are a Dahlander 2 speed motor and a vfd compatible?
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    Default are a Dahlander 2 speed motor and a vfd compatible?

    i wonder if i could, without problems, connect a vfd to my lathe that has a Dahlander 2speed motor.
    the lathe has a lever on the apron to select the high and low electrical speeds and to get from the high speed to the off position the lever passes the low speed.

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    On the ones I have put drives on I left the motor on high speed and controlled with just the drive. You don't want to switch the output of the drive with power on. Probably the simple solution is to disconnect the present switch, wiring the motor on high, then control off-on with the control inputs to the drive, which gives you reverse, also, then switch off the power with the disconnect when you are done.

    There are other solutions.

    Bill

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    The conventional wisdom is that adapting a machine with 2 speed motor is that you must choose one of the speeds and live with that choice.

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    Quote Originally Posted by janvanruth View Post
    i wonder if i could, without problems, connect a vfd to my lathe that has a Dahlander 2speed motor.
    the lathe has a lever on the apron to select the high and low electrical speeds and to get from the high speed to the off position the lever passes the low speed.
    Not hard.

    Select a VFD with "two motor" parameter memory. Program each speed as if it was a different motor altogether.

    Put some sort of electrical "lockout" on the OEM speed selector circuit. Might neeed a relay if the switch back of that lever is uncooperative. Might just need an upstream OFF switch.

    Run with what gives you the appropriate range for the tasking.

    Power-down, tell the VFD to use the "other" motor. Switch the lockout over to it.

    Bet you can "live with" the nuisance easily enough, and that most weeks you won't need to change it atall.

    "Hassle"? Some, surely.

    Not all THAT much for what you gain-back in useful range.

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    I have wired two dahlander motors with VFD's. Both cases I just used the fast wiring configuration and did all the speed control with the VFD.

    Sent from my XT1710-02 using Tapatalk

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    as ^^^^. Choosing high range gives about 50% hp at 1/2 mains frequency, which is the same as your original motor would have put out at that speed. Either leave as fully variable or wire one input (low voltage) to select the "low range".

    Do not use the existing range selector switch and existing contactors with the vfd running as it swaps motor input wires AND shorts three of the wires together for the high speed configuration. Best to wire the VFD directly to the motor. You can use the apron lever and wiring with care. You can also run more wiring and put a variable speed control pot on the apron.

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    Quote Originally Posted by thermite View Post
    Not hard.

    Select a VFD with "two motor" parameter memory. Program each speed as if it was a different motor altogether.

    Put some sort of electrical "lockout" on the OEM speed selector circuit. Might neeed a relay if the switch back of that lever is uncooperative. Might just need an upstream OFF switch.

    Run with what gives you the appropriate range for the tasking.

    Power-down, tell the VFD to use the "other" motor. Switch the lockout over to it.

    Bet you can "live with" the nuisance easily enough, and that most weeks you won't need to change it atall.

    "Hassle"? Some, surely.

    Not all THAT much for what you gain-back in useful range.
    Why bother? A Dahlander motor rated 2 hp at high speed is rated 1 hp at half speed, that is- same torque, half RPM. A Dahlander motor on high speed fed with a VFD will develop the same torque at half speed set on the VFD, the same half hp as you get when you switch the motor run on a normal line. You don't gain anything by changing the motor and have more complication. Leave it on full speed and control with the VFD.

    Bill

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    Quote Originally Posted by 9100 View Post
    Why bother? A Dahlander motor rated 2 hp at high speed is rated 1 hp at half speed, that is- same torque, half RPM. A Dahlander motor on high speed fed with a VFD will develop the same torque at half speed set on the VFD, the same half hp as you get when you switch the motor run on a normal line. You don't gain anything by changing the motor and have more complication. Leave it on full speed and control with the VFD.

    Bill
    At half the Hz. Rougher pulsing rate. Some machines, some apps, the end-luser might not want that?

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    "Leave it on full speed and control with the VFD."

    +1, this is the way to do it.

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    Quote Originally Posted by 9100 View Post
    Why bother? A Dahlander motor rated 2 hp at high speed is rated 1 hp at half speed, that is- same torque, half RPM. A Dahlander motor on high speed fed with a VFD will develop the same torque at half speed set on the VFD, the same half hp as you get when you switch the motor run on a normal line. You don't gain anything by changing the motor and have more complication. Leave it on full speed and control with the VFD.

