VFD Gurus, quick question.

[Larry Edgerton]

I have a 220v 3ph Clausing DP with a 1.5hp two speed motor. I would like to change it over to run on a VFD so I do not have to start the converter every time I want to drill a hole. So......

Will the two speed motor add any complications to adding a VFD?

[Jim Riseborough]

I have a 220v 3ph Clausing DP with a 1.5hp two speed motor. I would like to change it over to run on a VFD so I do not have to start the converter every time I want to drill a hole. So......

Will the two speed motor add any complications to adding a VFD?

Based on my recent experience, you cannot have a VFD with a magnetic type switch in between the VFD and Motor. The VFD i have has 12V switching options to control the VFD remotely. I can turn it on, reverse, forward. I dont know if there was options for the speed though.

Additionally, the VFD itself is a variable speed switch, you can set to whatever you want.

Here is a link to a discussion on another site.

http://www.practicalmachinist.com/vb/transformers-phase-converters-and-vfd/vfd-two-speed-motor-contactor-205361/

[Larry Edgerton]

This DP does not have a magnetic starter. I do not want to change speeds with the VFD. The DP has a Reeves drive.

[Jim Riseborough]

This DP does not have a magnetic starter. I do not want to change speeds with the VFD. The DP has a Reeves drive.

It might be ok direct to the VFD then. Hook it up and try it. What VFD do you have?

[Larry Edgerton]

I have not bought it yet, that is why I was asking. I just got off of the phone with Clausing and it will not be a problem so will order one today. Thanks.

[David Kumm]

Larry, I probably wouldn't shift on the fly. Select the speed and stay with it until you shut the vfd off. I think some can be programmed to allow for momentary motor disconnection but above my pay grade so I just select the speed first. Dave

[Larry Edgerton]

Larry, I probably wouldn't shift on the fly. Select the speed and stay with it until you shut the vfd off. I think some can be programmed to allow for momentary motor disconnection but above my pay grade so I just select the speed first. Dave

That is kind of what I figured I would have to do. The switch is a three position affair with fast and slow on the right and the left and off in the center.

Half of the windings do not work on slow, all on fast. on slow speed it is a 3/4hp motor, fast is 1.5 hp. I figured the dead spot in the middle would be a problem, but not hard to work around..

[David Kumm]

opposite, two poles for fast, four for slow. Consequent wound motor for constant torque. 1800 and 3600 rpm. Dave

[Larry Edgerton]

I thought it was the other way around, but that is the way the fellow at Clausing explained it. It does make more sense. How do the three speed motors work like on sliders? Is it a three speed motor or is it taken care of with pulleys.

Aren't you in the middle of tax season?

Also. I talked to a tech at Factorymation and he said that I would have to shut off the VFD to switch motor speeds, not a problem for me as I mostly leave it in High unless working with metal.

[Doug Ladendorf]

In this case I believe the typical protocol is to connect to the slow speed, and run the hz up above 60 to get higher speeds. I'm not an expert though and did not sleep at a Holiday Inn so get confirmation.

Doug

[Larry Edgerton]

In this case I believe the typical protocol is to connect to the slow speed, and run the hz up above 60 to get higher speeds. I'm not an expert though and did not sleep at a Holiday Inn so get confirmation.

Doug

Running a motor at either extreme of the VFD's rpm capability for prolonged time will create a lot more heat according to the techs at factorymation, so that is not an option. The DP has a machine specific motor I do not want to replace. Shutting it off and restarting is not all that hard. or just select the speed range before starting the the VFD. That is all I have to do to have both, and if for some odd reason I need to cut over 2000, or under 100 I can use the VFD for that.

I know people do it, I am just not willing. My only reason for doing it at all is so I do not have to start the converter to drill a hole. I had a single phase drill press for that until I gave it away last week, and I miss it.

