I have two motors from the "timers" in scrapped microwave ovens.
One is 2.5rpm 30Vac 4W and the other is 5rpm 21Vac 3W.
They are very tolerant of supply voltage. I have run them at voltages down to ~1/3 of rated voltage and they start up and run well. I cannot stall either of them.
But,
they start in a random direction of rotation.
I want one, or other, to always start in the same direction.
How do I ensure they always start and run forward?
I plan to build a mains driven clock to monitor the "time lost" during power cuts/failures.
At the moment I only know I have had a recent power cut, because most of my "other" clocks have stopped/reset.
As an aside I could mount the Mains clock next to one of my "radio" clocks to monitor when the mains is running Slow and when it is running Fast, or when it is nominally 50Hz.
One is 2.5rpm 30Vac 4W and the other is 5rpm 21Vac 3W.
They are very tolerant of supply voltage. I have run them at voltages down to ~1/3 of rated voltage and they start up and run well. I cannot stall either of them.
But,
they start in a random direction of rotation.
I want one, or other, to always start in the same direction.
How do I ensure they always start and run forward?
I plan to build a mains driven clock to monitor the "time lost" during power cuts/failures.
At the moment I only know I have had a recent power cut, because most of my "other" clocks have stopped/reset.
As an aside I could mount the Mains clock next to one of my "radio" clocks to monitor when the mains is running Slow and when it is running Fast, or when it is nominally 50Hz.
My theory on these is a little hazy (we covered all this at college but its a long time ago) but I seem to remember that many clock motors (or related mechanisms) had a little mechanical ratchet/gadget that engaged if the motor went the wrong way and kicked it the correct way.
Amazingly searching for synchronous and shaded pole motors brought Rod Elliot up.
Clock Motors
Amazingly searching for synchronous and shaded pole motors brought Rod Elliot up.
Clock Motors
Yeah, clean and lubricate the little clip on the end of the motor. Thin straight chain lubricants tend to evaporate in a few years, to say nothing about the effect of dirt. I don't recommend synthetic oils, because all of the low quantity sources are so polluted by the requirements of automotive engine lubrication. Detergent oils tend to suck moisture out of the air and cause rust. I'm using US pharmacutical laxative mineral oil in my electric motors because it comes in pints, and pretty much is guarenteed to not have zinc aluminum or any other food supplement in it. The FDA would not be amused by such content. I do check a sample from each bottle on a stove in a stainless steel cup (over low fire) to make sure it is not a 5w mixture of volatile compounds and sludges. The volume should not decrease after 8 hours of a low fire burner. You can buy high quality non detergent no anti rust metal content mineral oil as "turbine oil" in 5 gal buckets from Exxon Mobil, Shell, etc. SUS 22 is approximately the viscosity of 5 w transmission oil. I don't know where to buy small quantities of "ester oil" (which is what mobil 1 is) without the additives for either autos or refrigerators.
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I have recently repaired the clock on the Old Town Hall, in Weymouth and the type of motor you require is either a phase sensing motor, with a starter direction capacitor, ebay about £8 or as previously suggested a synchronous motor with a direction corrector mechanism.
See synchronous motor | eBay
and take your pick.
Or from a garage/car boot sale, acquire an electric clock, that will have the correct motor on it, if you really want to stay mechanical.
See synchronous motor | eBay
and take your pick.
Or from a garage/car boot sale, acquire an electric clock, that will have the correct motor on it, if you really want to stay mechanical.
I tested both motors.
The 5rpm ran accurately, the 2.5rpm ran slow, about 1¼% slow.
So I opened the slow one up to find the non working anti-reverse mechanism and why it ran slow.
There is no anti-reverse mechanism.
It ran slow because the compound gearbox has a divide by 303¾ instead of divide by 300.
"made in China"
I now have the 5rpm driving a (formerly) battery wall clock (it cost me £1.99 in ASDA a couple of days ago).
The converted clock runs well. Now a sweep second hand instead of a pulsed second hand.
Lost 1sec in the first hour, gained 13sec in the next 9hrs (overnight), lost 6sec in the next 5hours. In 14hours it is at a net 6seconds error. That tells me that the UK generators are trying to maintain that accurate 50Hz mains frequency, in the longer term.
The "motor" is mounted on the back making the clock 47mm deeper than the original. I won't be digging a hole in the wall !
I have not opened up this 5rpm motor to see if there is an anti-reverse mechanism.
I will have to do that.
Just dawned !!! The motors are almost certainly the rotating turntable drivers, not timers. They would not need a "correct" direction for a turntable.
The 5rpm ran accurately, the 2.5rpm ran slow, about 1¼% slow.
So I opened the slow one up to find the non working anti-reverse mechanism and why it ran slow.
There is no anti-reverse mechanism.
It ran slow because the compound gearbox has a divide by 303¾ instead of divide by 300.
"made in China"
I now have the 5rpm driving a (formerly) battery wall clock (it cost me £1.99 in ASDA a couple of days ago).
The converted clock runs well. Now a sweep second hand instead of a pulsed second hand.
Lost 1sec in the first hour, gained 13sec in the next 9hrs (overnight), lost 6sec in the next 5hours. In 14hours it is at a net 6seconds error. That tells me that the UK generators are trying to maintain that accurate 50Hz mains frequency, in the longer term.
The "motor" is mounted on the back making the clock 47mm deeper than the original. I won't be digging a hole in the wall !
I have not opened up this 5rpm motor to see if there is an anti-reverse mechanism.
I will have to do that.
Just dawned !!! The motors are almost certainly the rotating turntable drivers, not timers. They would not need a "correct" direction for a turntable.
