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Thread: VFD Circuit Diagram Question
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22nd May 2014, 01:10 AM #61
He will - just not yet tonight....
Possibly not tomorrow either... however, I have set and tried both parameter options on my HY VFD separately (not on the combine circuit yet) and both work.
I intend to use the HY E-stop (Parameter option 13) as my 'normal' operational stop - coasting to a stop using a NO switch, and the HY Stop (Parameter option 04) as my 'Emergency' big red latching button - and possibly additional knee/foot/safety limit switches all in series - using NC switches ramping down and DC braking as fast and as hard as possible without tripping any overvoltage or overcurrent alarms. That way, as discussed, the machine will come to a rapid halt if any wire gets broken, connection corrodes, switch fails or limits are reached - or I confirm that the colour of adrenaline is brown in a tool crash!
Rather than as HY seems to have designed their e-stop - finding out a cable is broken by the machine NOT stopping in an emergency
But then maybe the 'e-stop' label is a 'glitch' in the translation and in Chinese it said something like 'Electronic lunchbreak pause Setting'.....Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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22nd May 2014, 09:54 AM #62Cba
- Join Date
- Aug 2007
- Location
- Melbourne
- Age
- 68
- Posts
- 1,410
Joe,
I have set up my lathes to use dynamic braking when the red mushroom is pressed. At the same time, I sometimes adapt the dynamic braking time depending on what chuck workpiece I currently use. With the small and light collet chuck, I can use braking times of down to 0.5 second and it will still reliably stop from 4000rpm maximum speed. But with a chuck and larger workpiece I may have to set this to about 3 or 4 seconds. If the braking time is set too short, the VFD "trips" and the spindle leisurely coasts to a halt.
Now the same happens when pressing the red mushroom. On the smaller lathe (1/2HP) I use a Siemens VFD and if the braking time is set too short, it will simply trip and coast to a halt. On the Hercus 260 I use a newer and more intelligent Yaskawa VFD. It can be set for an "optimum" braking time, where the VFD on the fly calculates the shortest possible decelleration without tripping, depending on the total inertia. That is a nice feature for an e-stop.
It is something to consider when deciding if the emergency stop shall cut the power to the VFD, or initiate a stop with dynamic braking. In my experience, if the VFD is chosen one or two sizes larger than the motor, the dynamic braking works much better on a machine with widely varying inertia like a lathe, where you can have different gear settings, different chuck weights and different workpiece weight all affecting inertia. This is not only theory, I currently run my smaller lathe with a smaller VFD than the motor (1/2HP VFD and 3/4HP motor). It is not an optimal choice because of the braking limitations, but I had to use whatever VFD bargain I had at hand at the time. Because it is a vector drive, it still performs better at low speed, than the 1HP non-vector VFD that I had before on this lathe. But if there is a choice, I would always recommend to choose the VFD larger than the motor.
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25th May 2014, 10:11 PM #63
When in Adelaide today, after a weekend family visit (missed our newest grandson's birthday plus my mom's birthday) I bought the parts I need (in multiples) from Jaycar.
I have a week off, so I will be able to do some work in the evenings, after some catch up farm work. I have designed a new housing for the VFD, made from particle board and 6mm plastic sheet designed to be used for electrical mounting purposes, which will be bigger, and have a filtration system using baffles on the back, and a foam filter element. An 80mm computer fan will provide air flow. The front panel (plastic) will be fixed, with all controls except for the main switch. This will be mounted on the original Lathe Control Panel. The back panels of the housing will be the access for the housing. The filtering baffles will be part of the rear opening back door. This will mean the wiring will not need to accommodate an opening door as with the current one. The air exhaust will be out the top, which will have a cap to prevent dust from settling on the fan. I will provide pictures as I build it.
This is the basic layout of the front panel.
Lathe VFD Housing Front Panel.jpg
The VFD will be mounted on the back of this panel, inside the housing. I have not decided whether to have an E Stop on this panel, as I will have one on the brake pedal, which will be the main off switch with manual braking.
More to come.
Dean
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