AS 2344:2016 Limits of electromagnetic interference from overhead a.c. powerlines and high voltage equipment installations in the frequency range 0.15 MHz to 3000 MHz
7 TEST METHODS
The method of test shall be in accordance with CISPR TR 18-2, except that the following shall apply: (a) Measurement frequency At and below 30 MHz，measurements may be made at or near the following frequencies: 0.15 MHz, 0.25 MHz, 0.5 MHz, 1.0 MHz, 1.5 MHz, 3.0 MHz, 6.0 MHz, 10 MHz, 15 MHz and 30 MHz, care being taken to avoid other forms of interference and intentional transmissions provided that the disturbance is broad band only. If the disturbance noise is irregular, the peak and average measured levels at all frequencies shall be recorded and the quasi-peak levels at the 10 highest excursions. At and above 30 MHz only the peak and 10 highest quasi-peak excursions need be recorded.
NOTE: A suitable method for the identification of radio disturbance originating from power equipment, is to monitor the video detector output of the interference measuring set using an oscilloscope with its timebase locked to the powerline frequency and noting the presence of the interference impulses while tuning the receiver. W hen battery-operated equipment is used, a loop antenna, coupled to a broadband operational amplifier, will normally provide an adequate power frequency signal level to externally synchronize the timebase. A more rapid but less conclusive search can be performed by audibly monitoring the measuring set output.
(b) Antena
For measurements below 30 MHz, the antenna shall be an electrically screened square or circular loop enclosing an area of approximately 0.36 m- conforming with AS/NZS 16.1.1 and CISPR TR 18-2. . At frequency ranges from 30 MHz to 1000 MHz，the antenna used shall be a dipole-like antenna designed to measure the E-field, and the free-space antenna factor shall be used.
Where practical, the measurement of overhead powerlines shall be performed at the corridor boundary as shown in Figure 4. If the measurement cannot be made at the corridor boundary the measurement shall be made at another distance and a correction applied using the formula given in Equation 7(1). Measurements are to be taken on both sides of an overhead line. If the measurements at two or more frequencies to the one side are consistently within 3 dB of the other, or are consistently higher to one side, then all measurements may be taken on that one side only.