Panel of three people. Two of them will be from the department you are applying to, usually the head and a supervisor or associate. The third panelist will be from a different department.
Interview is competency-based. They may ask one technical question at most so read up and make sure you’re familiar with the substantive work of the department you apply for.
For competencies- refer to the job description. The required competencies are listed there and those are the competencies they will be testing you on. Prepare situational examples for each competency. They will ask about 3-4.