Retrofit Precix 3 Axis Gantry Mill

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 

 

From memory, AC SSR should only switch on at zero crossing, otherwise they blow up.
Not sure if they also switch off at zero crossing, though?

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)

Chinese SSR if it says 40A, probably 10-15A is OK, above it they usually blow up. Plenty of videos on youtube about exactly that.
Get an Omron one, original if possible!

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