The purpose of this thesis was to determine the condition of 690 VAC motor control centers relay protection in Metsä Fibre Rauma pulp mill. In addition to that survey was made about new equipment to replace the old ground fault monitoring equipment.

In this thesis Metsä Fibre Rauma pulp mill and Oy Botnia Mill Service Ab is presented generally. In addition protection relays functions and present condition are describe in this thesis. Thesis also includes suggestions to improve reliability and safety by protection relays.