Hi esteemed colleagues

I have replaced a 5kw Axpert inverter and it seems to have reacted with the alarm systems power supply...inverter is damaged. Is there a chance of resonance between inverter and alarm power supply

The short answer is no.  These power supplies are small and easy loads.

Home alarm systems normally use a conventional mains transformer with an output of 16VAC and rated for about 30 to 40W.  The alarm then has a simple rectifier circuit and a LM317 linear regulator to create the 13.85V float-charge voltage for a 12V 7Ah SLA battery.  Some better, or more modern, alarm panels might use a small switching buck regulator instead of the LM317.

It's odd that you would suspect the alarm PSU.  What gives you that suspicion?
 

My apologies... I was thinking on the lines of capacitors and perhaps inductors used in the power supply as prpbable ferro resonance sources. But thanks for the enlightenment... I puts my notion to rest.. Really appreciate this feedback. 

 

Ferro resonance one would worry about if you plug induction hobs or inverter welders and similar loads to the output of your inverter with thick, short cable.  Luckily an inverter installation (normally) sees many, many meters of house wire between itself and any serious inductive loads.  So the interconnect resistance should dampen the system.