BS IEC 61892-1:2015 pdf download-Mobile and fixed offshore units — Electrical installations Part 1: General requirements and conditions.
4.6 Power supply system characteristics 4.6.1 General Unless otherwise stated in other parts of this standard, the equipment shall function when supplied from general distribution systems with due regard to voltage and frequency variations, harmonic distortion and conducted disturbances. The characteristics of general distribution systems are given in the following subclauses. Where the power supply is obtained from the shore, due regard should be paid to the effect that the quality of the supply, if different from that specified in this clause, may have on the performance of equipment. For systems where semiconductors are connected having a total rating which is a significant portion of the total system rating, it may be feasible to suppress the harmonics. Consideration should be given to taking appropriate measures to attenuate these effects of the distribution system so that safe operation is assured. Care should be taken in selecting consumers supplied from an electric power supply system with a higher harmonic content than specified in this clause. Electrical equipment which requires a higher quality power supply may need additional provisions to be made locally. Where additional equipment is fitted to achieve this higher quality power supply, it may be required to be duplicated and segregated to the same degree as the electrical equipment it supplies. Special attention should be paid to the installation of electrical equipment which may influence the quality of power supply on a local basis or react with any harmonics present on the general distribution system. Variable frequency/voltage systems may be admissible provided safe operation of the system is assured and equipment is suitably rated for the expected variations.
4.6.2 AC distribution systems 4.6.2.1 General The voltages referred to in 4.6.2.2 are measured at the point where the equipment is installed. Electric motors are normally designed for a combination of voltage and frequency variations which is less than the combined limits given in this clause. For combined voltage and frequency variations for electric motors, reference is made to IEC 60034-1 . 4.6.2.2 Voltage characteristics Requirements to voltage characteristics are given in Table 3. Tolerances are expressed in a percentage of the nominal voltage.