Gallery, Projects and General > The Design Shop
Microwave owen transformer spot welder?
PekkaNF:
--- Quote from: PekkaNF on January 11, 2016, 02:45:42 PM ---OK. ordered one hal conraption that might get me somewhere on current measurements, this type, but different shop:
http://www.amazon.com/Hantek%C2%AE-Current-Clamp-kHz-20mA/dp/B00BLD6FB8
It's on the mail...I have palyed with hal clamps and transducers before...not having utmost trust on that one, but it IS isolated!...
--- End quote ---
Got it some time ago and it works! Pretty close on sine wave and it does shows if there are any triaks on the line.
I'm been reading and shifting some info on "floating" measuement and it still is as it used to be before: Needs very carefull concideration. Next measurement is going to be scope grounded, but DUT floating. Basically I'm grounding the DUT fairly close to return path anyway, therefore I should be able to to measure it without blowing anything up and measurement should be safe too. Now I can put my 100:1 probe on good use.
I actually might still try to build isolated differential amplifier, but there are some steps I'm not too confident with, like SMD and making circuit boards.
Pekka
PekkaNF:
Put those probes into some use.
Probes were 1:100 passive probe and HAL current clamp.
My friend has a problem: He has a ceramic oven he plans to use for hardening and tempering. The thing is someone "rigged" it for sale: Heater resistors are 110V + big transformer 110/230VAC, broken temperature sensor and controller that does not belong to it.
Cunning plan is to use main contactor that feeds the tranny and then put SSR between tranny and resistor. Good thing that a little hysteris will not kill the main contactor, bad thing is that SSR needs twice the current rating on secondary.
But I need to test the concept. I had 15A zero crossing SSR that is too small for the job, but just fine for a quick and dirty test: isolation transformer, secondary on float. SSR between secondary and 200W load resistor. Secondary nulled where comfortable for voltage scope ref (ground) and current clamp allows current measurement at will.
1. even with zero crossing, there are 32v "spikes" over the SSR, nothing to worry.
2. current and voltage wave form is nice into resistive load
3. zero crossing switching ON!
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