    Bill
    Dangerous assumption. Although the classic Dahlander configuration is constant torque two speed motors can be made with a range of relative powers. The name plate on the UK built one fitted to my wartime P&W B says its same power on both speeds. Wonderfully steam punk set of oil immersed control gear too with proper lock out between speeds. The modified 220 single phase in - 440 three phase out 10 HP Teco VFD that runs my shop handles it just fine.

    Higher power on low speed is possible although I've never seen such. Back in the day UK built machine tools used some pretty sophisticated two and three speed motors. Invariably large, heavy and shoehorned into a space so small that you'd think they cast the bed with the motor in place!

    Clive

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    thanks for the contributions.
    as i am putting a burnerd multi size chuck on this smaller lathe and i intend to keep it there, i think i will go for the vfd on the high speed.

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    Is this to power a 3-phase 380V motor from a single phase 230V source? Then you'll have to step up the voltage somehow, since these Dahlander motors are not 230/380V star/delta, but 380V only, and star wiring powers one speed (forgot which), and delta wires the other speed.

    I tried this once, and the motor did run, but stalled at the least bit of required oomph, because of the low (230V)voltage.

    Step-up VFDs are supposedly available nowadays, so that's a possibility.

    I simply bought a 220/380 3 phase single speed motor off Marktplaats (i.e. Dutch craigslist).

    Best regards,

    Hans

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    Quote Originally Posted by janvanruth View Post
    thanks for the contributions.
    as i am putting a burnerd multi size chuck on this smaller lathe and i intend to keep it there, i think i will go for the vfd on the high speed.
    I've decided my 3+ HP 10EE's will NOT enjoy that lovely bit of kit.

    My one is now meant to migrate to the 7 HP HBX-360. It can better deal with the extra power than the Rubberflex 9XX both already own. The 10EE already have 2J, 5C, ER 40, plus chucks in magnetic, 2J, 4J, 6J and faceplates. So it isn't as if they are exactly naked and undernourished.


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    Quote Originally Posted by Clive603 View Post
    Dangerous assumption. Although the classic Dahlander configuration is constant torque two speed motors can be made with a range of relative powers. The name plate on the UK built one fitted to my wartime P&W B says its same power on both speeds. Wonderfully steam punk set of oil immersed control gear too with proper lock out between speeds. The modified 220 single phase in - 440 three phase out 10 HP Teco VFD that runs my shop handles it just fine.

    Higher power on low speed is possible although I've never seen such. Back in the day UK built machine tools used some pretty sophisticated two and three speed motors. Invariably large, heavy and shoehorned into a space so small that you'd think they cast the bed with the motor in place!

    Clive
    I only have experience with the standard Dahlenders, but I have read about some of the other configurations. I stand in absolute awe of the things engineers did with only motors and relays. In one DC system, a relay looked at the line voltage and what was coming out of the generator and if the generator was low, would not connect it, while running monitored the direction of flow and would disconnect if there was a backflow, shut down on an overload and give the system time to stabilize before reconnecting. All done with copper, iron, and silver contacts.

    Now you just tell the computer what to do.

    Bill

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    Quote Originally Posted by Clive603 View Post
    Dangerous assumption. Although the classic Dahlander configuration is constant torque two speed motors can be made with a range of relative powers. The name plate on the UK built one fitted to my wartime P&W B says its same power on both speeds. Wonderfully steam punk set of oil immersed control gear too with proper lock out between speeds. The modified 220 single phase in - 440 three phase out 10 HP Teco VFD that runs my shop handles it just fine.

    Higher power on low speed is possible although I've never seen such. Back in the day UK built machine tools used some pretty sophisticated two and three speed motors. Invariably large, heavy and shoehorned into a space so small that you'd think they cast the bed with the motor in place!

    Clive
    Yep, the BTH 3-speed (Dahlander and a separate winding) on my Holbrook is 3 HP and same full-load current rating (+/- 1/2 an Amp) in all three speeds, and I run a VFD into all of them by using a microswitch on the back of the 3-speed lever to put the VFD into "coasting" between speeds then resume - has worked well so far.
    It does mean that the Frankenstein speed switch doesn't operate with volts across it, which is the vital part of the setup, a few other Holbrook users have done much the same.

    Dave H. (the other one)

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    Quote Originally Posted by 9100 View Post
    I stand in absolute awe of the things engineers did with only motors and relays. In one DC system, a relay looked at the line voltage and what was coming out of the generator and if the generator was low, would not connect it, while running monitored the direction of flow and would disconnect if there was a backflow, shut down on an overload and give the system time to stabilize before reconnecting. All done with copper, iron, and silver contacts.

    Now you just tell the computer what to do.

