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Smart machine, dumb BOD

Former Community Member
Former Community Member
Well that was an interesting morning’s lesson:
Rule 1: Don’t believe what client tells you
Rule 2: Don’t believe vendor of equipment
Rule 3: Persist
Rule 4: Learn
Background: The Client has 10 kvA diesel generator with 110 V and 230 V 32A socket-outlets available without having a select voltage option so could use MIG welder and tidy up welds with grinderette. I made up months ago, a simple 32 A to 16 A 110 V extension lead to enable client to run the grinderette. Client complains that my lead now doesn’t work so go back and check and yes, it doesn’t work. Hmm, I&T lead, all ok. Have inspirational thought and make up a short 16 A to 32 A lead and plug this into workshop 110 V mains fed Tx and and my original lead. All working so my lead ok. Check output voltage of genny and 115 V so now very puzzled. Show client and he concludes his generator has gone faulty so takes it back to vendor as within warranty period. Genny returned with video showing genny powering up a drill and vendor questioning client's choice of electrician...... Client robustly suggests I check my lead again.
Can you tell what is wrong with the above situation yet?
I go back again today and make up two more leads and repeat above with same outcome.
Finally, the penny drops and the client must have changed brand of grinderette to a soft start/brushless type despite telling me he hadn’t. I decide to plug in another load, so I found discarded 500 W working Halogen lamp and that fired up. Vindication of my ability to wire up a plug!!! Ring vendor and after a fairly robust conversation eventually “remembers” that he’d had one user say the genny wouldn’t run a drill.
So, I tried the offending grinderette in a very basic 3 kVA petrol genny with my lead and all works, so definitely an incompatibility of “smart” tools with the diesel genny.
So, could I have done better? Yes, but I trusted the client’s statement it was working before. And should I have thought that the supposedly better genny would have generated a “pure” sine wave rather that what appears to be a “modified square wave”? I begin to wonder if the genny is really only wound 230 V with some sort of electronic device to make 110 V waveform. Out of my technical comfort zone there but all resolved by the client buying a “dumb” grinderette. On which note, I was told that new legislation for hand held grinders has come in this year requiring soft start on all new ones, but yet to confirm.


Regards


BOD

  • 0
    perspicacious:
    I was told that new legislation for hand held grinders has come in this year requiring soft start on all new ones, but yet to confirm.


    Same as kettles! Sorry, 17 days early! ?


  • 0
    The normal one I get is "No one has done any work in the house in the last few years".


    Then having spent ages fault finding and finding the nail through the cable under a floor board refitted by the plumber who had fixed a leak a few days ago, which they had forgotten about and just happened to coincide with the fault appearing.


    Or perhaps more popular and easier to find: "Oh I changed a light fitting a few days ago, I wired it up exactly the same".


    These days my fault finding normally starts with the Spanish inquisition

  • 0
    I presume the soft start requirement is to stop it twisting out of your hands when it starts up.
  • 0
    The waveforms on some of the newish fuel efficient gensets are awful - the motor can now run at an optimum  load dependant speed, as there is no need for constant speed for 50Hz - it is only generating a DC that gets sliced and diced to create an inverter waveform. Some are more or less like a a sinewave but the simper ones are really just a square wave with a dead time between polarity reversals, so the RMS and peak are right but nothing else is.


    LED lights with capacitor  droppers do not like them either...

    M.

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