Wiring of control box for VFD help - included rev1 design

[SteveATL]

I purchased a Avid CNC (waiting for delivery), but decided to do my own electronics since I wanted things different than what they offered (water cooled spindle, etc).

So, I am starting with the VFD box and need some assistance to make sure I don't blow anything up (or myself)...

The design (included) is based off of 240 (30 amp) single phase power (L6-30P connector).

Can anyone give me any advice or changes to this design?

Here is a link to the PDF design http://aXsInfoSupport.com/SpindleBox.pdf

Thank You,

Steve

[SteveATL]

I have a PDF file, but the forum will not allow it due to it's size (99kb)

[mactec54]

I purchased a Avid CNC (waiting for delivery), but decided to do my own electronics since I wanted things different than what they offered (water cooled spindle, etc).

So, I am starting with the VFD box and need some assistance to make sure I don't blow anything up (or myself)...

The design (included) is based off of 240 (30 amp) single phase power (L6-30P connector).

Can anyone give me any advice or changes to this design?

Here is a link to the PDF design http://aXsInfoSupport.com/SpindleBox.pdf

Thank You,

Steve

That looks good, but your 15A is not going to be enough, you will need a minimum of 25A for single Phase supply for a 2.2Kw spindle, you also have to run the rest of your machine from this same supply so will need a Neutral and a 4 pin plug if you need 120v supply for the rest of your machine

You also don't need those Fuse's as you have a Breaker and the Estop would be a question also normally and Estop would be turning off the VFD Drive Fault circuit or a Contactor

Hitting an Estop cutting Power to a High speed spindle is going to kill the VFD Drive

[Al_The_Man]

NFPA79 states you need to remove all motive power in case of an E-stop. Fitting a e-stop contactor on the input can still follow regs by installing a "controlled stop" , fortunately NFPA allows you to read the motor stop condition before removing the power, (controlled stop) in this case you will not experience any problem.

It can be done by setting one of the VFD outputs to 'At Zero Speed' in order to keep the VFD contactor in until zero speed, this allows the required delay before operating the VFD E-stop contactor.
The normal instant e-stop relay would first operate the stop PLC input on the VFD, it sounds a little complicated, but simple once you work on it.
As a CNC retro-fitter, I am obliged to follow the rules and observe safety, and this works well for me!
Al.

[mactec54]

NFPA79 states you need to remove all motive power in case of an E-stop. Fitting a e-stop contactor on the input can still follow regs by installing a "controlled stop" , fortunately NFPA allows you to read the motor stop condition before removing the power, (controlled stop) in this case you will not experience any problem.

It can be done by setting one of the VFD outputs to 'At Zero Speed' in order to keep the VFD contactor in until zero speed, this allows the required delay before operating the VFD E-stop contactor.
The normal instant e-stop relay would first operate the stop PLC input on the VFD, it sounds a little complicated, but simple once you work on it.
As a CNC retro-fitter, I am obliged to follow the rules and observe safety, and this works well for me!
Al.

You have to consider with your industrial experience there systems are not turning off these high speed spindles and are also operating with 3Ph power and most machine would have a Breaking Resistor to prevent any problems of a mains power cut so in your case this is a normal install

So correct to a point, but it can't be used like he has it, or the VFD Drive would be damaged, if he hit the Estop the way he has it and the spindle was up to speed ( 24,000 RPM ) the VFD Drive will be instantly fried, it will take out the IGBT's every time

So Estops for this type of install have to be configured so the main supply power is not remove until the spindle has stopped

So enough of what the industrial builds require, and show a better solution for a Single Phase Build that have more hurdles than any industrial system to over come, they don't compare to a Single Phase Hobby Build

[Al_The_Man]

You have to consider with your industrial experience there systems are not turning off these high speed spindles and are also operating with 3Ph power and most machine would have a Breaking
So Estops for this type of install have to be configured so the main supply power is not remove until the spindle has stopped

So enough of what the industrial builds require, and show a better solution for a Single Phase Build that have more hurdles than any industrial system to over come, they don't compare to a Single Phase Hobby Build

That is exactly what I posted, it is a very simple way to conform to safety requirements and also cause no stress or damage to the VFD.
If the OP needs it, I can post an example schematic.
Every system, whether amateur or professional should have a legitimate E-stop circuit.

[mactec54]

That is exactly what I posted, it is a very simple way to conform to safety requirements and also cause no stress or damage to the VFD.
If the OP needs it, I can post an example schematic.
Every system, whether amateur or professional should have a legitimate E-stop circuit.

