Internal Power fuse blown on conformally coated boards

DCS (Distributed Control Systems) Honeywell
1

FSC I/O modules with fault message “Internal power-down”. What will be the reason

2

Mostly it is caused by a combination of two factors:

  1. The Safety system has degraded performance caused by Electromagnetic Interference (EMI) entering the system via the field wiring and/or power distribution cables.
  2. Conformal coating on I/O module affects the functionality of the fuse in the Internal Power circuit.