Retrofit Precix 3 Axis Gantry Mill

Re. the Einschaltstrombegrenzer -- You can talk to me in german too (probably better in the german subforum) as I'm a fellow austrian.

The magnetic flux in the transformer will try to keep any current flowing while it is collapsing, and can generate more or less unlimited voltages, so turning off inductive loads with SSRs that are not designed to do that can be problematic -- the stored energy in the magnetic field needs to be dumped somewhere.

The tripping of multiple breakers in a row is really suspicious. A B-type breaker takes at least 3-times the rated current for the magnetic disconnect, so 48A. To limit current, you could wire a light-bulb (100W incandescant) in series to the transformer, but I'm not sure if it will survive the shut-off surge so take care. Can you upload your schematics? Maybe the SSR really is the problem even when turning off. Try using a contactor ("Schütz") or for test purposes a manual switch or even bridge it.

Re. safety, maybe you can use a light-curtain ("Lichtgitter", ~500-1k€) in your e-stop loop (with "Schlüsselschalter" to bridge it) -- but those can be problematic if chips can disrupt the beams.

The Servo Power SSR was originally planned also to be controlled by LinuxCNC E-Stop. But as this inductive problems came up i thought maybe leave the toroid on for E-Stop cycles.
The big caps would run the motors for quite some while in case of mosfet shorting out?
So you mean just to add the extreme/min switches to the E-stop. right?

Bin eigentlich "Steirer" living in vienna.
It worked before with ssr for ages, the B breakers trip also on other machines. i will do the schütz thingy for sure. The light bulb comes only when everything fails , but i am optimistic with the schütz. 
Added an image of old ssr/ntc and my scheme... thx 

 

Did a research on this, zero crossing is most common, random switching you hardly stumble upon. Checked mine are 0 crossing. Low chance the blown one was bad fabrication (Chinese)

Maybe that was already answered elsewhere:

* Did you check that really the toroidal transformer is the problem?
* For testing purposes try wiring in the light-bulb and look if it flashes when turning on/off

* crazy: are you sure you are turning off? maybe the SSR logic is inverted somewhere? if you don't run the motors on the test setup it may be possible to miss that...

I feel your SSR is rated for resistive load .So it fails with inductive load.
Use a Mecchanical Relay or find an SSR which can handle Inductive load.
The 1500w toroidal inductive load can create large spike during power off.
You need to arrest this.
Some SSR have build in snubber .
But your transformer is too big and spike can be larger than SSR rating .

From the schematic I believe circuit is with soft start.
I do not see any control for the NO contact shown across the P14 .
Does it has bult in timer ?. This must have an ON delay contact to avoid inrush current.

Refer below page on softstart for toroidal transformers.
sjostromaudio.com/pages/index.php/hifi-p...ansformers?showall=1
It uses two relays. The second relay will be switched on after a time delay

I would sugget use an Electro Mechanical Relay instead of SSR.

Attached a reference page from Omron's Technical guide

 I also attached some images and a schematic of my current controller setup.

Thx,
Armin

 

Please recheck this. The older componant marked as "SSR Relais" in the first post photo is an Electromagnetic Relay .

just checked,
you are right it is a mechanic relais thx. i labeled it wrong. but i was just for switching auxiliary devices (PC)