1.1 This standard prescribes standard frequencies required for special control applications required for single phase and three phase ac systems for installation in ships, for ac traction systems, machine tools, rayon industry and aircraft. This standard is limited to frequencies up to 10 000 Hz.
1.2 The standard frequencies for centralized control installations are not covered in this standard.
IS 7691-1975 history
1975IS 7691-1975 Frequencies for special power applications