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  1. Paulusgnome

    208V unit on 240V power supply

    According to the datasheet for that cooker, as downloaded from the manufacturer's website, it will operate between 200V and 240V. Link
  2. Paulusgnome

    Why do induction cooktops require ferromagnetic cookware?

    Thanks for the help. I should have done some basic research before posting.[blush] The wikipedia articles referenced be GroovyGuy above, and the article on induction heating are most helpful. Induction cooktops require ferromagnetic cookpots because they rely on a combination of eddy-current and...
  3. Paulusgnome

    Why do induction cooktops require ferromagnetic cookware?

    As I understand it, if I heat a piece of brass or aluminium by placing it inside the coil of one of my royer oscillators, the field is inducing eddy currents in the brass which is then generating heat through resistive heating. The brass piece is acting exactly like a shorted single-turn...
  4. Paulusgnome

    Why do induction cooktops require ferromagnetic cookware?

    I am playing around with induction heating at present. I have a couple of Chinese-built royer oscillator drivers, one good for ~100W and its big brother (~1000W). Both of these will easily heat steel, stainless steel, copper, aluminium, lead, the 1000W driver even comes with a carbon crucible...
  5. Paulusgnome

    Temperature controller with multiple analog inputs

    Eurotherm are a well-respected company with a great range of PID controllers. We have used them successfully for many years. They tend to be fully-featured and more expensive than some brands.
  6. Paulusgnome

    Temperature controller and temperature sensor compatibility

    I would use a PT100 sensor. They are cheap, accurate, and in many applications they are the preferred sensor type. NTC sensors are OK but can give accuracy issues, particularly if the length of cable between sensor and controller is long. Thermocouples are great for higher-temperature...
  7. Paulusgnome

    Production Line Electrical Testing

    Thanks, I was looking in the first instance for something off the shelf. Yes, I could cook something up, but who would do that if there was something already available? I have now found several options, and am sifting through them to find the best bang for buck. Best options at present appear...
  8. Paulusgnome

    Production Line Electrical Testing

    Hi, I am building a new production line for the small electric heating factory that employs me. This is a multi-station line where the heat pads are moved between stations as they are assembled, by a PLC control system. The end station is a vacuum press where the heat pads are pressed, load...
  9. Paulusgnome

    Thermal Fuse for panel heater

    Yes you can use a 10A thermal fuse in place of the 4A. It is the temperature rating that is critical.
  10. Paulusgnome

    Thermal Fuse for panel heater

    Thermal fuses are quite readily available. Here in New Zealand, I can get them from RS Components, Element14, and even the local Jaycar store. Do not be tempted to up-rate the temperature rating of the thermal fuse, it has been chosen carefully by the manufacturer to limit the chance of the...
  11. Paulusgnome

    Coordination Study for PLC Panel

    I find with this question, that it is best to use one of the circuit-breaker trip-curve plotting apps that the various manufacturers have on offer. I am currently using an application 'Curve Direct' from Schneider Electric, but have used similar software from GE and AB which gives the same...
  12. Paulusgnome

    simple comm system using visible light link

    Did this myself just over 40 years ago for a high school science project. Back then, LEDs were fairly new and something of an unknown quantity. We started with a simple incandescent torch lamp as the emitter, and one of the old-type germanium transistors with the painted glass envelope scraped...
  13. Paulusgnome

    What kind of load is a led drives?

    With devices such as LED drivers, the issue is not so much the displacement PF which as we have seen is a charming 0.95. The issue, if there is one, is the distortion introduced by the driver only drawing current at the peaks of the ac wave. So the answer is resistive, but decidedly non-linear.
  14. Paulusgnome

    Need Help! Modicon M340 w/Unity Pro XL v10

    Oops, I fear I spoke too hastily. That bit index doesn't work, does it? Sorry about that. I fear that you will have to write yourself a wee function block to do this. Translate your DINT into an array of bits which you will be able to index.
  15. Paulusgnome

    short circuit capacity of MCB

    The MCB should be selected so that its KA rating is at least equal, and preferably higher than the (calculated or measured) prospective short-circuit fault current (PSSC) of the supply. Industrial installations tend to have power supplies with high PSSC, hence the need for higher-rated circuit...
  16. Paulusgnome

    Need Help! Modicon M340 w/Unity Pro XL v10

    If you have defined UDT_Name as type WORD, then you can access the individual bits with an integer variable Step_Var by using UDT_Name.Step_Var and Unity should resolve this OK. Which is to say that it does in my code. I have arrays of words defined : Stationregs => ARRAY[1..3] of WORD, and...
  17. Paulusgnome

    RCCB burn out

    I note that while the RCCB is well broken, there doesn't seem to be a lot of heat distortion. The plastic case is still square and largely intact, but covered on black arc soot. This leads me to the thought that whatever did this, it was most likely a short-duration high-intensity event...
  18. Paulusgnome

    Multi-voltage switch sensing

    With a bit of thought I reckon I could come up with a reasonably simple electronic circuit to do this. I am assuming that you must want digital inputs ie 0 or 1, not to actually measure the voltage. I am thinking of a circuit that might use a couple of diodes connected in anti-parallel to cut...
  19. Paulusgnome

    Protection of ELV circuits

    It really does depend on the power supply in question. For instance, I use plenty of 240VAC/24VDC switchmode supplies in the machines that we build, and these all have built-in short-circuit and overload protection which operates far more quickly than a circuit breaker. If I were to attempt to...
  20. Paulusgnome

    Drawing program for system-level wiring diagrams?

    If your pockets are sufficiently deep, and your projects sufficiently complex, Eplan P8 is a good choice. We build automatic factory machinery here that bristles with servos, VFDs, hydraulics and pneumatics, and all of our electrical schematics are done in Eplan. It took me a while to get up to...

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