GLO stands for Generator Lubrication Oil. This is a system designed to lubricate the generator bearings of the turbine.
D major components of the lubrication system are as follows; Lube oil reservoir, Generator-driven lube oil pump, Motor-driven auxilliary DC lube oil pump, Heat exchanger.
Whenever the generator rotor shaft rotates, the generator bearings must be lubricated to prevent damage, and so lube oil must be supplied to bearing assembly during start up, shut downs, at operational speed.
During startup a 125vdc auxiliary pump supplies lube oil until the mechanical pump reaches operational pressure and speed.