Replace Internal PRT-E1500W With External - Can It Be Done?

[TaffyCarl]

Hi,

Last thought before I buy a new machine. Seeing as I can't gain access to the VFD's settings I'm going to call it "stuffed" - a replacement is $150 AUD plus postage from China. After watching numerous youtube videos on wiring VFD's up I had a thought that I may be able to use an external VFD and the PRT-E1500W box just as a controller for the X, Y and Z using Mach3 of course.

1) Is this at all possible?
2) Have I missed anything?
3) Am I wasting my time?

In the photo of the internals of my box I've circled the wires that would need to be attached to the external VFD. the other photo is the VFD I'm looking at.

Cheers

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[john-100]

if the breakout board is like this TX14175



I don't see why not

the BOB will have a 0-10V analogue output to connect to the new VFD to control the spindle speed
and a relay to switch the spindle on and off

John

[Sterob]

Probably just as easy to remove the old VFD from the enclosure and fit the new VFD in its place.
Would be alot neater.

[john-100]

While fitting the VFD inside the control box is neater
having the VFD external can reduce the electrical noise from the VFD and its wiring
from interfering with the low level logic signals from the BOB


many of the Chinese CNC control boxes have a shock hazard due to the use of a 5 pin plug as the outlet to the spindle motor



I would either fit a socket on the box or use a strain relief and connect the motors cable directly to the VFD terminals


also double check the earth wire is connected to the spindle motors case
very often the 4 pin plug on the motor does not have the 4th pin connected !



John

[TaffyCarl]

While fitting the VFD inside the control box is neater
having the VFD external can reduce the electrical noise from the VFD and its wiring
from interfering with the low level logic signals from the BOB


many of the Chinese CNC control boxes have a shock hazard due to the use of a 5 pin plug as the outlet to the spindle motor



I would either fit a socket on the box or use a strain relief and connect the motors cable directly to the VFD terminals


also double check the earth wire is connected to the spindle motors case
very often the 4 pin plug on the motor does not have the 4th pin connected !



John

John,

On the spindle connection inside the box, even though there are 5 pins only three are used. as for the BOB you show, it is like that.
You've lost me when you mention 'strain relief' (total noob to all this)

Cheers.

[Sterob]

While fitting the VFD inside the control box is neater
having the VFD external can reduce the electrical noise from the VFD and its wiring
from interfering with the low level logic signals from the BOBJohn

Agreed. Its a bit catch 22. Electrical noise varies with each VFD. Some are better than others. It certainly may be easier to combat it with the VFD on the outside of the enclosure.
I was thinking more about safety and neatness of the installation.

also double check the earth wire is connected to the spindle motors case
very often the 4 pin plug on the motor does not have the 4th pin connected ! John

John[/QUOTE]

Yes, he will find the earth connection missing, probably....
Very important if something goes wrong....

Steve

[ericks]

I also agree, if he can he should place his drive in a separate enclosure. However having these drives mounted in the open is a bad idea, i have seen people doing it

[john-100]

Hi TaffyCarl

If you did away with the chassis mounted plug and inline socket on the motor cable

you could use a cable strain relief / gland like this -



it protects , seals and clamps the cable as it passes through the cnc control enclosure
the spiral on the end restricts how much the cable bends as it exits the gland

from another post on cnczone a photo of limit switch cables passing through cable glands


an initial wiring diagram for a similar cnc machine



I noticed the crossed 2 wires on the Z axis motor to reverse the direction of the motor so it works with the default mach 3 settings !

down the right hand side is the spindle motor wiring

I suspect they use the cheapest cable available so the wire colours are not consistent from one machine to another
or internal wiring to external cable

NOTE the novel use of the yellow / green for the VFD V phase to the motor !!!