[David Kumm]

Usually you want to stay at high enough hz to help the motor with cooling and only overspeed for short periods as the volt to hz ratio doesn't keep up. If you have a motor that will handle it and 440 voltage, you can program a vfd so that 60hz is 50%. that will reduce the voltage to 240 under normal conditions but add voltage as you increase the hz above 60. I've not done it so talk to someone smarter than me if you try it. Dave

[Phillip Gregory]

I have the exact same piece of equipment you do. Wire the motor for high speed and connect the motor directly to the VFD. Use the drum switch for the low voltage controls. Have "fast" tell the VFD to run at 60 Hz and "slow" to tell the VFD to run at 30 Hz. This will replicate the original behavior of the unit and do so safely.

[Larry Edgerton]

I did not do it that way because I drill some big holes in steel on occasion and wanted to take advantage of the motors low speed. I did it as David suggested, and I am the only one in the shop so it will not be an issue.

[Bill Dufour]

I have always heard that. a two speed motor should be set up for high speed on the vfd. Switching will disconnect the vfd under load and it may burn out permanently. at the least it will trip out on speed switching and the motor restarted each time. If you run it too slow it will not cool enough. add a computer case fan for more cooling.
Probably get more power to the spindle if you toss the reavees drive and use a fixed pulley with vfd speed control. That reaves drive probably eats 1/2 hp or more.
This is not the 1920's anymore so i also recommend HSS drills. they came out during the Great War even if many sellers still try to claim carbon steel is so modern and wonderful.
Bil lD

[Phillip Gregory]

The consequent pole motor in your motor is a constant torque device at 60 Hz and below, just like a VFD. Your motor makes 4.57 ft-lb of maximum torque, and since horsepower = (torque * rpm)/5252, having the same torque at twice the RPM equals twice the horsepower. That is why the spec plate on the motor lists exactly half the horsepower at 900 rpm as it does at 1800 rpm. Running the motor in high speed (4 pole) mode at 60 Hz will give you 1.5 hp at 1800 rpm, and at 30 Hz will give you 3/4 hp at 900 rpm, exactly as if you had the motor wired to run using all consequent poles at 60 Hz. Note that the VFD is a constant horsepower device above line frequency and line voltage, so if you wired your motor low speed and gave it 120 Hz, it will still make 3/4 hp as you would need twice the line voltage (480 volts) to make 1 1/2 hp in low speed mode. That is why wiring the motor in high speed mode and reducing the frequency is the way to go.

Note that some consequent pole motors are constant horsepower- you would wire those up low speed and then increase the frequency to 120 Hz for high speed mode rather than wiring them up high speed and decreasing the frequency for low speed mode. Doing that would preserve the greater low-speed torque/power of the motor.

[Malcolm McLeod]

I did not do it that way because I drill some big holes in steel on occasion and wanted to take advantage of the motors low speed. I did it as David suggested, and I am the only one in the shop so it will not be an issue.

I commission a lot of VFDs in my job. Were it mine, I'd wire the motor to run at 'high' speed (for torque), directly to the VFD as recommended. Then use both 'on'
positions of the switch as the low voltage 'run' command (as Philip suggested), setup via the program. (Or, just use one contact in the switch for simplicity?) Program the VFD to run from 10hz minimum to 60Hz maximum.

I'd probably keep the Reeves drive. Let's assume for the moment you leave it in it's mid-range speed position.

1. Flip the switch to 'run'.
2. Use the VFD's keypad to select your desired speed.
- - If at 10hz its's still too fast, use the Reeves to decrease it further.
- - If at 60hz it's still too slow, use the Reeve's to increase it further.
3. Work.
4. Flip the switch to 'off'. Done.

The duty cycle on a DP is much too low to worry about heat unless you are in a nearly continuous process/production. .....See Dan Friedri (http://www.sawmillcreek.org/showthread.php?250653-How-I-put-a-VFD-on-a-drill-press-for-no-more-belt-changes)ch (http://www.sawmillcreek.org/showthread.php?250653-How-I-put-a-VFD-on-a-drill-press-for-no-more-belt-changes)s' recent thread about his DP!!! (http://www.sawmillcreek.org/showthread.php?250653-How-I-put-a-VFD-on-a-drill-press-for-no-more-belt-changes)

If you are in production environment, don't skimp. Ditch the Reeve's drive; install a fixed ratio V-belt system that gives you the maximum RPM needed in your process at 100% of motor's rated RPM. Buy a USA VFD (i.e. Allen-Bradley or Toshiba) and (Baldor) inverter-duty motor. You won't ever look back.

