Technical notes for electrical equipment buyers.

Network equipment selection · Medium-voltage switchgear

HJATIS modular ring main unit shown as an example of secondary medium-voltage distribution equipment

Ring main unit or metal-clad switchgear for an 11 kV network?

Start with the feeder duties, protection scheme and maintenance plan. The network voltage alone will not select the switchgear arrangement.

Transformer room planning · Transformers

HJATIS cast-resin dry-type transformer used to illustrate room ventilation planning

Dry-type transformer room ventilation: what to send with the layout

A useful room drawing shows where cooling air enters, where hot air leaves and which equipment produces heat. Start with the transformer loss data.

Switchboard maintenance planning · Low-voltage assemblies

HJATIS low-voltage switchboard lineup with withdrawable functional units

Fixed or withdrawable LV switchboards: choose around maintenance

Decide how the plant will isolate, repair and restore a feeder before choosing the functional-unit arrangement.

Transformer quotation comparison · Transformers

HJATIS oil-immersed distribution transformer used to illustrate quotation loss-data comparison

Comparing transformer quotations: no-load and load losses

Put the loss figures on the same test and operating basis before comparing two offers. Keep guaranteed values separate from estimates.

E-House transport planning · E-House procurement

HJATIS walk-in prefabricated electrical substation enclosure shown for E-House transport planning

E-House shipping splits: dimensions and access to settle before fabrication

Agree how the building will travel and be reassembled while the layout can still change. The delivery route belongs in the design discussion.

Transformer report review · Transformers

HJATIS cast-resin dry-type transformer used to illustrate a GB/T 1094.11 and IEC 60076-11 report review

GB/T 1094.11 and IEC 60076-11: checking a dry-type transformer report

Compare the tested transformer with the offered unit: ratings, enclosure, service conditions and the classifications specified for the project.

Switchgear report review · Medium-voltage switchgear

HJATIS 12 kV metal-clad switchgear used to illustrate a GB/T 3906 and IEC 62271-200 report review

GB/T 3906 and IEC 62271-200: the switchgear reports a buyer should compare

Check the tested panel, internal arc classification and service continuity category against the switchgear lineup offered for the project.

Assembly verification guide · Low-voltage assemblies

HJATIS withdrawable low-voltage switchgear used to illustrate IEC 61439 assembly verification

IEC 61439 design verification for an assembled LV switchboard

Ask for the design-verification basis of the offered switchboard and the routine-verification record for each completed assembly.

HJATIS Power · 27 August 2026 · 3 min read

E-House scope note · E-House procurement

HJATIS walk-in prefabricated modular substation used to illustrate an IEC 62271-202 scope review

Does IEC 62271-202 cover the complete E-House? A buyer’s scope check

List the equipment inside the E-House, the building services and the site connections. Assign the applicable standards and documents to each part of the supply.

HJATIS Power · 27 August 2026 · 3 min read

FAT field guide · E-House FAT

HJATIS modular substation at a remote project site illustrating pre-shipment E-House factory acceptance testing

What should an E-House FAT check before shipment?

Agree the test plan, check the installed equipment and test the protection, controls and auxiliaries together. Finish with signed results and a shipment punch list.

Site-input briefing · E-House site conditions

Prefabricated electrical cabin at an outdoor project site illustrating environmental design inputs for an E-House

Hot, humid, dusty or high-altitude site? E-House inputs to confirm before design

Give the design team measured site conditions and operating assumptions for insulation, cooling, filtration, corrosion protection and condensation control.