Before ordering a dry-type transformer busway interface, bring the transformer and busway terminal geometry, conductor correspondence, mechanical support, enclosure boundary and supply responsibilities into one coordinated approval package. A busway rating or cable-terminal drawing alone does not establish a compatible interface. Approval must identify the exact equipment, drawing revisions and project requirements. Keep unresolved dimensions or responsibilities visible before either supplier releases the affected components for manufacture.
Dry-type transformer busway interface: approval record
This guide is for EPC teams, consultants and industrial procurement teams preparing a transformer-to-low-voltage-busway connection. It addresses purchase and drawing approval, without providing a site wiring procedure.
Combine the transformer general arrangement and terminal drawing with the busway route and termination drawing. Name the viewing direction, dimensional datum, equipment references and revision of each document. Record the applicable project specification and the party authorized to accept the interface. A drawing marked “for information” should not silently become the manufacturing release.
For the wider transformer selection inputs, review the dry-type transformer project requirements. The product page is a starting point for an enquiry, not proof that a particular busway fits.
Approve the mating geometry before fabrication
The cited July 2026 system design guide distinguishes a flange connection for a dry-type substation transformer from a throat connection for a liquid-filled transformer. Its dry-type example uses flexible connectors between the transformer low-voltage spades and flange bus bars, with a flange plate fixed to the enclosure. The accompanying drawing asks for transformer measurements. These are examples for that documented system, not interchangeable connection designs. Do not transfer their dimensional details to a different transformer or connection type.
Ask both suppliers to close the following items on coordinated drawings:
| Approval item | Information to record |
|---|---|
| Position and orientation | Connection face, elevation, datum and viewing direction |
| Mechanical mating | Flange outline, opening, hole pattern and fixing responsibility |
| Electrical termination | Terminal centres, thickness, contact arrangement and supplier-approved connection detail |
| Transition space | Required adapter or transition enclosure, access and interference checks |
| Movement and support | Connection movement limits, support layout and permitted equipment loads |
| Enclosure boundary | Cover, seals, bonding provisions and required protection at the interface |
A flexible connection does not justify leaving the terminal position unconfirmed. Obtain the proposed detail rather than asking the installer to resolve an unspecified gap.
Include the connection materials, approved hardware and tightening instructions in the interface package. Use the instructions for the actual terminal and busway connection; a torque value from a different product does not establish the correct value for the proposed joint.
Map conductors with an explicit viewing direction
Conductor labels need a defined orientation. In the cited January 2025 installation manual, phasing and orientation labels work with the supplied construction drawings; the documented busway is not symmetrical, and transposition sections change the orientation convention. Its stated conductor order is specific to that system.
For purchasing, request a terminal-to-terminal correspondence drawing covering each phase, the neutral where required, and the protective-earth arrangement. Distinguish physical terminal order from the project's electrical phase-sequence requirement. Record the required neutral duty and protective-conductor construction in the specification. Do not assume that a matching number of bars establishes matching functions, neutral capacity or an approved bonding arrangement.
Separate mechanical support from electrical connection
The cited connection-unit instructions require the mounting surface to be reinforced for the terminal element's weight and prohibit that weight from falling on its electrical connections. The instruction belongs to that connection-unit design. It provides a useful reason to request explicit load and support information for the proposed equipment.
The approval package should identify who designs and supplies busway hangers, structural attachments, enclosure reinforcement and terminal-element fixing. Ask for the loads allowed at the transformer interface and the loads imposed by the proposed connection. Assign the civil or structural review where required. Do not treat a flange bolt pattern as approval for the enclosure to carry the busway run.
Review flexible links and expansion sections separately
Flexible transformer links and busway expansion sections are separate components in the cited design guide. Its expansion section addresses relative movement of conductors and enclosure, with building expansion crossings and long runs considered in that system's design.
Ask the busway designer to identify the movement provisions required for the actual route. Ask the transformer supplier to confirm the connection limits for the proposed terminal arrangement. Record who supplies each component and the drawing that defines its duty. Neither “flexible link included” nor a generic spacing rule closes the route's expansion review.
Define protection and standards at the complete interface
An enclosure requirement must cover the assembled boundary. The cited connection-unit instructions require the cover connection to respect the equipment's protection specification and describe additional sealing for certain higher protection requirements. That does not establish a universal IP rating for transformer connections.
Identify the required protection at the transformer, transition enclosure and busway, then request the proposed seal and cover details. Keep ventilation and maintenance access requirements in the coordinated review rather than assuming that a sealed busway connection can alter the transformer enclosure without approval.
IEC 61439-6:2012 addresses low-voltage busbar trunking systems within its stated scope, including rated voltages up to 1,000 V AC or 1,500 V DC. A reference to that standard is not model-specific approval of a transformer interface. For North American projects, separately identify the specified busway requirements, transformer documentation and project acceptance route; do not substitute an IEC reference for the purchase specification.
Close the supply boundary and release record
Use a responsibility schedule for the flange, transition box, flexible connectors, connection hardware, seals, protective-conductor provisions and supports. Give each item a supplier, drawing reference, approval owner and status. Clarify whether installation materials and interface verification documents are included in the order.
Before release, resolve supplier comments on the same revisions. Retain the accepted interface drawings, listed deviations and final responsibility schedule. Changes to equipment position, terminal arrangement or busway routing should reopen the affected review. Use the project document requirements page to prepare the requested document list.
Procurement FAQs
Can we obtain a quotation before every interface dimension is final?
Yes, as a conditional quotation request. Identify the missing dimensions, assumptions and affected items. Ask the suppliers to state which information is needed before manufacturing release and whether later changes alter the quoted scope.
What should two separate purchase orders share?
They should reference the same accepted interface drawing and responsibility schedule. State which supplier provides each mating component and which party resolves a cross-supplier deviation. Otherwise, an item described as “by others” in both offers can remain unpurchased.
Does an approved cable-terminal drawing cover a later busway order?
No. A busway connection needs its own coordinated interface review. The cable-terminal drawing review explains the separate cable decision; do not carry its approval across to a different connection system.
How should a replacement project's existing dimensions be recorded?
Separate existing records from verified site information and proposed equipment drawings. Identify who confirms the installed geometry and any access constraints. A reused flange outline alone does not close the terminal, support or enclosure review.
What if a drawing revision changes after approval?
Identify the affected interface items and obtain renewed acceptance before releasing those items. Keep the superseded and replacement revisions in the project record. A revision number change should not be accepted without checking what physically changed.
Submit the interface requirements for discussion
Submit your project specification to HEAKOR with the transformer duty, destination, procurement stage and available transformer and busway drawings. Include document revisions, conductor requirements, support and enclosure requirements, and open supply-boundary questions. Mark missing information as TBC. This enquiry does not establish busway compatibility, interface manufacturing scope or project approval.
Technical references
- Low-voltage busway design guide, July 2026: sections 24.1-23 and 24.1-26, including figures 24.1-35/36; system-specific expansion and dry-type flange examples.
- Low-voltage busway installation manual, January 2025: construction drawings, phasing and orientation.
- Transformer/switchboard connection-unit instructions: mechanical securing and enclosure-boundary requirements for the documented system.
- IEC 61439-6:2012 official scope: low-voltage busbar trunking systems.