CECS: 6694 Calculation procedure for the protection distance between AC high voltage overhead transmission lines and short wave radio direction finding stations and receiving stations CECS66:94 CECS:6694 standard download decompression password: www.bzxz.net

CECS66-94
China Engineering Construction Standardization Association Standard
The calcuating method of protecting distance for AC highvoltage overhead power transmission lines to shortwave
radio direction finding stations (stations) and receiving stations (stations)
Shortwave radio direction finding stations and receiving stations China Engineering Standardization Association Standard
Calculation Procedure for the Protection Distance between AC High Voltage Overhead Transmission Lines and Shortwave
Radio Direction Finding Stations and Receiving Stations
CECS66:94
Editor: Electromagnetic Interference Subcommittee of Electrical Engineering Committee of China Engineering Standardization Association
Approval Department: China Engineering Standardization Association Approval Date: December 13, 1994
The Calculation Procedure for the Protection Distance between AC High Voltage Overhead Transmission Lines and Shortwave Radio Direction Finding Stations and Receiving Stations CECS66:94 is now approved as the China Engineering Standardization Association Standard for use by relevant units. During use, please send your comments and relevant information to the Electrical Engineering Committee of China Engineering Standardization Association, Power Construction Research Institute of Ministry of Electric Power, Liangxiang, Beijing (Postal Code 102401) for reference during revision. China Association for Standardization of Engineering Construction
December 13, 1994
Nouns and terms
General provisions
Calculation of protection distance.
Passive interference to shortwave radio direction-finding stations (stations) 4.1
Calculation of protection distance
Calculation of protection distance for active interference to shortwave radio direction-finding stations (stations) and receiving stations (stations)
Determination of protection distance
Additional notes
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1 General
1.0.1. This standard specifies the calculation method for the protection distance of AC high-voltage overhead transmission lines to shortwave radio direction-finding stations (stations) and receiving stations (stations). 1.0.2 This standard applies to the calculation of the protective distance between 110-500kV AC overhead transmission lines and fixed radio measuring stations (stations) and receiving stations (stations) with an operating frequency of 1.5-30MHz.
1.0.3 Related standards
GB13614-Electromagnetic environment requirements for short-wave radio direction-finding stations (stations) GB13617-Electromagnetic environment requirements for short-wave radio receiving stations (stations) GB7349-Measurement methods for radio interference of high-voltage overhead transmission lines and substations 5
2 Nouns and terms
2.0.1 Radio direction-finding station (station)
A facility that uses radio means to determine the direction of radio transmitters and other radiation sources.
2.0.2 Passive interference
An obstacle near the radio direction-finding antenna that can re-radiate or reflect electromagnetic waves and affect the accuracy of direction-finding.
2.0.3 Active interference
Various external electromagnetic radiations that cause radio interference to radio direction finding and reception. 2.0.4 Protection distance
The minimum distance between active interference sources and passive interference objects and the front edge of the antenna of the shortwave radio direction finding station (station) and the receiving station (station) to ensure the normal operation of the shortwave radio direction finding station (station) and the receiving station (station). 2.0.5 Transmitter power
The maximum nominal output power of the transmitter under various working conditions. 6
3 General provisions
3.0.1. The azimuth error value of shortwave radio direction finding caused by passive interference objects such as AC high-voltage overhead transmission line towers shall not exceed 1°. 3.0.2 The increase in environmental (background) noise caused by radio interference from AC high-voltage overhead transmission lines shall not exceed 0.5 dB for shortwave radio direction-finding stations (stations) and first-level shortwave radio receiving stations (stations); shall not exceed 1 dB for second-level radio receiving stations (stations); and shall not exceed 1.5 dB for third-level radio receiving stations (stations). 7
4 Calculation of protection distance
4.1 Calculation of protection distance for passive interference of shortwave radio direction-finding stations (stations) 4.1.1 Calculation for single tower
The maximum error of radio direction-finding caused by a single tower is: 48m=(180/yuan)(La/D)
Where:
49ma-maximum error caused by tower ()La-height of tower, m;
D-distance between tower and direction-finding antenna, m. (4.1.1-1)
According to 3.0.1, △0m shall not exceed 1, then the calculation formula of protection distance is: D≥(180/yuan)La
4.1.2 Calculation considering the influence of adjacent towers (4.1.1-2)
4.1.2.1 When the towers are arranged in a straight line, increase the multiple of protection distance according to Table 1 (middle of the range, linear interpolation).
