I am in the process of fitting a VFD to a Colchester Student 1800 lathe. I would like to keep the apron forward/reverse lever functionality, as well as the brake function. (Push pedal to stop motor and don't start it again when pedal is released, even if forward/reverse lever is still engaged.)

I am struggling to find a wiring diagram and programming setup of what seems like quite a common requirement. I have downloaded various Huanyang manuals, which refer to Start/Stop/Reset, but not to emergency stop, even though this is mentioned later on in the manual as an option.

Could anyone show me a simple wiring diagram for this setup, and indicate what programming is required?

Also is it essential to fit a braking resistor? I don't need instantaneous stopping. I was wondering of the mechanical brake fitted to the foot brake pedal would mean that I should fit a braking resistor.

Any help would be appreciated.

Sorry to be negative, but no. First you have not given use the exact model of VFD. I cannot find any reasonable source for a manual for a "Huanyang P2". Why don't you ask the supplier for support?
Can you at least give us a part number and a link to the manual?

To be a bit blunt, I think it is a little unfair to buy a cheap VFD with no support from the seller and then expect others to spend time sorting it out.

Robert.

Everybody seems to think that the easy way to run 3Ph machines AND keep ALL the proper switches etc is to use a VFD. It may be the cheapest way to run the motor, but ! You don't say whether it was originally a 3Ph machine ? If so then you must reconfigure from star to delta .It may not be possible to to adapt the original switch gear to the VFDat all or may involve a lot of work to get it to work correctly.

Then there is PLAN B, use a static or rotary converter and just connect it up as 3Ph 415V no messing and all the bits should work as designed ! Not as cheap as a cheap VFD but a whole lot easier ! Good Luck. Noel.

A manual is here:

https://bulkman3d.com/wp-content/uploads/2019/01/HY01D523B-VFD-Manual.pdf

On the bottom left of the diagram in the original post is the 'multi-input'. The bottom half of page 20 of the manual covers this. To make the multi-inputs accept commands, parameter 001 needs to be set to 'external terminal' (bottom of page 26).

Each input pin has 32 possible settings that define its function. You program the pin to do what you want it to do and then connect an appropriate switch to the pin.

Page 37 of the manual is a good start on the wiring diagram, using three of the six multi-inputs. Connect the E-stop to one of the unused three remaining ones.

Too slow typing above post says it all!

Edited By Dave Wootton on 03/06/2023 13:36:26

The braking resistor is switched in when the voltage on the DC link of the VFD rises too high because the slow down ramp timer is set too short. Program a conservative ramp time and the resistor may not be necessary. A fault is usually generated if the DC link voltage goes too high. A big job with a four jaw chuck fitted can result in a mass that is beyond the VFD to control even with the resistor fitted in which case the ramp down time will need to be increased until the machine can be slowed without creating a DCLink fault.

Mike

Program a conservative ramp time AND use the mechanical brake on the machine and the two will fight each other.

Any input you make to this discussion concerning ramp times and braking resistors will be meaningless and could even be misleading without including the mechanical brake as part of that input (which could be a simple as saying 'do not use the mechanical brake at all'.

Isn't the foot operated brake intended to be used for emergency braking of the spindle so it should be connected into the spindle drive emergency stop circuit, this of course may or may not cause damage to the VFD.

If the argument is not to use the method as above then I believe the use of such a device could be termed dangerous and should be avoided for operator safety.

Emgee

Thanks very much for all of the positive posts, they are most helpful.

It seems that the mechanical brake will increase the work the VFD will have to do to bring the motor to a stop and manage the rise of the DC link voltage, meaning that damage to the VFD is more likely. From the point of view of protecting the VFD, would it be better not to use the brake at all, and just use the E stop button?

DC31k raises an interesting point about the mechanical brake conflicting with the ramp down. I think the mechanical brake was useful because just switching the motor off could result in a long slow down as there could be a lot of inertia in the drive train and the job mass. I have used a Colchester with a mechanical brake and I tended to use it for a quite aggressive stop if I just wanted to take a measurement. The ability to program a short ramp down would tend to negate the usefulness of the mechanical brake so I think I would tend to favour a short ramp down and forget the mechanical braking system.

Mike

If you've got your hand in the mangle, stamp on the footbrake with all you've got. Too bad if the VFD doesn't make it.

