What was found
NR 1 OIL PRESSURE WENT TO ZERO AFTER TAKEOFF, LOST ATS & YAW DAMPER FAILED AT ROTATION. DID NOT LOSE ANY OIL QTY. ELECTED TO SHUTDOWN NR 1 AND RETURN TO DEPARTURE. NR 1 ENG WINDMILLED APPROX 30 MINUTES YAW DAMPER RESET BUT ATS SYS WOULD NOT. COMPLIED WITH QRH. THREE HYD SYS X'D OUT ON ECAM INDICATION. DOWN POWERED ACFT, NO CHANGE ON POWER UP. FOUND CIRCUIT BREAKER ON ACCESS BUSS BAR TRIPPED, RESET BREAKER AND LL FAULTS WENT AWAY. RAN NR 1 ENGINE AFTER NO OIL PRESSURE INSPECTION, COMPLIED WITH IAW JRH, ALL PARAMATERS NORMAL. TROUBLESHOOTING FOUND ESS TR WITH ARCED AND BURN THRU CASE AT CONNECTION. R & R ESS TR UNIT IAW MM 24-32-11-04. AS PRECAUTION, R & R AUTO TRANSFORMER IAW MM 24-51-11-04. OPS CHECKED NORMAL. SET ACFT UP INTO PREFLIGHT STAGE AND RAN ENGINES NR1 & NR2 PE JRH. ALL SYS OPS CHECKED NORMAL. ACFT OK FOR SERVICE.