Re: Bridgeport Manual to CNC conversion...
K3 controls power to the servo drives, the N/C contact on the XPS monitors the K3 unit, if it is jammed or fails to open, the XPS does not pull in and Mach will stay in reset as well as no spindle relay/contactor supply.
If K3 jams on despite pressing the E-stop or limits, it will not latch-in again.
It was a reasonable safety enhancement i think.
As with all systems, a catastrophic failure - in this case K3 welding shut on one or more lines will still leave a danger but the chances of a contact weld at these low currents is pretty rare i think?
Re: Bridgeport Manual to CNC conversion...
You do realise that a standard contactor is designed so that if one contact welds shut, the others will still open?
Re: Bridgeport Manual to CNC conversion...
Interesting, would the carrier still lift the aux contact block though? On these Sirius range of contactors, the monitoring/feedback contacts are by way of an aux contact block mounted on top.
The XPS will not work without an N/C pair on one of the output channels.
Re: Bridgeport Manual to CNC conversion...
I never realised the XPS was through a NC contact.
It'll depend on the spec. Some will be designed so the contact closes regardless, others will hold it open. On larger contactors, you can normally wedge a small screwdriver in and close a single contact, which would then let you see if the NC contact opens or not, however smaller contactors are usually far more enclosed.
Having said that, at the currents you're working with, the contactor should never weld shut, so I wouldn't worry about it. Even if it was to stick and maintain full power, the power being maintained should not be the sole reason if the machine wasn't to stop during an e-stop.
Re: Bridgeport Manual to CNC conversion...
I just like having things covered as far as practically possible - in this case if the e-stop is pressed, the CSMIO is told to stop as well as power being removed from all servo's and VFD's, both via separate channels. I think that should be ok, the XPS contacts are forced apart so pretty much guaranteed to open.
BTW, what happens if a servo encoder fails - does the motor runaway or stop??
Re: Bridgeport Manual to CNC conversion...
On an AC/Brushless motor, the drive should detect a fault.
With a brushed DC motor, potentially run it into the limits at great speed.
Re: Bridgeport Manual to CNC conversion...
Quote:
Originally Posted by
Davek0974
BTW, what happens if a servo encoder fails - does the motor runaway or stop??
You need clean underpants - don't ask...........................
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Re: Bridgeport Manual to CNC conversion...
Got the panel finished, bench-tested, all passed 100% :)
Got the pendant rough-wired so i could bench-test the panel, seems functional.
All axes homed and jogged perfectly, no surprises, e-stop system seems to work ok.
Managed to lug the panel into the cabinet, nearly ruptured myself but it's in now and bolted down.
Tomorrow will be final wiring on the switches and limits etc, plus re-rigging the pendant for the next power-up test. Then I'll probably strip the pendant and send it out for powder-coating, or just spray it if impatience takes over ;)
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Re: Bridgeport Manual to CNC conversion...
Nice job Dave:encouragement:
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Re: Bridgeport Manual to CNC conversion...
Got the panel wired to the machine today, most of the big jobs done now, its running again, ready for testing.
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Small jobs to do like secure some of the cables when i work out where they need to be, make the belt covers, cover the Z axis drive, fit the light, then figure out how to run her ;)