What was found
FLIGHT 7801 PHX - HII DISCREPANCY: ON DESCENT INTO HII, GENERATOR SHOWING 32 VOLTS THEN STANDBY ELECT POWER ON ANNUNCIATOR ILLUMINATED. GENERATOR OFF ANNUNCIATOR ILLUMINATED, STANDBY ELECT POWER INOP ANNUNCIATOR ILLUMINATED THEN BOTH STANDBY POWER CIRCUIT BREAKERS POPPED. AIRCRAFT WAS RETURNED TO PHX, EMERGENCY WAS DECLARED. LANDED WITHOUT FURTHER INCIDENT. CORRECTIVE ACTION: MAINTENANCE ADJUSTED THE GCU AND REPLACED AND ADJUSTED THE ACU. NO OTHER DEFECTS NOTED.