Western Power has signed new a managed services contract with ASG group.
ASG said the contract is worth up to $40 million, based on a three-year base term and the option of two two-year extensions.
ASG has an existing five-year managed services contract with Western Power.
The new contract includes managing the utility's data centre consolidation program and a vendor transition program.
"In the utilities space, ASG is leading the way," ASG CEO Geoff Lewis said in a statement.
"Our reputation, pricing model and industry experience are proving to be the winning combination to secure these large deals.
"ASG understands the business imperatives for Utility providers and we have the experience in implementing effective solutions. We also have the know-how to ensure a smooth transition utilising our New World operating model."
Last month ASG announced it had won a $35 million, five-year managed services contract with contracting firm CIMIC Group.
Other wins revealed this year include State Super Financial Services in NSW, the federal Department of Communications, and electricity provider Synergy.
Earlier this year ASG posted revenue of $80.1 million for the first half of FY15. Net profit after tax (NPAT) for the half was $5.7 million.
The ASX-listed IT services company reports its full year results on 18 August.