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SZR Transfer switch systems


  • Maintaining power supply in the facilities and networks that require continuous power supply due to critical location and functions;
  • Switching power supply sources according to the pre-set configuration, in a very fast way (restitution automatics);
  • Meeting the requirements of power supply reliability;
  • Distribution of electricity and protection of circuits on the LV side;
  • Protection of electrical devices against consequences of shortings and overloads.



Thermosetting plastic

SMC enclosure with IP 44 or 54 rating. Built to Class II protection standard, with HB to V0 flammability rating, painted in RAL 7035, with the possibility of additional painting to ensure temporary resistance to environmental factors and UV radiation.

Aluminium OU-1(2)

The enclosure made of aluminium sheet (welded or riveted). Powder painted in any colour. The size matching the type and range of devices and individual needs of the Client. The enclosure is highly resistant to degradation, environmental factors and UV radiation. The enclosure is executed in the Class I and II appliance protection standard.

Class II appliance protection rating of the enclosure is achieved with an additional insulation layer permanently applied on the internal surfaces of the enclosure. The thickness of the layer ensures the required insulation.

Labyrinth ventilation allows continuous flow of air with simultaneous elimination of penetration of pollutants and accumulation of water and moisture.

The door with internal hinges with anti-burglary lock and multiple bolts, an espag lock with a padlock or a system cylinder.

Installation parts

  • Installation profiles: steel, with openings, installed on the enclosure structure;
  • Installation base: plastic or galvanised steel, installed on vertical installation profiles made of galvanised sheet for current circuit switches;
  • Cable clamps with the cable management bar;
  • Masking panels: made of plastic or sheet metal, installed on the enclosure structure.


  • The primary and backup power supply sources – depending on the power demand. A contactor or motor drive disconnecting switches, additionally fitted with safeguards in the form of fuse switches
    – 20 A to 450 A: power contactors;
    – 40 A to 6300 A: breaker switches and power disconnecting switches;
  • The coupling – to ensure safe switching of the power supply source matching the power performance of the system, with a contactor or motor drive disconnecting switches;
  • SZR transfer switch system – with support for contactors or circuit breakers, ensures automatic switching between the primary and backup power supply sources, returning to the original power supply configuration, setting up any delay and time settings, switching lock to prevent switching on of both sources. The automatics systems employed include PRE (our proprietary module), MA-0A, MSR, MAX, and other. All switching settings correspond with the planned schedules. The delay setting ranges are 0.2–30 s and 20–180 s. The control may be provided automatically or manually.

Current circuits

  • The current circuits with the cross section matching the load (LgY, Cu rail), The PEN busbar with the possibility of PE + N separation


  • Thermosetting foundation block – matching the dimensions of the thermosetting enclosure;
  • FM aluminium foundation block – matching the dimensions of the enclosure, fitted with removable front and back covers;
  • FB concrete foundation block – built of reinforced concrete slabs, screwed with the aluminium or thermosetting enclosure;
  • Cable base.

Basic technical data

  • Rated operational voltage230/400 V
  • Insulation rated voltage690 V
  • Rated frequency50 Hz
  • Impulse withstand voltage8 kV
  • Busbar rated continuous currentup to 4000 A
  • Rated short-time withstand current20 kA (1 s.)
  • Rated peak withstand current40 kA
  • Internal arc short-circuit current16 kA
  • IP protection level44-45
  • IK level of protection against mechanical impact10
  • Appliance classII
  • Dimensions of incoming / outgoing terminals2 x 4 x 240 mm² / 4 x 240 mm²
  • Network arrangementsTN-S, TN-C, TN-C-S, TT, IT
  • Height / width / depthwithout limitations for aluminium enclosures built to Class II protection standard

Compliance with standards

  • PN-EN 61439-1 – „Low-voltage switchgear and controlgear assemblies. Part 1: General rules”;
  • PN-EN 61439-5 – „Low-voltage switchgear and controlgear assemblies – Part 5: Assemblies for power distribution in public networks”;
  • PN-E-05163 – „Enclosed low-voltage switchgear and controlgear assemblies. Guide for testing under conditions of arcing due to internal fault”;
  • PN-EN 50274 – „Low-voltage switchgear and controlgear assemblies – Protection against electric shock – Protection against unintentional direct contact with hazardous live parts”;
  • PN-EN 60529 – „Degrees of protection provided by enclosures (IP Code)”;
  • PN-EN 62208 – „Empty enclosures for low-voltage switchgear and controlgear assemblies – General requirements”;
  • PN-EN 62262 – „Degrees of protection provided by enclosures for electrical equipment against external mechanical impacts (IK code). (IDT PN-EN 50102:2001)”;
  • PN-EN ISO 4628 – „Paints and varnishes – Evaluation of degradation of coatings – Designation of quantity and size of defects, and of intensity of uniform changes in appearance – Part 6: Assessment of degree of chalking by tape method”;
  • PN-EN ISO 2409 – „Paints and varnishes – Cross-cut test”.