A pressure compensator is disclosed for a subsea electric installation, which includes a rigid bottle and a flexible bag placed in the rigid bottle, the pressure compensator including a first opening at a first end of the pressure compensator allowing fluid communication of an insulating medium arranged to intermediate space between the rigid bottle and the flexible bag, a second opening at a second end of the pressure compensator allowing fluid communication of seawater arranged within the flexible bag; and a bypass channel providing fluid communication between two points in the intermediate space of the pressure compensator.