The name Calor comes from the Latin Word for heat, corresponding to the response criterion of these protection switches. During this initial period, high- and medium-voltage switchgear was built in the Emag works, which took its name from the Elektrische Meßinstrumente -und Apparatebau-Gesellschaft (Electrical measuring Instrument and apparatus company).
Within a few years only, the young CALOR-EMAG was manufacturing a well-rounded range of products for customers in heavy industry, the basic chemicals sector, and power supply. Exports in the prewar period, however, remained within modest limits. Nevertheless, at the outbreak of war in 1939, CALOR-EMAG was employing a staff of over 1,500. The extensive destruction of the works meant that reconstruction after 1945 was a slow process.
Deliberations on minimum-oil circuit-breakers from before the war were taken up again. In 1949, the first circuit-breakers on this principle went into series production, and from then on, success of CALOR-EMAG was closely coupled with advances in circuit-breaker construction.
Together with the development of circuit-breakers, the 1950s saw the start of another test program, which was to have extremely far-reaching consequences:
- CALOR-EMAG was the first manufacturer systematically to concern itself with the effects of arcing in high-voltage switchgear installations. The result - new switchboard versions for operating voltages of up to 35 kilovolts (kV) in metalclad design with withdrawable circuit-breakers - was a Iandmark in switchgear design.
- The world's fastest switching device - the Is-Iimiter - for handling of high short-circuit currents, the first SF6 insulated high-voltage switchgear installation in the world, and switchgear cubicle designs for a variety of special applications (including both underground and open cast mining) were further milestones on the company's road to success.
Following a lively exchange of theoretical knowledge and experience with Brown, Boveri and Cie AG, the entire block of shares was purchased in 1973 and CALOR-EMAG thus integrated into the BBC Group.