Busbar system with ERIP-insulation for medium voltage

The ISOBUS MR system provides a value added solution for primary and
secondary distribution up to 52kV and 7000A for indoor and outdoor applications.

ERIP Insulation Properties

PBP Preissinger uses Epoxy Resin Impregnated Paper as the main component in our composite insulation medium. Design, manufacture and installation processes ensure an installed product with a very long lifespan, which is basically »fit and forget.«

Medium Voltage Application

Generator lead out Transformer – switchgear connections Switchgear – switchgear connections Switchgear - cable connection

>3,6 kV- 52 kV, -7000A

Degree of protection
IP30-IP54 indoor,
IP54-IP67 outdoor
Capacitive grading device


Basic Design

  Design starts with data capture from our clients because we dimension ISOBUS MR systems according to specific project requirements. This data comprises voltage, current, short circuit current, frequency and ambient temperature. At the design stage, we engineer the ISOBUS MR solution to provide the shortest and safest routes between electrical equipment. E.g. we have right angled plug-in connectors between switchgear and cable, therefore eliminating the need for cable basements.


Safety and Reliability

  • Touch safe under operational conditions.
  • Partial discharge free acc. to IEC 60 137 due to void free manufacture & high voltage routine testing of each section
  • No phase to phase short circuit due to complete encapsulation and insulation of each phase
  • No flashover due to embedded capacitive field control through the insulation
  • Insulation withstand is E-120
  • Easily withstands ambient temperatures from below -50°C to +55°C
  • Degree of protection up to IP68. Suitable for harsh environmental conditions
  • Natural cooling
  • No halogens. If a fire occurs no toxic gases develop and the insulation is self-extinguishing
  • Very high dynamic and thermal short circuit capability.

Busbar - Busbar Connection

  ISOBUS MR is a modular system and the maximum busbar length is determined by the autoclave dimensions. Therefore connections between busbars are made as shown.


Electro-Technical Equipment-ISOBUS MR Connection


  It is very easy to connect the ISOBUS MR system with all makes and types of electro-technical equipment available in today’s market. Whether generator lead out, transformer connections, switchgear connections or cable connections. The following list shows the connection options at a glance:
  • Connections to flat terminals according to DIN 46206 or customer specifications (Fig. 3)
  • Connections to round bolts
  • Connections to SF6 switchgear
  • Touch safe connections into transformers and air insulated switchgear using junction box
  • Plug-in connections (Fig. 4)

Fixing System

  For each project, PBP Preissinger design and supplies an easy to assemble, modular fixing system, that allows for compensation of tolerances during installation. We use special computer programmes in house, to calculate the technical requirements. E.g. short circuit, temperature rise, natural frequency, and from this information the fixing system is produced, together with the installation documentation.


Physical Components

The conductor can be E-Cu or E-AlMgSi and is either tubular or cylindrical The insulation consists of :

  • Crepe paper wound round the conductor
  • Embedded capacitive grading which ensures even voltage distribution at the busbar ends
  • A concentric earth layer on the outside plus a copper stocking ensures touch safety during operational conditions.
This construction is then impregnated with epoxy resin under vacuum and heat conditions. The dimensions of our autoclave are 8 meters X 2 meters X 2 meters. The outer sheath is always metal for outdoor applications, with degree of protection IP 54-IP 68, (Fig. 6). On outdoor applications, the grading devices are equipped with sheds which lengthen the creepage distance. The outer sheath is heat shrink for indoor applications, with degree of protection IP 30-IP 54.

Routine Testing

Following manufacture, we conduct routine high voltage testing in our own laboratory. Every manufactured component is subject to the following tests prior to delivery:

  • Power frequency test
  • Partial discharge test
  • Capacitance measurement
  • Tan delta measurement
  • Quality assurance according to ISO 9001