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You might find these interesting Andrew,
National Grid: Real Time Frequency Data - Last 60 Minutes
Dynamic Demand
Edit... look at the scale on the second one.
National Grid: Real Time Frequency Data - Last 60 Minutes
Dynamic Demand
Edit... look at the scale on the second one.
Can't help with the motors, but I used to keep track of down time of my local electric company in the same way. I had an old electric clock that plugged into the mains and kept good time. It was easy to compare it to my battery powered clocks to know how long the power was out.
These old clocks are easy to find and usually very accurate.
These old clocks are easy to find and usually very accurate.
Yes Mooly,
I was a contributor to the Thread about the accuracy of the Mains Frequency.
Many in that Thread did not appreciate the energy available from the "flywheel" effect of all the synchronised generators. Even when explained they refused to believe !
It's the "flywheel" effect that supplies instantaneous changes in demand. The steam turbine or gas engine then charges up the flywheel "after" the event.
It's a bit like instananeous demand of an amplifier being met by the capacitors. The rectifier then catches up after the event.
50.13 Hz a few minutes ago. They are catching up...
I remember being taught at college about how long in time it takes to bring a generator set up to speed and to synchronise it to the grid.
Dinorwig hydro generating station in Wales is another interesting "peg" in all of this as it can spin up to full output in a couple of minutes and is used for "emergency" generation at peak times. One bizarre fact is that the water used from the upper reservoir is recycled back when demand falls... I guess when you are the national grid the costs of doing that don't figure.
https://en.wikipedia.org/wiki/Dinorwig_Power_Station
The bit on "self starting" and starting a totally dead grid is something I hadn't heard of before.
I always wondered what happened to a clocks timekeeping when the little synchronous motors used suffered increased friction either in their bearings or in the external gearbox but they always turn at the correct speed (or stall). I think you commented on how much torque they had somewhere.
I remember being taught at college about how long in time it takes to bring a generator set up to speed and to synchronise it to the grid.
Dinorwig hydro generating station in Wales is another interesting "peg" in all of this as it can spin up to full output in a couple of minutes and is used for "emergency" generation at peak times. One bizarre fact is that the water used from the upper reservoir is recycled back when demand falls... I guess when you are the national grid the costs of doing that don't figure.
https://en.wikipedia.org/wiki/Dinorwig_Power_Station
The bit on "self starting" and starting a totally dead grid is something I hadn't heard of before.
I always wondered what happened to a clocks timekeeping when the little synchronous motors used suffered increased friction either in their bearings or in the external gearbox but they always turn at the correct speed (or stall). I think you commented on how much torque they had somewhere.
This is actually quite common, see Wikipedia: Pumped storage / worldwide use
Approx. 104GW of pumped-storage facilites worldwide, 20GW in the US. Compare it to the 100GW of nuclear power capacity in the US, not really a bizarre rarity.
Rundmaus
Pumped storage (there's another even bigger in Scotland) is one of the VERY FEW mthods of storing Wind Power. The Wind Power that we the consumers are paying the wind generators an enormous fortune to build. And for each Wind Farm that does not use pumped storage we MUST build a Parallel generator as back up when the wind does not blow or it blows too hard.
Wind Power could be the downfall of affordable electricity, whereas Pumped Storage is very efficient at providing quick start up power that we cannot do without.
I think wind power is a non starter as a renewable energy source. We have a big wind farm off the coast here (south of Barrow) and "the cable" came ashore on the seafront off the Fylde coast. One cable that runs in a small channel down the middle of the road/s to a local main substation. There isn't much flowing through that !
Whats even more worrying is the way electrical energy usage is calculated and planned for. Its taken as around 1.35Kwh per household. Thats fine as long as the gas lasts. To heat homes by electricity would need that figure increasing at least tenfold. Non of the infrastucture, cabling etc etc would cope.
The 90MW windfarm that impressively claims to power 65000 homes would actually power under 6000 homes like ours that are all electric. And when the wind 'aint blowin, or its too windy (as it could be today)...... we freeze in the dark.
Now tidal power, such as blocking a large area like Morcambe bay could have great potential.
Whats even more worrying is the way electrical energy usage is calculated and planned for. Its taken as around 1.35Kwh per household. Thats fine as long as the gas lasts. To heat homes by electricity would need that figure increasing at least tenfold. Non of the infrastucture, cabling etc etc would cope.
The 90MW windfarm that impressively claims to power 65000 homes would actually power under 6000 homes like ours that are all electric. And when the wind 'aint blowin, or its too windy (as it could be today)...... we freeze in the dark.
Now tidal power, such as blocking a large area like Morcambe bay could have great potential.
wave power and tidal power are virtually guaranteed.
But they are both expensive.
It's such a shame that we are building a new bridge across the Forth at Billions of £s and that could have paid for a barrage (to carry the motorway standard road) across the Forth with locks for sea traffic.
The energy company/ies would only have had to pay for the generators. That would have been cheap and guranteed energy. Even thouigh the East coast is not nearly as good for tidal as the west coast Solway and the Severn estuaries. We really need both of these schemes, no matter what the environmetalists object to.
But they are both expensive.
It's such a shame that we are building a new bridge across the Forth at Billions of £s and that could have paid for a barrage (to carry the motorway standard road) across the Forth with locks for sea traffic.
The energy company/ies would only have had to pay for the generators. That would have been cheap and guranteed energy. Even thouigh the East coast is not nearly as good for tidal as the west coast Solway and the Severn estuaries. We really need both of these schemes, no matter what the environmetalists object to.
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