RDZ-35 two-post disconnector, rated voltage 35 kV
RDZ-type disconnectors are intended for making and breaking de-energized sections of an electrical circuit energized up to 35 kV, as well as for earthing (grounding) the isolated sections by means of earthing switches integrated with the disconnectors. The disconnectors are available in single-pole, two-pole and three-pole versions. The pole connected to the operating mechanism is the driving (leading) pole. Operability is provided by operating mechanisms. Rotation of the operating shafts of the main circuit and of the earthing switch is performed manually using PR-2B or PRG mechanisms or by a motor operator PD-14.
The disconnectors are manufactured for environmental operation in accordance with EN/IEC 60721-3-4 (outdoor; replacement for former GOST 15150 U1), with the following typical limits:
– altitude not exceeding 1000 m;
– upper ambient air temperature +40 °C;
– lower ambient air temperature -60 °C;
– wind speed up to 40 m/s with no icing and up to 15 m/s with icing up to 10 mm;
– average annual relative humidity 80% at +15 °C;
– maximum wind pressure 700 Pa (equivalent to 34 m/s) with no icing;
– maximum wind pressure 140 Pa (equivalent to 15 m/s) with an ice crust up to 10 mm on surfaces;
– maximum total mechanical load on the terminals of one pole (from connected conductors considering wind and ice loads) - 500 N, provided it is evenly distributed across the terminals.
Dielectric strength complies with the requirements for 35 kV medium-voltage disconnectors per the IEC 62271 series (e.g. IEC/EN 62271-1, IEC/EN 62271-102). Creepage distance of external insulation for standard porcelain versions:
– for pollution degree I - not less than 70 cm;
– for pollution degree II - not less than 105 cm.
On request, RDZ units can be supplied on polymer post insulators type OSK8–35–B–2 for outdoor service per EN/IEC 60721-3-4, with creepage distance not less than 105 cm. Mechanical endurance of the disconnectors is 2000 open-close operating cycles.
The disconnectors are not intended for service under strong shock, vibration or impact.
Technical data
| Rated voltage, kV | 35 |
| Maximum system voltage, kV | 40.5 |
| Rated current, A | 1000; 2000; 3150 |
| Rated short-time withstand (peak making) current, kA | 63; 80; 125 |
| Thermal short-time withstand current (r.m.s.), kA | 25; 31.5; 50 |
| Duration of thermal withstand current, s – for main blades – for earthing switches |
3 1 |
Purpose and application
RDZ-35 is a two-post outdoor disconnector for 35 kV distribution systems. Its primary functions are: safe isolation of live parts without load current, creation of a visible isolating distance, preparation of equipment for maintenance and testing, and operational earthing of isolated sections using the built-in earthing switches.
Applications include 35 kV substation yards of utilities, busbar and line sectioning points, transformer connections, incoming and outgoing 35 kV OHL/cable feeders, interfaces with outdoor equipment and KRUN units, as well as distribution points of industrial and mining & metallurgical facilities. The disconnector can be used as a bus, line, transformer, bypass or sectionalizing device in single or double busbar schemes, with transfer buses, with automatic reclosing on lines, and in schemes considering protection, automation and metering. The visible break allows work to be performed under a permit-to-work in compliance with electrical safety rules.
RDZ-35 is well suited for renewable generation sites (wind and solar plants) at 35 kV grid connection points and for packaged modular substations. The apparatus is designed for frequent operational switching, outdoor weather exposure, and increased requirements for visible break length and dielectric strength of external insulation.
Service conditions
The standard outdoor execution corresponds to EN/IEC 60721-3-4 and ensures operability across a wide range of temperatures and environmental factors listed above. Materials and coatings are selected considering atmospheric corrosion, UV exposure and freeze-thaw cycling. All steel parts of the frame and linkages are made of structural steels with zinc coating (electroplated or hot-dip); additional paint systems can be supplied on request. Current-carrying parts are made of copper or aluminium alloys with appropriate anti-oxidation protection.
The disconnector may be installed in polluted atmospheres by selecting an appropriate creepage distance (for pollution degree II - not less than 105 cm). For icing-prone regions, mechanisms have torque margins and reinforced return springs. Wind loads and mechanical forces transferred from conductors to terminals are considered when selecting installation height and support structures.
Design and configuration
RDZ-35 consists of a base frame, two insulator posts (two-post design), a current path with moving and fixed contacts, an operating shaft with linkages and position-locking mechanism, and an optional earthing switch. The two-post arrangement provides high mechanical stability and rigidity of the contact path at high currents and wind loads. The blade has a tubular or box-type design to reduce heating and improve current distribution.