    Bill
    Yahbut.. the silly 'puter too often backtalks, even MUTINIES!

    Old Skewl goods sound like the ASCO Automatic transfer switch?

    Some US Army Signal Corp Colonel, Phil-Thai-Oki & Vietnam IWCS FPTS contract, mid/late 1960's didn't think the OEM manual was simple enough.

    Northrop-Page tasked a certain Seniour Technical Writer with a new manual. Yrs truly.

    Complex? Yah but... Not really that HARD to do the sensing, add a time-delay, take the action, UNLESS countermanded mid-stride. Which was supported, as "mains power" COMMONLY has the odd hiccup when coming back after a traumatic outage.

    Irony? Near-zero of the IWCS sites even HAD utility-mains power to begin with!

    The ASCO's switched only between our own triple Diesel gen sets!

    Did not need to do. Were seldom even ALLOWED to do, other than for routine testing to insure they COULD do.

    As crucial military comms sites of the highest priority, they were fully manned, 24 X 7 X 365. Military staff chose what was online. Not the box of relays.

    "Belt and braces"?

    Welll... Both were taxpayer funded. Of course.

    But at least the ASCO was paid (for) but the one time, not every month for a whole career!

    I like Hopefuldave's solution, BTW.

    Dahlander had a value-add. It is now "paid for". Why cripple it if yah do not HAVE to do?

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    Quote Originally Posted by Hopefuldave View Post
    Yep, the BTH 3-speed (Dahlander and a separate winding) on my Holbrook is 3 HP and same full-load current rating (+/- 1/2 an Amp) in all three speeds, and I run a VFD into all of them by using a microswitch on the back of the 3-speed lever to put the VFD into "coasting" between speeds then resume - has worked well so far.
    It does mean that the Frankenstein speed switch doesn't operate with volts across it, which is the vital part of the setup, a few other Holbrook users have done much the same.

    Dave H. (the other one)
    so i could hook up a vfd in the mains going to the motor and switch between low and high rpm as long as there is a moment of no voltage in between high and low?
    if that is possible i will take it.
    all i have to do is make sure i do not go into reverse before the motor has stopped completely i suppose.
    that mistake already cost me a vfd..

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    Don’t bother with all of that nonsense. Just permanently connect the motor in the highest speed and use the VFD to lower it.

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    I don't know anything about 2-speed motors and don't' own one, but this thread piqued my interest. I have a question.

    Baldor has one and two winding 2-speed motors. A 1HP one winding loses 75% of it's HP at low speed (1/2 speed) and a 1HP two winding loses 56%. With a VFD you lose 50% of the HP at half speed. So by opting to control the speed a with a VFD you would actually gain HP at 1/2 speed? Or at least that would be the case with the motors link to below?

    Baldor 3-Phase TEFC Two Winding Variable Torque Two Speed Motors

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    Quote Originally Posted by ptsmith View Post
    I don't know anything about 2-speed motors and don't' own one, but this thread piqued my interest. I have a question.

    Baldor has one and two winding 2-speed motors. A 1HP one winding loses 75% of it's HP at low speed (1/2 speed) and a 1HP two winding loses 56%. With a VFD you lose 50% of the HP at half speed. So by opting to control the speed a with a VFD you would actually gain HP at 1/2 speed? Or at least that would be the case with the motors link to below?

    Baldor 3-Phase TEFC Two Winding Variable Torque Two Speed Motors
    HP, Torque, and RPM all live in a fixed Mathematical relationship to one another. Look it up. Calculation tools re is online. Also simple.

    Never mind how you GET there on any one or chosen combination of those parameters, be that alternate winding set, VFD, DC motor, or servo.

    For the lower-RPM to NOT lose HP, the Torque would have to go UP.

    Add more "poles" and one can goal for that. Compare 2, 4, 6, 8 pole ONE speed AC motors.

    Fewer poles - worse - pulsed less frequently as the means of reducing RPM - it only gets weaker, and also rougher, "sooner".

    If there was a cheap and easy "all electronic" way around that (a VFD is not..), neither of "cone head" step-pulley belted ratios, nor geared-head ratios, would need to exist.

    Whether stepless variable speed, fixed-count multi-speed, or solitary FIXED speed, the world is full of devices that STILL need at least one mechanical ratio to keep motor size, weight, cost, and performance where it needs to be for pragmatic use.

    IOW?

    Don't expect a lot of "magic" to have been overlooked, lo a hundred years and more, still seeking.

    "VFD" isn't even CLOSE to "new" in concept nor delivery.

    The only thing "new" is that they are now small, light, and solid-state.


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