A C208 STBY PWR ON caution alerted while at cruise accompanied by popped circuit breakers. Shortly thereafter the cockpit filled with smoke so the pilot declared an emergency and landed at nearby airport.

Narrative

I was flying a repositioning leg. I was flying at 5;000 FT in IMC when my STBY PWR ON caution light came on (GEN FAILURE and STBY ELEC PWR OFF warning/caution lights did not illuminate). Since I was in cruise and was being vectored around for the ILS 22L; I knew I had the time to try and diagnose any problem I might have. So I got out the emergency checklist only to find out that there is not a checklist for this specific situation. Looking at my generator; the amps showed around 50 (keep in mind I had just received a trace of rime ice; so all my de-ice systems were on); while my alternator amps showed around 30. Knowing there had to be reason for the caution light; I decided to test my alternator to see if it would take the entire electrical load (as it did successfully in my Before Takeoff checklist). I proceeded to monitor my alternator amps and tripped my generator offline. The alternator took the load and rose to about 50 AMPS. I then reset my generator to see if the generator would take the load and extinguish the light. However; the STBY PWR ON caution light remained illuminated. Since I had proven my alternator was working; I reduced my electrical load further down to about 30 AMPS to keep a healthy margin below the alternator's 75 AMP maximum. It was also at this time that I noticed that two circuit breakers had tripped; both being BUS 2 PWR circuit breakers (I found out there was more when I got on the ground). As I reached for my emergency checklist to see what it might say about BUS circuit breakers tripping; I saw; out of the corner of my eye; another circuit breaker tripping (turned out to be the STBY PWR circuit breaker) and some light smoke rising out of the circuit breaker panel coming toward me. As a result; I immediately donned my oxygen mask and declared an emergency with ATC. Approach responded by giving me vectors to a nearby airport and descent down to 2;000 FT. As I looked to my right to find the airport; I also noticed some of my engine gauges had stopped working since I had seen the smoke. The failed gauges were: Torque gauge; ITT gauge; fuel flow gauge; and right fuel quantity indicator. Leveling off at 2;000 and a heading of 130 (it was an emergency descent at 165-170 KTS); I was given a new heading of 170 for the airport and I saw it shortly thereafter. I then proceeded to land without incident. There was smoke in the cockpit. Therefore; I declared an emergency and landed the plane at the nearest suitable airport.