Date: 201902
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Electrical Distribution Busbar
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: Other takeoff roll
Result: Flight Crew Rejected Takeoff; Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: All ground operations were normal; the FO (First Officer) was the pilot flying. I took control of the throttles as they reached takeoff power. I made the 100-knot call out. Immediately after the 100-knot call; I looked at the upper and lower EICAS (Engine Indicating and Crew Alerting System) screens. The bottom screen was blanked and the upper screen had gone to the compacted mode. I made a quick scan of the engine instruments and saw the number 2 EPR (Engine Pressure Ratio) was blank. I elected to abort the takeoff. I announced 'Aborting' instead of 'Reject'; pulled throttles to idle; I expected RTO (Rejected Takeoff) to engage; and it did not. This threw me off and [I] pulled the reversers up; like a landing roll out; and then I manually deployed the speed brakes; which had not automatically deployed due to the RT AC bus failure. It all happened pretty quickly. As we were rolling out; I was perplexed why RTO had not engaged and looked; RTO was selected; but the 'AUTO BRAKES' light was illuminated. The FO announced the aborted takeoff to Tower. I then directed her to have the passengers remain seated. We cleared the RWY XL; and held short of [a taxiway] while we ran the RTO checklist. Since the lower EICAS was blank; we had no idea what the brake temps were. Using the RTO Checklist; we concluded we were in the caution zone. As I started to evaluate what exactly happened; the number 2 EPR was blank; and there was no oil pressure displayed on the number 2 engine. I determined the number 2 engine was indeed running; and directed the FO to shutdown the number 2 engine; since running engine without any indicated oil pressure didn't seem like a great idea. This was to me at this point obviously an electrical malfunction. The entire right side electrics were not working. R GEN CONT OFF light was illuminated; R BUS OFF light was illuminated; BUS TIE ISLN was illuminated. RT IRS (Inertia Reference System) on DC. All the emergency lights were illuminated; floor lighting was also illuminated; and none of the cabin lighting was operational.I asked the FO to contact Station Maintenance; while I talked to the flight attendants and passengers. Taxied to parking and advised Ramp of the possibility that our brakes were potentially in the Caution Zone.Uneventful taxi the gate. Maintenance came onboard and was able to determine that the wheel brakes were all at 1 or less. So no hot brakes. Plane swap.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B757 flight crew reported rejecting the takeoff at approximately 100 kts after the loss of the right AC bus resulted in several systems failures.