But to give it a chance, have an E Stop relay which cuts power to the VFD as a result of pressing the footbrake. There's a micro switch fitted to fulfil just this purpose with the original control circuit. The issue over whether the VFD will ramp down or loose control of the spindle doesn't matter, the brake will do it's job. One would expect the VFD to survive a power outage at full speed, so this is no worse than that.

One could also devise a control scheme where this micro switch was the stop input to the VFD, but the VFD must not restart when you release the pedal.

Less savage happenings - having the work shift in the chuck for example - are dealt with in the same way. It would be nice if the VFD survived so telling it to stop asap is possibly the way to do this though it does depend on the features of this particular VFD.

HTH Simon

I don't know about the cheap ones, but mainstream VFDs take both "STOP" and "Emergency STOP" (E-Stop) inputs.
The Stop commeand ramps down under control and the E-Stop slows the motor as fast as possible. Jaust cuttig the power input is not a good idea as there is energy stored in both the rotating mass and the bridge capacitor(s) of the VFD and this may not be managed properly. Applying an E-Stop command and cutting input power may be acceptable as the stored power may be enough to keep the control electronics running until the stop is completed. Correct E-Stop operation may require a braking resistor to pevent overvoltage by genration from the inertial load. Biger drives use DC injection to aid braking. In this case the input supply must be maintained until the motor has stopped. Correct stopping of a machine often requires sequencing and timing. The sequence may include total removal of power at the end. It theory these functions have to be carried out by high integrity approved safety devices. (I always thought it odd that many indistrial E-Stop buttons have separate clip-on switch elements andif these fall off the machine will run but E-Stop won't work. Testing daily doesn't help as it may be the test that finaly broke the switch).

Lathes are particuarly troublesome as the load is so variable. The E-stop may work fine with just a chuck fitted but what if you have a large heavy workpiece acting as a flywheel?
I have designed safety interlock and stop systems for large multi-axis machines with high speed linear motors. These were tested and verified by independant approval organisations.

Robert.

If a mechanical spindle brake is combined with a spindle drive clutch as fitted to a Colchester Chipmaster then the VFD won't be overloaded. In this machine the motor is started using the forward/reverse switch and drive to the chuck engaged by a separate lever activating the clutch. Pushing the lever the other way disengages the drive clutch and gradually activated the spindle brake. The Student may use a similar arrangement but with two levers, one to engage the clutch and the other to drop the clutch out and gradually engage the spindle brake.

However in a more conventional electrical control arrangement the motor may be started and stopped by a buttons engaging and releasing a motor control contactor/s and when a mechanical brake is used it would normally activate a switch that releases the motor contactor to remove drive.

Machines can be fitted with either an Emergency Off or an Emergency Stop. The EMO just disconnects power whilst an EMS arrangement actively stops the machine in a controlled sequence.

If a VFD is used the VFD can be configured to "coast" to standstill when "Stop" is activated in which case there is no regenerative braking and no need for a braking resistor. In this case spindle braking would rely solely on mechanical losses. If a mechanical spindle brake is used this would need to be fitted with a switch to "Stop" the VFD when it is activate.

CS

The problem I have encountered with a VFD on a Student lathe relates to the flat belt drive on my model. I suspect that this was a major reason for the change to multi-V belts. If you set the turn-on speed control too quick, the belt is likely to come off, and ditto if you try to stop suddenly. The stop works OK, but then you have to clamber about refitting the belt. So if anyone has a spare set of V pulleys, do get in touch...

Another effect to be aware of is that the flat belt runs on 'crowned' pulleys. (The rubbing surface is flat across in the middle of the pulley face, and gradually chamfered off at the edges.) This keeps the belt on, and with the original set up works OK, as the motor is always whizzing round. With a VFD, there is a temptation, when you want the work to turn very slowly (checking for concentricity with a dial gauge, perhaps) to just turn the speed knob down, as you don't need power, just movement. This can bring the belt off, as the amount of crowning needed to work properly (as I have now discovered) goes up, as the speed goes down. Not really a problem, once you know it might happen, as the gearbox is a pleasure to use. Clonk click every trip, as you might say.

Cheers, Tim

And a PS about the original braking lever. As originally wired, the brake lever (about level with your left trouser pocket) turns the power off when the brake is applied. I left this switch in use for the control-power in the VFD, so it still works as intended (but most of the rest of the complex switching and wiring was removed. Especially the sneaky switch in a right-hand rear drawer which was closed by a lock and only Sir had a key ...).

Edited By Tim Stevens on 05/06/2023 18:16:21