let me clear this digital speed governor simply is a digital control panel with integrated voltage regulator, this panel used to control and regulate the output of the turbine or generator.
To suggest a good hint one has to look for more things, but I can give some points to think, supposing the equipment has a special meaning for the user and it is worth a investment:
1. If the risk is within the pannel and you want to prevent damage on it on a early response basis: think of locating a smoke sensor in it or a more complicated detection system like VESDA (look f this on the webb). Sometimes you can buy the equipment with a smoke sensor in it or asking for premission of the manufacturer to install one or a VESDA system. A detection system would be good only if you can provide an effective response to shut down the power or extinguish the fire.
2. If the risk is outside the pannel and the place is closed, think of an clean agent system for the room.
3. Locate a smoke sensor above the pannel.
4. Look for specific requirement on an NFPA specific for the facility or FM standard.