Increase protection distance multiple tablebZxz.net
S(pole distance)/La(pole height)
10—15
Multiples required for single tower
4.1.2.2 When the towers are arranged irregularly (e.g. Figure 4.1.2), the error value generated by each tower should be calculated one by one on both sides, starting from the tower closest to the direction finding station 8
(station) antenna, until the error generated by the nth (or) tower is less than one fifth of 480, that is: 48m (40m) <4 60/5
Then take the square sum root of each error value
45=［460+
(4,1.2-1)
(4.1.2—2)
And take the root mean square value (half of the maximum value) according to the possible 360-degree azimuth of the re-radiated wave and the possible 2-element range of the phase difference with the main wave 4=40/2
This standard stipulates that when the protection spacing requirements are met, it must be 48m≤1
AC high voltage
overhead power transmission
line tower
(4. 1.2 — 3)
(4. 1. 2 - 4)
Direction finding station antenna
4.1.3 The attenuation of electromagnetic waves propagating along the ground increases with the increase of frequency. This standard stipulates that when the minimum frequency actually used by the shortwave radio direction finding station is 5MHz, the protection distance value calculated above can be reduced by 30%. The minimum operating frequency is between 1.5-5MHz, and the value is obtained by linear interpolation. 9
4.2 Calculation of active interference protection distance for shortwave radio direction-finding stations (stations) and receiving stations (stations)
4.2.1, Calculation formula for protection distance
This standard adopts the control environment (background) noise calculation method, that is, the protection distance is calculated by allowing the increment of the background noise field strength, and the lateral propagation attenuation value per time is 10dB within 100m and 6dB beyond 100m. The calculation formula for protection distance is: D = 10(CBoNeg(100. 16W-1)23)/20+2)(4.2.1)
D Protection distance, m,
Eo-the converted interference field strength of the radio interference reference field strength of the AC high-voltage overhead transmission line at the actual working frequency and rainy conditions, dB (uV/m),
No-environmental (background) noise field strength, dB (uV/m): N-the allowable increase in environmental (background) noise field strength, dB. 4.2.2 The reference field strength of radio interference of AC high-voltage transmission lines The reference field strength refers to the interference field strength at a frequency of 0.5MHz and 20m away from the phase conductor of the transmission line under sunny conditions, which can be determined by one of the following methods. 4.2.2.1 Take the value according to the limit values ​​stipulated by relevant national regulations. 4.2.2.2 After measures are taken to reduce the radio interference field strength of the AC high-voltage transmission line, the value of the radio interference reference field strength obtained by actual measurement can be taken. 4.2.2.3 Calculate according to the relevant formula
（1）The reference radio interference field strength of each phase conductor Eos=3.5gms（a）+12r-30-331g（Da/20）Eos=3.5gmor（6）+12r-30-33lg（Db/20）Eo=3.5gm(c）+12r-30-331g(Dc/20)(4.2.2-1)
Eo, Eob, Eo The reference radio interference field strength of each phase conductor, dB（uV/10
Da, Db, Dc, A, B, C relative to the side line 20m, m; gmx—the maximum potential gradient on the conductor surface, kV/cm,r conductor radius, cm.
(2) If the radio interference level of one phase conductor is 3 dB greater than the radio interference field strength of the other two phase conductors, the radio interference reference level of the three-phase conductor of the AC high-voltage overhead transmission line is Emx, otherwise it is:
(4.2.2-2)
Radio interference reference field strength of the three-phase conductor of the AC high-voltage overhead transmission line, dB (uV/m);
E-the maximum value of the radio interference field strength of each phase conductor, dB (μV/m);
(3) For AC high-voltage overhead transmission lines, the radio interference field strength of each phase conductor can also be simplified to ：
E=3.5g+12m-30
(4.2.2-3）
The radio interference reference field strength of the three-phase conductors of the AC high-voltage overhead transmission line is: E=E+1.5
(4.2.2-4)
The interference reference E
quasi-field strength of the three-phase conductors of the AC high-voltage overhead transmission line, dB (μV/m),
E-AC high-voltage overhead transmission line, the interference field strength of each phase conductor dB (μV/m);
4.2.3 The radio interference reference field strength on rainy days should be increased by 15dB compared to sunny days. 4.2.4 Frequency characteristics of radio interference of AC high-voltage overhead transmission lines The frequency characteristics of radio interference refer to the relationship between the correction value of the radio interference field strength and the frequency
4B=5(1-2(1g10f)}
(4. 2. 4)
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