[Phillip Gregory]

I commission a lot of VFDs in my job. Were it mine, I'd wire the motor to run at 'high' speed (for torque), directly to the VFD as recommended. Then use both 'on'
positions of the switch as the low voltage 'run' command (as Philip suggested), setup via the program. (Or, just use one contact in the switch for simplicity?) Program the VFD to run from 10hz minimum to 60Hz maximum.


The drum switch is a maintained contact switch. The drum switch Clausing used has eight contacts, and many are jumpered to properly couple/uncouple the "extra" three leads coming from the middle of the windings to have the motor run in high or low speed mode. (There is a schematic on the inside of the cover of the drum switch stating which contacts are jumpered and which switches are open and closed in fast speed and slow speed settings.) The VFD will need to look for the "run" command from both the fast and slow positions but get a second signal from either one of these to tell the VFD to operate at a frequency other than default. Thus you will need to jumper across the output of one closed in fast position and one closed in slow position switch to properly get a run signal. I had to move some of the jumpers around to do this on my unit. I then set the default speed of the VFD to 60 Hz and used a signal from a closed in slow position switch to tell the VFD to run at 30 Hz instead as long as the VFD kept receiving that signal. That was the easiest way to do it with my VFD (TECO L510) and it only took three wires from the switch to the VFD to carry all of the signals. I can provide pictures, a schematic, and the values of the various VFD parameters if anybody needs it.

[Malcolm McLeod]

The drum switch is a maintained contact switch. The drum switch Clausing used has eight contacts, and many are jumpered to properly couple/uncouple the "extra" three leads coming from the middle of the windings to have the motor run in high or low speed mode. (There is a schematic on the inside of the cover of the drum switch stating which contacts are jumpered and which switches are open and closed in fast speed and slow speed settings.) The VFD will need to look for the "run" command from both the fast and slow positions but get a second signal from either one of these to tell the VFD to operate at a frequency other than default. Thus you will need to jumper across the output of one closed in fast position and one closed in slow position switch to properly get a run signal. I had to move some of the jumpers around to do this on my unit. I then set the default speed of the VFD to 60 Hz and used a signal from a closed in slow position switch to tell the VFD to run at 30 Hz instead as long as the VFD kept receiving that signal. That was the easiest way to do it with my VFD (TECO L510) and it only took three wires from the switch to the VFD to carry all of the signals. I can provide pictures, a schematic, and the values of the various VFD parameters if anybody needs it.

My basic assumption here is that the OP wants to simplify the DP. With that as the objective, I was advocating the use of only 1 N. O. contact in the drum switch (or 2 - if you want to signal the VFD to run with the switch moved to the 'low' OR 'high' position). This contact would break the low voltage 'run' input to the VFD (assumed to be 24Vdc, but may vary by VFD manufacturer). The drum switch would have no line voltage run thru it at all; it simply becomes an input signal device to the VFD's control terminal, providing only an On/Off command to the VFD.

You'd supply line voltage to the VFD, and then direct wire the motor to the VFD using the high speed taps (and wire nuts as needed).

95% (?) of all operations could probably be accomplished with the speed adjustment of the VFD - and never touch the Reeve's drive. Simple.

Even simpler is to get rid of the drum switch and the Reeve's drive. Install a VFD to provide all switching, variable speed control, and OL protection to the motor; and it's keypad is all the interface you need.
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I'm headed down Dan's path; looking for the right 3-phase motor and playing with how I might mount and couple the motor as direct-drive (no belts/sheaves) on my old Central Machinery DP.