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The Innovative and Efcient
High Voltage Padmount Transformer
AbStRACt A Request for Proposal (RFP) was sent to transformer
When Manitoba Hydro installed their first High Voltage manufacturers throughout North America, including
Padmount Transformer (HVPT) substation, the utility multinationals and niche regional market manufacturers.
with over 700,000 customers realized they truly had an The RFP called for 2.5 MVA and 5 MVA designs that would
innovative alternative to the expensive, unsightly and incorporate power transformer class windings and tank
dangerous conventional substations. The HVPT substation design. In addition, the designs would have to meet the
with its patented fully enclosed design is now the preferred electrical and mechanical requirements of American National
substation method in the province of Manitoba and has Standards Institute (ANSI) C57 or Canadian Standards
saved the utility millions of dollars in capital and operational Association (CSA) Standard C88. These designs were to
costs. The unique benefits of the HVPT substation are have an underground HV supply and an underground LV
very much applicable to the Caribbean and this paper will exit that was totally enclosed, secure, and tamperproof to
highlight the history and the benefits of this new innovative ANSI Standard C57. The difference was that the transformer
substation alternative. had to have no external devices that might require a fence,
a conservator tank, or on-load tap changer.
IntRodUCtIon
Manitoba Hydro is a Canadian energy utility with a distribution One Canadian manufacturer, Partner Technologies Inc.
system that serves approximately 800,000 customers over (PTI), was willing to consider this innovative idea and create
200,000 square miles. In the late 1990s, Manitoba Hydro the concept. Initial results indicated that a small 5 MVA
conducted a review of all distribution and sub-transmission pad-mounted substation with up to three feeders could be
planning and design practices. The review was conducted installed for approximately half of the cost of a conventional
to identify areas where capital costs could be reduced while substation. This new HVPT concept was proving initial
maintaining reliability. assumptions that it would be a cost effective method of
serving remote loads. Within eight months, the first two
HVPTs were installed, and continue to be used by Manitoba
This review determined that much of the corporation’s annual
capital outlay in distribution, in millions of dollars, was tied Hydro.
up in building and rebuilding distribution substations. A task
force was created with a mandate to investigate possible
cost reductions by redefining the criteria and practices that
guided the design, planning, and installation of substations.
During this review, it was mentioned that putting down a
pad-mounted distribution transformer in underground
distribution would be an effective and cost efficient option.
As a result, Manitoba Hydro implemented this concept.
thE pRopoSAL
While pad-mounted distribution transformers are not a new
concept, no one had attempted voltages of 69 kV and
above. Since all the components exist for the distribution
aspect, what remained was to create a high voltage pad- 10 mVA, 66 kV high Voltage padmount transformer
mounted transformer (HVPT).
industry Journal 18
