Shielded solid insulated switchgear at 35 kV (SSIS)

Since the end of 2015 JSC “NPO VEI Elektroizolyatsiya” together with FGBOU VO NIU “MEI” has been implementing a project for the creation of shielded solid insulated switchgears  (SSIS) for a maximum operating voltage of 35 kV within the framework of R & D: “Development of high-tech switchgears of voltage class 35 kV of various modifications with innovative types of insulating structures”.

This research and development work is carried out as a part of Government Decree No. 218-P of 09.04.2010 “On measures of state support for the development of cooperation between Russian educational organizations of higher education, state scientific institutions and organizations implementing complex projects for the creation of high-tech production , within the framework of the subprogram “Institutional development of the research sector” of the state program of the Russian Federation “Development of science and technology “on the 2013- 2020 years”.

Objective of the project:

Development of SSIS for a maximum operating voltage of 35 kV under normal and emergency conditions in three-phase alternating current grids with a frequency of 50 Hz for a rated voltage of 35 kV.

SSIS functions:

  • carrying out load shutdowns and switching;
  • disconnecting the outgoing line and its grounding for carrying out repair and maintenance operations on this line with the possibility of switching not only the load currents but also the short-circuit currents;
  • monitoring and measurement of currents and voltages.

SSIS operation:

The control and monitoring system provides the ability to transmit control signals and data from the monitoring sensors over the network using industrial data transfer protocols remotely.


Technical specifications:

The indicators The values ​​of the parameters (characteristics)
Basic Cell Parameters


Rated voltage, kV 35
The greatest working voltage, kV 40,5
Rated frequency, Hz 50
One-minute power frequency withstand voltage Between phases and ground relatively, kV 95
Between open contacts, kV 118
Lightning impulse withstand voltage, maximum value Between phases and ground relatively, kV 185
Between contacts, kV 215
Rated operational current of busbars, A 1250
Rated current of outgoing feeders, A 630


Development originality:

The presence of a grounded conductive layer on the surface of all internal elements of the SSIS under one potential in order to ensure increased safety and compactness.