Narrative:

The maintenance history indicated that on the previous day; after the loss of the 'left gen bus' several electrical problems arose that appeared to be related; loss of galley power; aft cabin electrical outlets inoperative; egpws terrain awareness; aft equipment cooling fan; and the overboard exhaust valve open (status messages). The maintenance action indicated 'test ok ops normal' with no corrective action taken; so we expected the problem to return and reviewed the associated QRH procedures just in case.on climb-out; passing 25;000 feet; the left generator disconnected. We ran the QRH procedure for gen off and restored the generator. The QRH says that if the gen cont off light extinguishes; you can continue normal operations; so both dispatch and [maintenance control] encouraged us to continue to ZZZ. [However]; the gen off QRH makes no mention of the bus tie isolation light; which remained illuminated. The bus isolated QRH directed us not to reset the bus tie breaker in flight; and noted that the only available source of power for the associated AC bus is the associated engine driven generator. The APU or the other engine driven generator would be unavailable and a subsequent generator failure would have forced us to land at the nearest suitable airport; potentially in the dark; with multiple electrical failures. Since the maintenance history showed that the same generator had failed in-flight during the previous day; we felt there was a high probability of a subsequent failure. After consulting dispatch and [maintenance control] via arinc phone patch; we [advised ATC] and diverted to ZZZ1 where we landed uneventfully 2;000 pounds overweight.communication with dispatch and [maintenance control] was difficult due to the fact that the 757-300 is not equipped with satellite cpdlc. We were approaching the boundary between centers where we lose VHF communications and were forced to rely on scratchy HF communications. We could not evaluate weather at the various possible alternates without great difficulty. Clearance from [center] was delayed by ATC's untimely request for the number of souls on board and fuel remaining. There was plenty of time (1:10) to provide this information after we received our clearance. In retrospect; we should have diverted immediately instead of waiting for a clearance. Every minute of delay increased the chances of a subsequent generator failure and forced diversion to the nearest suitable airport instead of the best available alternate. Distractions (threats) were increased due to flight attendant calls from each galley instead of routing communications through the purser/lead.we were receiving a line check from a line check airman whose knowledge and input were very helpful in resolving the situation. She was able to access various references in the ipad and interface with the passengers while we spoke to arinc and the company using both HF radios simultaneously. She noted that ATC communication from the jump seat was difficult since she was sitting on the right side behind the first officer; but the observer's audio panel is on the left side behind the captain.runway xxl was closed for landing so we requested runway xxr for landing since it was the longest available runway and we would be landing overweight. ATC denied our request for runway xxr; stating that no heavies would be able to depart from runway xxr until after we landed; despite the fact that we were still nearly an hour from reaching [the nearest suitable airport]. We had difficulty receiving landing data; but when we finally received it; we saw that the winds favored runway yyr. We could easily land on it at our weight so we landed uneventfully and taxied to [the] gate.a representative from the station was eager to turn the airplane as fast as possible and inquired about our 'legalities' without regard for any human factors. This probably would not have happened at a pilot base since we are usually met by a flightoperations representative after a diversion to assess our mental state. I told the station representative that we were no longer fit for duty today and would be fit for duty the following day. I then relayed this information to the dispatcher and flight operations; who were both courteous and helpful. They secured hotels and transportation for the flight crew; but the cabin crew received no information about their layover or subsequent assignments.I called transportation to learn when our transportation would arrive and was told that vans were already waiting for the pilots as well as the flight attendants; so I returned to the jet to inform the flight attendants that their transportation was waiting to take them to a different hotel. We exchanged contact information; but the mobile application did not have current information regarding our flight attendants; perhaps due to the recycled flight number with a new departure date.we departed the following morning after the generator control unit (gcu) was replaced. We had several problems with ACARS; perhaps due to the fact that the flight number was recycled from the previous day and a radio call sign was used. The first officer was not shown as fit for duty and we could not uplink the winds aloft.

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Original NASA ASRS Text

Title: A B757-300 flight crew reported that during climb the Left Generator disconnected and the Left Bus-Tie Isolation light remained illuminated. They were able to reset the generator; but unable to reset the Bus-Tie per the QRH.

