturer's info on the motor would be preferred but here's the guess:
Blue and Red to AC Neutral.
Black to AC Hot (If Black is Phase 1)
Green to Cap to AC Hot (If Green is Phase 2)
Mike
Mike,
Thanks for the response. I measured the resistance across the 3 different wire combinations. Here is what I got:
black - green: 247 ohms
green - blue/red: 46 ohms
black - blue/red: 197 ohms
I contacted ashland and they said they do not have the wiring schematics, so I am out of luck in that regard.
I tried connecting the 3 AC wires to each possible capacitor and motor wire combination. Each time, the fuse tripped. So, something is going wrong. The motor spins freely, so I doubt it is a mechanical issue.
Any thoughts?
Pat
Mark has more experience with different motors so I would defer to him.
My Phase 1 winding had 1/2 the resistance of my Phase 2 winding so your motor is clearly much different at a 1/4 ratio. If Green to Hot and Hot to Cap to Black didn't work, I am out of suggestions.
Good Luck!
Mike
Contact them directly. I am sure they can send you the electrical schematics for the motor and cap wiring.
Blue as a color could be random or it might be a European wiring designation. You see blue and brown commonly with Euro spec wiring.
If the blue and red wires are siamesed, I suspect these are for the line input. They would go to the right side of the motor run or start cap. The left wire would feed the motor. Now is the green or the black the ground wire or the wire feeding the cap signal to the motor? This is the tricky part.
On my US Rek O Kut Ashland motors they have 4 wires coming out. One is white and orange, another is white and black and the other two are white and green.
On my B12H the cap is elliptical and I will base this information on the writing on the cap.
The left side of the cap is attached to the white/orange which feeds the motor. The right side connects to the line and the two white with green wires. The white with black goes to the neutral.
I hope this helps, but Ashland should come through for you.
One last thing, the uf of the cap is probably based on the frequency and voltage of the AC. Your 3 uf cap might be for 50 hz 240 volts. If so you might need to drop to a 2 uf cap. Ashland's technical folks can probably advise you on this as well.
Good luck with the motor!
Jim
"Help support our school's Music programs"
Jim,
Thanks for the response. I measured the resistance across the 3 different wire combinations. Here is what I got:
black - green: 247 ohms
green - blue/red: 46 ohms
black - blue/red: 197 ohms
I contacted ashland and they said they do not have the wiring schematics, so I am out of luck in that regard.
I tried connecting the 3 AC wires to each possible capacitor and motor wire combination. Each time, the fuse tripped. So, something is going wrong. The motor spins freely, so I doubt it is a mechanical issue.
Any thoughts?
Pat
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