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  1. #1
    Join Date
    Jul 2011

    Thumbs up FIRE!!Colchester 2000L Fanuc OT

    Turned the lathe on this evening for the 1st time in a while....

    Something caught fire ....

    What is this:

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  2. #2
    Join Date
    Oct 2009
    It looks like a resistance. I see a sensor that probably did not work. You should check the sensor (red and blue wires) to see if it is shorted.(short is ok).

  3. #3
    Join Date
    Jul 2011
    Ok, I will look tomorrow.

    This is the discarge unit? what would cause this to fail?

    The machine has been off for a few weeks and got moved and re wired, could incorrect wiring cause this??

    Many thanks, Dave

  4. #4
    Join Date
    Feb 2011
    too much voltage will do it. if transformer was changed, be sure primary taps are set high...

    the newer spindle (servo too- but they have internal dump resistors 90% of the time) drives have a single power transistor that switches a big resistor across the dc bus whenever excessive regeneration causes dc bus to exceed its normal range...a little too much input voltage causes the regen circuit to try to dissipate it- but it cant...they will usually be smoking within a second of power on, have seen them many times glow red hot. usually any damage gets limited to the 'q1' switching transistor, but it only happens if they are left on for some seconds. usually smoke gets them shut off in a panic before permanent damage.

    another possible cause- if you have a big power correction capacitor bank in your sub, be sure the VAR controller is functioning correctly- twice over the past 20 yrs someone put our VAR controller into manual to test the contactors, and left it on, caused a leading power factor during low load times (Edison hates that too) our 480 shot to 515 over the lightly loaded weekends, both times we had a mess of drive transistors to replace. its not just small shops have this trouble- we buiilt some lathes for a aerospace manufacturer, got a warranty call the first weekend we left -same situation...went up on the roof with their maintenance guys(sure seemed a odd place for a cap bank, but nice setup!), sure enough their VAR controller was in manual, power factor meter was showing lead... here they had been having weekend drive failures intermittently for a year, one guy said they had replaced the controller about the same timeframe...surprised the utility hadnt come down hard on them for pushing voltage.

    while we have had a few Q1s short for unknown reasons, the biggest causes have always been a new guy moving a machine, tapping the new isolation transformer for 'proper' 480 instead of the seemingly improper 510. fanucs like 210-220 all the ones weve had switched into regen right at 242 or above
    dont know what service you are on, or what drives are there, but I'd watch that the voltage isnt a little higher than before you moved it. some installations use a 208Y/120 secondary, nice safe voltage, but I was told y types can cause other issues...I was told long ago that a wye secondary could cause 'ferroresonance' (still remember the word, never looked it up) in certain ground fault situations, and 240 delta secondary gives better isolation from ground faults elsewhere, but the 240 can be risky...all ours have 5% primary taps, we just tap them too high to drop the secondary... we had ONE machine with a wye secondary transformer many yrs back- biggest machine in the shop, Kitako 4 spindle/8 axis lathe...lightning hit our sub one night, other than fuses the shop fared well- but they actually scrapped the kitako, had 2 6t-c controllers, 8 m series servo drives and 2 dc spindle drives- every power component in those was blown, never saw such damage before or since, threw away any wye transformers that came in since too

    anyways, good luck, hopefully no other damage

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