1、I CCITT VOLUME*LX 8% = 48b2591 0550727 b = Note - The Directives concerning the protection of telecommunication lines against harmful effects from electric power and electrijed railway lines mention a limit of 60 V for the voltage induced into telecommunication lines. This limit of 60 V concerns onl
2、y the safety of personnel and should not be taken to be a limit for the purpose of ensuring that there is no interference to signalling systems. In the case of unbalanced signalling systems, such interference may be caused by much lower voltages, as is mentioned in 2. Administrations that wish to ad
3、opt joint use of the same supports for open-wire or aerial cable telecommunication lines and for electricity lines are recommended, when national laws and regulations permit such an arrangement, to take the following general considerations into account: 1) There are economic and aesthetic advantages
4、 to be derived from the joint use of poles by Administrations and electricity authorities. 2) When suitable joint construction methods are used, there is, nevertheless, some increased likelihood of danger by comparison with ordinary construction methods, both to staff working on the telecommuni- cat
5、ion line and to the telecommunication installation connected thereto. Special training of personnel working on such lines is highly desirable and especially when the electricity line is a high-voltage line. The rules given in the Directives in connection with danger, disturbance, and staff safety sh
6、ould be complied with (see i). Special formal agreements are desirable between the Administration and the electricity authority in the case of joint use of poles in order to define responsibilities. If joint use is applied on short sections (of the order of 1 km), in most cases a few simple precauti
7、ons may be enough to ensure that disturbances due to electric and magnetic induction are tolerable. 1 3) 4) 5) References CC1- manual Directives concerning the protection of telecommunication lines against harmful effects from electric power and electrified railway lines, Vol. IX, ITU, Geneva, 1988.
8、 11 2 Ibid., Vol. VI. Recommendation K.5 JOINT USE OF POLES FOR ELECTRICITY DISTRIBUTION AND FOR TELECOMMUNICATIONS (Geneva, 1964) Reference CCIT manual Directives concerning the protection of telecommunication lines against harmful effects from electric power and electrijed railway lines, Vol. II,
9、ITU, Geneva, 1988. 11 Recommendation K.6 PRECAUTIONS AT CROSSINGS (Geneva, 1964) Introduction Crossings between overhead telecommunication lines and electricity lines present dangers for persons and for equipment. A number of arrangements have been made by the responsible authorities in various countries, resulting in national regulations. These regulations are sometimes rather inconsistent and the effectiveness of the arrangements made varies somewhat. Volume IX - Rec. K.6