John

[TaffyCarl]

Cheers Gent's all info is greatly appreciated.
After watching numerous Youtube videos (such as the video below). What annoyed me was no real On/Off switch it has to be done at the wall hence my thought of sending main and spindle power through and using the On/Off switch of the semi gutted PRT-E1500W box. I suppose I could do it as most have done and flick the power off at the wall but to me that's an annoyance and untidy.
I made the jump from an air cooled 3040 which never missed a beat in years of use, to this water cooled 6040 in November 2018 and not used it once because of the faulty box and the fact the seller, and Paypal are d**ks.
I don't claim to be an electrical wizard, I've been stalling on re-wiring my 1966 Triumph Tiger even though I bought a complete new wiring harness and a workshop manual :-O so bare with me if I come back and ask more (simple?) questions in regards to this VFD setup.

Cheers again
Taff

[john-100]

if your CNC control box is like this -



your IEC mains input connector is connected to a 2 pole switch (with red neon indicator) that switches the mains supply to the VFD and the stepper drivers power supply



it looks like they have used 2 red wires to connect the live and neutral supply to the switch
and used 2 black wires to connect the switched the live and neutral to the VFD and stepper driver power supply



John

[TaffyCarl]

As a test I ripped the VFD out of the box, isolated any possible live wires, plugged it in and it didn't go bang (bonus for me) but now have no ability to move X, Y or Z via the keyboard or pendant, only via the tab out on Mach3 screen. I can't understand why it doesn't work on the pendant as the E-Stop, spindle speed etc do so it's not the pendant - hmmm odd.

Update:
Sorted, Jog was off, turned it on and both the keyboard and pendant now work. The X needed reversing but that's an easy fix - just need to fine tune the set up (moves to slow) when I get the VFD and spindle sorted over the weekend and start attacking scrap board to make sure everything's right.

[Sterob]

Good stuff..Your on to it.

[TaffyCarl]

Ok, the insanity sets in! The VFD turned up today, first set up made the controller box make some weird clicking noises so I scrapped that idea and just connected a power lead direct to the VFD as per the many videos out there. I set the basics to the required 400 and nothing went bang when I turned it on.

Took the top off the spindle and added the earth as recommended as each time I tried to get it going it gave me an ERR1 which the manual claims is a Short Circuit/Current Overload/Power Module Protection - to that I say "HUH?"

Took the cable out of the spindle and I don't get the ERR1. Am I looking at a damaged spindle or what? I've swapped the UVW connections around but nothing makes a difference. Attached is supposedly the manual for the VFD - nothing came with this AT1 so I had to hunt it down - just waiting on the seller to see if they have one but not holding my breath.

Cheers

[Sterob]

Damaged Spindle?.......maybe.
Got a Multimeter? Measure the resistance between all 3 phases on the spindle. They all should quite low and similar. ( not sure how low. )
Measure between each phase to earth. They all should be open circuit.
Not the 'best' way to test motors, but it should give you some clues. One really needs an Insulation Tester to get definitive results.....
If you DVM results are 'iffy', then testing with a Insulation Tester will be needed to confirm.

[john-100]

if you have wired it as in the manual


you can either have a stray strand of wire on a connector shorting a phase to ground
or the motor has been damaged and the insulation of one or more windings fails when the VFD is powered

an ordinary multimeter set to ohms will test at too low a voltage

insulation testers will test the insulation at 250 or 500V

John

PS

the phase to phase resistance for a delta connected motor is around 1.5 to 2 ohms

[TaffyCarl]

All that are connected are the LNE and UVW connections via spade connectors, not bothered with externals yet - same as the video I posted @ around the the 2.30min mark, the only difference being the ground on this VFD is on the opposite end of the connections to his. Essentially all I was attempting to do was to verify I had the VFD set up properly (p00x etc etc) before getting too carried away which from what I can see are correct, so it is leaning toward a fried spindle and if that's the case I can see the missus not being terribly impressed.

[john-100]

double checking

did you get the spindle to run without the ERR1 before you added the earth link to the motor case ?
have you had a close look at the added earth connections

john

[TaffyCarl]

No, I tested it prior to adding the spindle earth which when I got the ERR1 reminded me I didn't earth it, so I broke it down and added the earth. I've checked all known earth connections and they all look fine to me.

[john-100]

I have no experiance of setting up VFD's

to me you either have a faulty spindle motor or the VFD is set up wrong
since the ERR1 clears with the motor unplugged

John

[ericks]

Sterob gave you the correct/good advise....