Implementing it is another thing everyone should be using a Safety Relay in the Estop circuit this is the best way to do it, the biggest problem is to get the motor stopped before the mains disconnect which is not so easy with some of these cheap VFD Drives

[Al_The_Man]

I already posted a method that works, the VFD contactor will not drop out after an E-Stop has occurred until the At Zero Speed output in the VFD is activated or already at zero speed..!

[mactec54]

I already posted a method that works, the VFD contactor will not drop out after an E-Stop has occurred until the At Zero Speed output in the VFD is activated or already at zero speed..!

We look forward to seeing a wiring diagram and what Parameters to set with a working video this would be the only way to get this into the Hobby user's hands talking about it is pointless, don't forget you need a Reset circuit also

Zero Speed output is pointless as the Damage is already done by the time it Stops

So this in essence is still a problem as most SMPS and the Spindle will take more than 10s to stop after an Estop the damage is already done

So just using a normal Estop circuit will do the same job just by using the control circuit terminals which can use an Estop input ( 09 can be used for this) and does a good job, this leaves the VFD Drive disabled, it can not start until a Reset has be done from the control or with a Reset Button

This is similar to what you are doing but no Zero wait before disconnect

[Al_The_Man]

My method is when an E-stop is issued, a stop is commanded to the VFD If the VFD is already at zero, the disconnect contactor is activated, IF the VFD is in run, it waits for the motor to be at zero before disconnect.
This method satisfies your concern about removing the power when the VFD is running, this also conforms to NFPA79 category 1 E-Stop, i.e. A controlled stop, removal of power when machine devices have stopped where damage can occur to machine if power is removed immediately.

So just using a normal Estop circuit will do the same job just by using the control circuit terminals which can use an Estop input ( 09 can be used for this)

Unfortunately this does not satisfy safety regulations as it applies to an Emergency stop, where it is stated that "removal of the device power shall be achieved"

.This reveals an issue that occurs with forums such as this that deal with assistance and advice to those that often have no formal training in the subject matter and where strict guide lines have been laid out generally for safety reasons.
I feel it is incumbent of any advice I offer to fall within those guide lines and then it is up to the recipient of the advice as to whether he accepts it or not.

[mactec54]

My method is when an E-stop is issued, a stop is commanded to the VFD If the VFD is already at zero, the disconnect contactor is activated, IF the VFD is in run, it waits for the motor to be at zero before disconnect.
This method satisfies your concern about removing the power when the VFD is running, this also conforms to NFPA79 category 1 E-Stop, i.e. A controlled stop, removal of power when machine devices have stopped where damage can occur to machine if power is removed immediately.



Unfortunately this does not satisfy safety regulations as it applies to an Emergency stop, where it is stated that "removal of the device power shall be achieved"

.This reveals an issue that occurs with forums such as this that deal with assistance and advice to those that often have no formal training in the subject matter and where strict guide lines have been laid out generally for safety reasons.
I feel it is incumbent of any advice I offer to fall within those guide lines and then it is up to the recipient of the advice as to whether he accepts it or not.

I agree with what you are saying which is in this case to comply with Electrical safety regulations

Most don't have an electrical safety problem and don't need total electrical isolation, so lets call it a Red Button

What is the real use of an Estop for any machine, all machines have different requirements

This is not an electrical Safety issue it's just a way to stop the machine, you can have a Red Stop Button which can do the job, Most Machine manufactures use / have a Red Stop Button that stops all machine movement instantly this does not shut down the whole Electrical system this is all most Hobby users need to stop there machine

Removing complete power to the whole machine can cause serious electrical problems, you can safely remove power that is needed for a normal Stop with a Red Button without a complete disconnect and still be compliant

An Estop circuit is for total Electrical Isolation next to a Disconnect Switch which all machines should have

So we may have been calling it by the wrong name, so lets just call it a Red Button that stops machine movement when you think you are going to have a crash

Anyone can still have a Estop circuit to be compliant with Electrical Codes just incorporate a Red Stop Button as well to stop when you need to

[Al_The_Man]

Sample:

[Al_The_Man]

Here is an NFPA79 showing an E-stop circuit that has been around for many decades and has been a standard feature of just about all the machines I have worked on since the late '50's.
I am surprised that N.A. has not adopted the Safety Relay as a standard to replace this old method, they are common in European machinery, and in some cases, mandatory.