DURING A NIGHT OP AND AFTER NUMEROUS GENERATOR TIPS OF #1 GENERATOR AND ASSOCIATED ELECTRICAL DISTRIBUTION PROBS; A B757-200 FLT CREW DECIDES TO DIVERT TO ZZZ.

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PASSING FL190; CAPT (PF) ENGAGED 'C' AUTOPLT. WE NOTICED INTERMITTENT JERKINESS IN THE AUTOPLT. CAPT DISCONNECTED 'C' AUTOPLT AND ENGAGED 'L' AUTOPLT. SAME RESULTS; BUT THEN WE NOTICED THAT CONCURRENT WITH THE JERKS IN THE AUTOPLT WAS A CYCLING FROM BRIGHT TO DIM OF THE ACARS SCREEN. ENGAGED 'R' AUTOPLT AND JERKS STOPPED; BUT ACARS STILL INTERMITTENTLY WENT DIM. HAD DISPATCH CONTACT US WITH MAINT CTL AND WROTE UP THE PROBS AND TOLD THEM OF OUR SUSPICION OF A BUS/ELECTRICAL PROB. ABOUT 100 MI SSE OF SLC; L GENERATOR TRIPPED WITH AN L ISOLATION LIGHT. CONSULTED FLT MANUAL AND RESET L GENERATOR. L ISOLATION REMAINED ILLUMINATED. STARTED APU FOR BACKUP FOR R A/C PWR. RE-ENGAGED 'R' AUTOPLT AND CONTINUED AT FL390. AT 160 MI NNE OF ZZZ; L GENERATOR TRIPPED AGAIN WITH AUTOPLT DISCONNECT AND NUMEROUS EICAS MESSAGES. CAPT WAS TALKING WITH MAINT CTL BUT LOST COMS. HAD ATC RELAY INTENTION TO DIVERT TO ZZZ. DECLARED EMER AND PROCEEDED TO ZZZ. SEVERAL UNEXPECTED ELECTRICAL PROBS ENSUED ENRTE TO ZZZ. THE EICAS HAD COMPACTED; BUT INTERMITTENTLY WENT TOTALLY BLANK. BOTH ALT INDICATORS TURNED BLACK AND WHITE INTERMITTENTLY. CABIN AND COCKPIT GOT WARM. SELECTED PACKS TO 'C.' INFORMED FLT ATTENDANTS AND PAX OF DEV. ON APCH TO ZZZ; FLAPS WERE SLOWER TO MOVE THAN EXPECTED. VISUAL RWY 25R UNEVENTFUL LNDG.