Narrative: The maintenance history indicated that on the previous day; after the loss of the 'L Gen Bus' several electrical problems arose that appeared to be related; loss of galley power; aft cabin electrical outlets inoperative; EGPWS terrain awareness; aft equipment cooling fan; and the overboard exhaust valve open (status messages). The maintenance action indicated 'Test OK ops normal' with no corrective action taken; so we expected the problem to return and reviewed the associated QRH procedures just in case.On climb-out; passing 25;000 feet; the left generator disconnected. We ran the QRH procedure for GEN OFF and restored the generator. The QRH says that if the GEN CONT OFF light extinguishes; you can continue normal operations; so both Dispatch and [Maintenance Control] encouraged us to continue to ZZZ. [However]; the GEN OFF QRH makes no mention of the Bus Tie Isolation Light; which remained illuminated. The BUS ISOLATED QRH directed us not to reset the bus tie breaker in flight; and noted that the only available source of power for the associated AC bus is the associated engine driven generator. The APU or the other engine driven generator would be unavailable and a subsequent generator failure would have forced us to land at the nearest suitable airport; potentially in the dark; with multiple electrical failures. Since the maintenance history showed that the same generator had failed in-flight during the previous day; we felt there was a high probability of a subsequent failure. After consulting Dispatch and [Maintenance Control] via ARINC phone patch; we [advised ATC] and diverted to ZZZ1 where we landed uneventfully 2;000 pounds overweight.Communication with Dispatch and [Maintenance Control] was difficult due to the fact that the 757-300 is not equipped with Satellite CPDLC. We were approaching the boundary between Centers where we lose VHF communications and were forced to rely on scratchy HF communications. We could not evaluate weather at the various possible alternates without great difficulty. Clearance from [Center] was delayed by ATC's untimely request for the number of souls on board and fuel remaining. There was plenty of time (1:10) to provide this information after we received our clearance. In retrospect; we should have diverted immediately instead of waiting for a clearance. Every minute of delay increased the chances of a subsequent generator failure and forced diversion to the nearest suitable airport instead of the best available alternate. Distractions (threats) were increased due to Flight Attendant calls from each galley instead of routing communications through the purser/lead.We were receiving a line check from a Line Check Airman whose knowledge and input were very helpful in resolving the situation. She was able to access various references in the iPad and interface with the passengers while we spoke to ARINC and the company using both HF radios simultaneously. She noted that ATC communication from the jump seat was difficult since she was sitting on the right side behind the First Officer; but the observer's audio panel is on the left side behind the Captain.Runway XXL was closed for landing so we requested Runway XXR for landing since it was the longest available runway and we would be landing overweight. ATC denied our request for Runway XXR; stating that no heavies would be able to depart from Runway XXR until after we landed; despite the fact that we were still nearly an hour from reaching [the nearest suitable airport]. We had difficulty receiving landing data; but when we finally received it; we saw that the winds favored Runway YYR. We could easily land on it at our weight so we landed uneventfully and taxied to [the] gate.A representative from the station was eager to turn the airplane as fast as possible and inquired about our 'legalities' without regard for any human factors. This probably would not have happened at a pilot base since we are usually met by a FlightOperations representative after a diversion to assess our mental state. I told the station representative that we were no longer fit for duty today and would be fit for duty the following day. I then relayed this information to the Dispatcher and Flight Operations; who were both courteous and helpful. They secured hotels and transportation for the flight crew; but the cabin crew received no information about their layover or subsequent assignments.I called Transportation to learn when our transportation would arrive and was told that vans were already waiting for the pilots as well as the Flight Attendants; so I returned to the jet to inform the Flight Attendants that their transportation was waiting to take them to a different hotel. We exchanged contact information; but the mobile application did not have current information regarding our Flight Attendants; perhaps due to the recycled flight number with a new departure date.We departed the following morning after the Generator Control Unit (GCU) was replaced. We had several problems with ACARS; perhaps due to the fact that the flight number was recycled from the previous day and a radio call sign was used. The First Officer was not shown as fit for duty and we could not uplink the winds aloft.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.