The custom transformer process runs in four stages, and most of the schedule risk sits in the first one. A quotation based on a partial specification is a guess, and a design released to manufacturing before the drawing is approved is an expensive way to find that out.
Step 1: Requirements Gathering and Initial Consultation
The enquiry arrives as a load, a site, and a problem. What we need out of the first exchange is the electrical ratings, the duty profile, the environmental conditions, and any physical constraint that cannot be changed.
What comes back is an assessment rather than a price: whether the requirement is something we build routinely, whether it sits at the edge of what we would take on, or whether it falls outside our range entirely. Saying that early is cheaper for both sides than discovering it at the drawing stage.
Two questions do most of the work here. What is the load actually going to be, not what is on the nameplate today. And what is the worst condition the unit has to survive, whether that is ambient, fault level, or an overload nobody has written down.
Step 2: Conceptual Design and Quotation
The engineering team takes the agreed requirements and produces a concept: core and winding arrangement, the cooling method, the insulation system, and an outline envelope.
That concept becomes the quotation. The quotation carries the technical specification, the price, the lead time, and the terms, and it should be read as a technical document rather than a price sheet. If a parameter in it is wrong, correcting it after the order has a cost; correcting it before does not.
Step 3: Detailed Engineering and Drawing Approval
Once the order is placed, the concept is developed into a full design: winding details and conductor sizing, the core build, insulation coordination, impedance, thermal calculations including any harmonic loss, and the mechanical design against fault forces.
Manufacturing drawings and the technical documentation set follow from that. The important part of this stage is the approval cycle. For anything non-standard, or where the transformer interfaces with existing switchgear or busbars, a design review with the customer is worth the time it takes. Dimensions, terminal positions, and cable entry directions are far cheaper to change on a drawing than on a finished unit.
Step 4: Manufacturing, Testing, and Delivery
Manufacturing then runs to the released design: core cutting and stacking, winding, drying and impregnation or casting where the design calls for it, assembly, and finishing.
Testing follows the programme agreed at quotation. Routine tests run on every unit; type tests demonstrate a design meets the standard; special tests are agreed for a project, and witness testing is arranged where the customer or their inspector wants to attend.
Test results are documented and issued before shipment, along with the drawings and manuals. Packing is specified against the transport route and the destination climate, particularly for sea freight on a cast resin unit, which is heavy and does not tolerate a badly designed lifting arrangement.
After delivery we can provide installation guidance and commissioning support. The unit should be inspected on arrival and kept dry and energised or heated until it goes into service, which matters in humid locations and matters more the longer the storage period.
Where Projects Slip
- The duty cycle was left blank, and the thermal design is based on an assumed profile.
- The available space was described by a room dimension rather than by the actual access route.
- The supply voltage was quoted as nominal without the tolerance, and the ratio needs a tap that was not specified.
- The standard and test programme were decided after the quotation, changing both price and schedule.
- The drawing approval cycle ran in parallel with manufacturing in an attempt to save time.
Time to Allow
Schedule is set by three things: how complete the specification is at enquiry, how many approval rounds the drawing needs, and what testing is required. A specification that arrives complete with the duty profile and the standard removes more time from the programme than any internal optimisation can.
See the custom transformer range, or contact us to start at Step 1.
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