КТПМ-400/10/0.4 kV: a pole-mounted transformer substation for outdoor installation

The task

The site needed a transformer substation without a permanent structure: no substation building, no foundation works for a room, and the smallest possible footprint.

Three conditions shaped the design:

• Fully outdoor installation — the substation stands in the open all year, through rain, snow, wind and dust.
• Different protection needs in different compartments — the 0.4 kV equipment compartment has to be sealed tighter than the transformer compartment, which needs to breathe.
• Maintenance from outside — each compartment accessed by its own door, with no need to step "inside" the substation.

The solution

We built the pole-mounted substation as a single product on a support frame, divided into functional compartments with different protection ratings.

• Upper level, 10 kV. A frame with bushings, high-voltage fuses rated 31.5 A, and a compartment marked "РУ-10кВ" on the doors.
• 400 kVA power transformer — its own compartment with louvred vents for natural convection, doors marked "ТР-Р". This compartment is rated IP23: it needs airflow.
• 0.4 kV switchgear — the "РУ-0,4кВ" compartment rated 400 A: an offset-drive switch-disconnector, moulded-case circuit breakers with electronic trip units, surge arresters and terminal blocks. Rated IP54 — dust and water stay out.
• Remaining elements — IP34.
• Factory nameplate with type, rating, voltages and build date fixed to the enclosure: the parameters can be read on site without paperwork.

Three different IP ratings in one product is not an inconsistency but a calculation: the transformer needs air cooling, the 0.4 kV equipment needs to be sealed. Building the whole substation to the highest rating would cook the transformer.

The series product card: КТПМ pole-mounted substations. For designers: the typical solution "СТП 10/0.4 kV".

Figures (from the passport)

КТПМ-400/10/0.4 kV, serial No. 174116

LV switchgear contents: 400 A offset-drive switch-disconnector · 0.38/0.45 kV surge arresters — 3 pcs · 400 A moulded-case circuit breaker, 3P, 36 kA, with electronic trip unit.

Where it fits

A pole-mounted substation suits sites where building a substation room makes no sense: farms and livestock complexes, pumping stations and boreholes, yards and quarries, remote production areas, temporary construction supply.

Photo report: from frame to the finished substation

We'll size a pole-mounted substation for your site

Send us the rating you need and the connection arrangement — we'll select the design, the compartment protection ratings and the 0.4 kV switchgear contents. From questionnaire to factory testing and passport.