The moving blade rotates about its axis by 90° or 180° (depending on execution), forming a clear visible isolating distance. Fixed contacts are equipped with spring pressure devices to ensure stable contact force under thermal expansion and vibration. Contact surfaces are typically galvanically coated (tin/silver) to reduce contact resistance and improve corrosion resistance. Current-carrying parts are rated for 1000, 2000 and 3150 A with corresponding thermal and dynamic short-circuit withstand.
Support insulators - porcelain or polymer (on request). Polymer OSK8–35–B–2 insulators provide higher pollution performance, lower weight and vibration resistance; porcelain insulators offer high mechanical strength and durability. Terminals are suited for bolted connections with flat or pin contacts and accept standard cable lugs, flexible bars and ACSR/AAAC conductors of appropriate cross-sections. Typical and customized layouts are available to match phase spacing and bus heights.
Operating mechanisms: manual PR-2B/PRG units provide operational switching with end-position latching, padlocking capability, visual “ON/OFF” indicators, and auxiliary contacts for remote indication. Motor operator PD-14 enables remote control and integration into SCADA; cabinet and auxiliary-circuit heaters can be supplied on request. Linkages and joints are designed to compensate thermal expansion and allow fine adjustment of pole synchronism.
| Feature | Available options | Notes |
| Number of poles | 1 / 2 / 3 poles | Driving pole - with mechanism connection |
| Earthing switch | None / single-side / double-side | Integrated with the disconnector |
| Insulation | Porcelain / polymer | Polymer - enhanced pollution performance |
| Blade rotation angle | 90° / 180° | Selected per yard layout and bus position |
| Operating mechanism | PR-2B, PRG, PD-14 | Manual or motor; remote indication |
| Terminal layout | In-line / angle | For “bus-to-bus” or “line-to-bus” connections |
| Add-ons | Aux. contacts, limit switches, indicators | For SCADA, telesignaling, interlocks |
Safety and interlocking
The design provides mechanical and electrical interlocking of earthing switch operation: the earthing switch can be closed only when the main blades are fully open. Position latches for “ON/OFF” and “EARTHED”, padlocking of mechanism levers, and key interlocks are available to prevent mal-operations. Limit switches and auxiliary contacts are used for remote position monitoring.
A visible isolating distance, adequate clearances and creepage distances, and increased creepage length of the insulation ensure the required electrical safety for permitted work. All live parts have smooth profiles and protective covers at possible touch points, in line with industrial safety requirements.
Versions and options
In addition to the base versions, options include modified terminal heights, 90°/180° blade rotation, various inter-phase spacings (to match the busbar scheme), reinforced support insulators, auxiliary contacts for remote indication, and the PD-14 motor operator for SCADA integration. On request, supply with cable terminations, inter-panel linkages and mounting brackets tailored to the specific 35 kV yard steelwork is available.
Compliance with standards
- IEC/EN 62271-102 - AC disconnectors and earthing switches.
- IEC/EN 62271-1 - Common requirements for medium-voltage switchgear and controlgear.
- EN/IEC 60721-3-4 (outdoor) and EN/IEC 60721-3-3 (indoor) - Environmental conditions (replacement for former GOST 15150 U1/U3).
- IEC 60060-1 - High-voltage test techniques - Part 1: General definitions and test requirements.
- IEC 60273 / IEC 60168 - Characteristics and tests of indoor/outdoor post insulators for systems >1 kV.
Engagement with contractors, manufacturers, investors
We are open to cooperation with mechanical engineering plants, investors and installation companies to organize series production and/or localization of the RDZ-35. We provide complete design documentation, routings, bills of materials, lists of purchased components, material and coating requirements, and factory acceptance test procedures. Supply of subassemblies (contact system, earthing switches, linkages, operator units) and training of partner personnel are available.
For installation contractors we offer supervision, author’s oversight, commissioning, and training of operations and maintenance staff. For investors and production organizers - cost calculation, recommendations on shop equipment (presses, welding and plating equipment, test benches), and support of the pilot batch.
Available documentation (drawings, 3D models, CAD)
Available formats: DWG/DXF (AutoCAD), SLDDRW/SLDPRT/SLDASM (SolidWorks), STEP/Parasolid, PDF. On request we prepare 3D models for BIM projects, data sheets, connection diagrams, as well as installation, adjustment and operating instructions. The documentation set is adapted to your project requirements and manufacturing capabilities.
Advantages of working with us:
– No need to maintain a large team of highly qualified engineers - you receive a complete documentation package for manufacturing, suitable for an engineer of average qualification.
– No need to build pilot prototypes - our experience allows launching serial production directly.
– Working to our documentation, your specialists receive consulting on all nuances of RDZ-35 disconnector manufacturing.
For additional information on RDZ-35 disconnectors, please contact: inbox@proekt-energo.com
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