We are facing an issue in our protection circuitry. For the below DC design MOV between Earth is getting damaged in the site.
MOV 2 & MOV 3 in the circuit is failing in the site.
System is powered from UPS with Centre point earthed.
MOV is having a continuous DC voltage of 380V & Spark-over voltage of GDT is 230V/s & Break-over voltage 450V/Us.
We have also one more design with GDT connected in series with MOV2 & MOV3 to Earth & This design has no MOV damage issues.
So my Doubt is :
What could be the reason of MOV failure in the circuit without GDT protection. ?
Whether GDT is blocking the high Impulse voltage so that MOV is safe without failure?
MOV used - 14D471K from bourns