I work in a plant where standard procedure for LOTO is to knock down an entire power/control panel. When this is done, all associated PLCs and HMIs are de-energized as well. Any ideas on how to economically change this? My fear has already been realized. Sometimes when power is re-applied, I've lost programs or even modules. As background, my facility was state of the art oh 30-40 years ago. Safety PLCs don't exist here and only some equipment have safety relays.

 

>...Sometimes when power is re-applied,
>I've lost programs or even modules.

Least expensive solutions, to most ...
* Put power line filters on 120v control side before PLC power.
* Make backups of every PLC program, every 6 months whether you need to or not.
* Replace PLC battery every 3 years whether you need to or not.
* Rout 120v and PLC programming port to outside the panel
* Network all your plant PLCs to the engineering/maintenance office for easier backup and access without LOTO
* Have panels designed with DC PLC in external sub-panel

REF: http://bin95.blogspot.com/2014/02/control-panel-design-guide.html
REF: http://bin95.com/maintenance_management_plc.htm