Dr. Khella graduated from Cairo University (Egypt) in 1955 with a B.Sc. degree in Electrical Engineering and obtained his Ph.D. from Dresden University (Germany) in 1962.

After graduation, he worked for the Suez Oil Refinery in Egypt for 13 years (of which 4 years post-grad in Germany) as a project Engineer responsible for the installation, start-up and maintenance of distribution substations, cable networks, switchgear and motor drives.

In 1968, he immigrated to Canada and joined Hydro Mississauga and then Etobicoke Hydro. During the 25 years employment with these 2 Municipal Hydro Utilities, he took the positions of Design Engineer, Distribution Engineer and Manager of Planning and Design Department responsible for preparing/reviewing/approving many projects pertaining to system studies, system expansion, system conversion, material specifications, construction standards, work methods, protection and control and computer applications.

In 1994, he retired from Etobicoke Hydro as a Manager of Distribution Planning and Design Department and established his company, W. H. KHELLA ENTERPRISES, a PEO certified consulting business specialized in providing engineering services to the electrical utilities and industry. He conducts system studies, design, protection/coordination work and lectures power engineering courses for Hydro Utilities and Continuing Educational Programs in Canada and abroad.

During his employment with Hydro Utilities, Dr. Khella served on various committees for the:
- Association of Municipal Electric Utilities (MEA)
- Canadian Standards Association (CSA)
- Metropolitan Toronto Public Utilities Coordinating Committee (MTPUCC)
- Canadian National Committee(CNC) of the IEC
- Currently, he is a member of 2 CSA Committees.

Dr. Khella is a Registered Professional Engineer with PEO, a Fellow of the Engineering Institute of Canada, and a Senior Member of IEEE. He held the following positions in the IEEE Toronto Section; Coordinator of Educational Activities, Secretary, Treasurer, and Chairman. He is currently a member at large of the IEEE Toronto Section, and a member of the Board of Directors of the IEEE Canadian Foundation. He is a recipient of the IEEE Millennium Medal for valued services and outstanding contributions.

During his career in Egypt and Canada, Dr. Khella developed and lectured specialized courses in electrical power engineering such as:
- Electrical Equipment for hazardous locations (Suez Petroleum Institute)
- Power Engineering credit courses (Ryerson and Centennial)
- Professional development seminars covering all aspects of Distribution System Equipment Application and Protection/ Coordination (IEEE, U of T, EPIC & several Hydro Utilities)
- Power Line Design (Jamaica Power Service, Kingston)
- Distribution System Engineering and Analysis (ZESA, Zimbabwe, Harare)
- Distribution System Design, Construction and Maintenance Standards (LUCELEC, St. Lucia)