HD4/R MV gas circuit-breakers for secondary distribution 1 DESCRIPTION 3 2 CIRCUIT-BREAKER SELECTION AND ORDERING 9 3 SPECIFIC PRODUCT CHARACTERISTICS 23 4 OVERALL DIMENSIONS 43 5 ELECTRIC CIRCUIT DIAGRAM 47 1 2 1 DESCRIPTION General information 4 Versions available 4 Application range 4 Protection relay 5 Standards and approvals 6 Service safety 6 Accessories 6 ESH operating mechanism 6 Technical documentation 8 Electrical characteristics 8 Quality Assurance System 8 Environmental Management System 8 Test laboratory 8 3 DESCRIPTION General information HD4/R medium voltage circuit-breakers for indoor installation use sulphur hexafluoride gas (SF6) to extinguish the electric arc and as the insulating medium between the main fixed and moving contacts. They are constructed using the separate pole technique. The operating mechanism is the ESH type with stored energy and trip free with opening and closing operations independent of the operator. Remote control of the circuit-breaker is possible by means of applying special electrical accessories (geared motor, shunt opening release, etc.). The operating mechanism, the three poles and any accessories are mounted on a metallic frame without wheels. Construction is - pact, sturdy and of limited weight. The circuit-breakers in the HD4/R series are maintenance-free “sealed for life” pressure sys- tems (IEC 62271-100 and CEI 71-1 Standards). Versions available HD4/R circuit-breakers are available in the fixed version with right lateral operating mechanism. The circuit-breakers with rated voltage up to 24 kV can be fitted with current sensors and with PR521 microprocessor-based overcurrent release. . In the 24 kV versions with 230 mm pole centre distance, only two current sensors can be mounted (on the lateral poles). Application range The circuit-breakers in the HD4/R series are used in all applications for medium voltage seco