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  1. S

    Sequential reversing starter for metal detector conveyor

    I have been told using VSD in close proximity with metal detector is not advisable, due to interference. Don't know if multi-frequency ones are more immune. 300kHz operarating frequency might too close to VSD PWM range. The main culprit in this case is old and dirty conveyor belt with rust marks...
  2. S

    Sequential reversing starter for metal detector conveyor

    According to some other sources only LC1D09BD has integrated back EMF suppression, hence the confusion.
  3. S

    Sequential reversing starter for metal detector conveyor

    It's a private project built form scratch and there isn't any edible matter in vicinity. Connected some freewheeling diode across the coil, although it says that it already has built-in bidirectional peak limiting diode suppressor...
  4. S

    Sequential reversing starter for metal detector conveyor

    Probably will have to add some capacitor for short duration ride-through since it's a 24V DC contactor. Since there are mechanical interlocks in place there might not be any negative effect on reversing starter due to prolonged dropout times. Another option would be to use timer with solid state...
  5. S

    Sequential reversing starter for metal detector conveyor

    Well, the first thing that needs to be sorted out is intermittent stopping of a forward contactor due to change-over between COM and NO/NC contacts on splice nullifier timer relay. It happens even when the time delay is set on longer than 3 seconds which is long enough to override the rejection...
  6. S

    Sequential reversing starter for metal detector conveyor

    Can't seem to find any standard circuit diagrams for sequential reversing starter. The metal detector conveyor has manual mode and automatic reversal mode. Need to prevent the conveyor from going backwards during false signals or anything else while the conveyor is standstill. It should reverse...
  7. S

    Melted cable spiral wrap

    There is something which looks like 4mm or 2.5mm on the supply side between the isolator and 63 Amp MCB and contactors. Haven't seen spiroband being used on power circuits before.
  8. S

    Melted cable spiral wrap

    There is one but it's dysfunctional, not the first time when coming across oversized overloads. Have seen a lot of machinery with oversized overloads over the years for some odd reason. I'm afraid intelligibility of the picture will be insufficient as everything has been squeezed into smallest...
  9. S

    Melted cable spiral wrap

    As far as I know particular installation has been carried out by senior electrician. Might have just run out of materials and decided to use what's at hand so everything's understandable. Seems like fairly light loading has been taken into account as well, hence the use of undersized conductors...
  10. S

    Melted cable spiral wrap

    That might do the trick.
  11. S

    Melted cable spiral wrap

    Haven't seen anything like this before. Star-delta starter for a 30 kW motor has been entirely wired up using conductors (looks like 2.5-4 mm2, 3.5 mm external diameter) cut out from sy cable and the like and wrapped with spiral wrap which has melted. Motor current mostly stays around 20 to 30...
  12. S

    NO switch insulation resistance failure

    Early lexicographers made little attempt to match spellings, hence homophones.
  13. S

    NO switch insulation resistance failure

    It just was one of those cases when by fixing something else next thing brakes down, that was the reason for confusion. Although the particular culprit was on a completely separate circuit within the machine lacking any wiring diagrams or anything.
  14. S

    NO switch insulation resistance failure

    Inductive load in the form of contactor coil.
  15. S

    NO switch insulation resistance failure

    Another reason why using low voltage ohmmeter alone during troubleshooting is never enough. By using the most basic logic this kind of fault should be resolved in the matter of few minutes. I wonder how often this kind of fault develops on more dangerous machinery. Couldn't find anything...
  16. S

    NO switch insulation resistance failure

    Don't know the exact voltage this time but sometimes 24 V is enough.
  17. S

    NO switch insulation resistance failure

    When the voltage is high enough some leakage current develops between the terminals.
  18. S

    NO switch insulation resistance failure

    No, from a real world experience.
  19. S

    NO switch insulation resistance failure

    How often do we usually have insulation resistance failures on an NO switches leading to unexpected starts?
  20. S

    Electric shocks from a light switch in the kitchen due to humidity, condensation

    The only fact I know is that there was prolonged cooking of a dinner going on, which has caused abnormal levels of humidity.

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