What Is a Substation Gantry: Purpose and Voltage Classes

What an open-air switchyard is and why a gantry is needed

An open-air switchyard is the part of a substation that stands outdoors. It holds the equipment that receives and distributes electricity: busbars, disconnectors, circuit breakers, current and voltage transformers.

A gantry is a steel frame of two or more columns and horizontal beams. It holds the busbars, the insulator strings and the ends of incoming overhead lines at the height they need to be.

What else is on an open-air switchyard

A switchyard has more than gantries. Busbar supports carry the busbars between the gantries, the equipment (circuit breakers, disconnectors, current and voltage transformers) stands on its own support structures, and there are also surge arresters and a grounding loop.

Even so, the gantry takes the heaviest load: the weight of the busbars, the pull of the incoming overhead lines and the wind acting on the whole span.

Multi-sided or standard gantries

• multi-sided gantries: columns made of bent steel sections, each one designed for a specific substation project;
• standard gantries: built to unified albums of older design solutions. We check them against current codes and recalculate or modify them if needed.

Marks and sizes of standard gantries are tabulated in full on the page Typical Substation Gantries 35–500 kV.

Gantry shapes: single-column, portal-frame, angle

A single-column gantry has one column and takes a light load, for example a single device or the end of a line. A portal-frame gantry has two columns and a horizontal beam; it is the most common type for a busbar or line span. Angle (anchor) gantries are reinforced and are used where the route turns or the wires are tensioned.

Each type is calculated for its own loads: the number and cross-section of the wires, the turning angle and the voltage class.

Voltage classes of gantries

We make gantries for substations from 35 to 750 kV. The higher the voltage, the greater the clearance required between live parts and the ground, so the gantry has to be taller and heavier.

PUE requirements for gantries

The Rules for the Arrangement of Electrical Installations (PUE, 2026 edition) set the minimum clear distances from bare live parts to the ground, to earthed structures and between phases, and these depend on the voltage class (Table 4.2.1). Supporting structures for equipment, apparatus, live parts and insulators must be designed for weight, tension, switching operations, wind, ice, short circuits and seismic actions; steel structures must also carry an anti-corrosion coating (cl. 4.2.14). Wind and ice loads on the busbars and structures are to be determined from the climatic zoning maps and from chapter 2.5 on overhead lines (cl. 4.2.46); supports that hold busbars are to be designed as intermediate or end supports (cl. 4.2.48). At substations and switchyards of 330 kV and above, the Rules call for metalwork protected against corrosion by methods that need no regular renewal of the coating (galvanising or aluminising, for example), or for structures made of aluminium elements, so that staff spend less time in the zone of the electric field (cl. 4.2.192).

That is why every gantry is calculated for its own project. The exact clearances and loads depend on the voltage class and on the wind and ice region of the site; the designer takes the final values for a specific installation from the current text of the PUE.

Corrosion protection and installation

Multi-sided gantries are made from a closed bent profile and hot-dip galvanised on both sides, outside and inside, to DSTU EN ISO 1461:2024. This is what gives them a much longer service life than standard lattice gantries: those often have lap-welded joints without a closed seam, which the galvanising rules do not allow.

The column is fixed to the foundation by a flange, through a tubular anchor cage that also has a flange. The advantages of multi-sided gantries over standard ones are covered in Multi-Sided Substation Gantries: Design and Foundations.

What to provide for a gantry calculation

Skip anything you do not know, and we will clarify it ourselves. The calculation needs:

• a switchyard layout drawing: the number of columns, the span and the height to the beam;
• the voltage class and the single-line diagram of the switchyard;
• loads: the number and type of wires, the wire tension, and the turning angle for an angle gantry;
• the wind and ice region and the soil under the foundation;
• for a standard gantry, its mark and design number from the documentation.

Common mistakes

• choosing a gantry by voltage class alone, with no wire loads taken into account;
• an angle or anchor gantry not marked as such, although that type has to be reinforced;
• the foundation and soil left unchecked;
• the column height given, but not the height to the beam, which the clearances to the ground depend on.

Gantry types by purpose: busbar, bay, jumper, line

Besides the shape (single-column, portal-frame, angle), the standard albums tell gantries apart by purpose. It shows in the mark: the letter after the voltage class. Ш (Sh) means a busbar gantry, Я (Ya) a bay gantry, П (P) a jumper gantry, Т (T) a transformer gantry and Л (L) a line gantry. The letter С (S) at the end of a mark (ПС-35ШС) denotes the version for northern regions. In marks such as ПСЛ-110Я1 and ПСТ-110Я1 the letters Л and Т stand before the voltage class and do not give the type: in the catalogue these are bay gantries (Я).

Based on the page Typical Substation Gantries 35–500 kV: 111 marks in all, including the versions for northern regions. The exact connection scheme comes from the layout drawing of the switchyard.

Which gantry types exist at each voltage class

The higher the voltage class, the bigger the gantry. The heaviest gantry in the catalogue (ПС-500-Л3, 14,724 kg) is more than 20 times as heavy as the lightest (ПС-35ШС, 647 kg); the table of masses and posts by voltage class is on the page Substation Gantries. The table below shows how many marks of each type exist at each class.

Line gantries appear only at 500 kV, jumper gantries at 330 and 500 kV and transformer gantries at 330 kV; at 35–220 kV the catalogue has only busbar and bay gantries. The count includes the versions for northern regions.

Multi-sided and standard gantries: what differs

A standard gantry is taken from an album, a multi-sided one is calculated for a particular substation. The table gives what is not covered above: the post, the calculation and the sizes.

Dimensions and equipment of the 110 and 150 kV types are in the catalogues 110 kV Substation Gantries and 150 kV Substation Gantries.