SF340 flight crew reports generator failure descending out of FL230. Checklist is complied with and an emergency is declared; followed by an uneventful landing at destination.

Narrative

We were in cruise; level at FL230; when we were issued a descent to 17;000 FT. Just after that call was received; several things happened. First; I noticed that the Captain's EADI; EHSI; and the TCAS screens all went blank. I received a red 'FD' and 'Cross Side Data' flag on my EADI. Those events happened at almost the same time. Within a second; the screens came back on; and the flags went away. There was a Master Caution light illuminated now; and it was for an electric look-up light. On the overhead panel; the 'Bus Tie' connect and 'Left Generator' warning lights were illuminated. I called for the electrical; non-normal checklist. The Captain worked through the checklist; and after the checklist was finished which lead us to declare an emergency; she then contacted Dispatch and company while I flew the aircraft. We continued the arrival as filed. Later; closer to ZZZ passing 5;400 FT; ATC asked us 'Were you assigned 6;000 FT?' to which we replied; 'No; we were assigned 4;000 FT.' The rest of the flight continued without incident.