BS EN 61587-3-2013 pdf download.Mechanical structures for electronic equipment Tests for IEC 60917 and IEC 60297 Part 3: Electromagnetic shielding performance tests for cabinets and subracks.
3.1 Electromagnetic shielding performance tests for cabinets and subracks
Various levels of shielding performance can be achieved depending upon the construction of the cabinet or subrack. Although shielding performance measurements are of limited value in predicting the final overall system performance, consistent measurement techniques are vital to ensure any measure of repeatability. The aim of this standard is to provide comparable shielding performance testing results from one test laboratory to another (see IEC 61000-4-3), The test result is valid only for cabinets or subracks determined by equal dimensions and contents, for example removable covers, door. etc. The standard should be used for the evaluation of design variations.
3.2 Test condition
All testing shall be performed In a semi-anechoic or full anechoic chamber or open field test site as illustrated in the figures. When the semi-anechoic chamber or the open field test site is used, the chamber shall meet the vertical and horizontal site attenuation test described in CISPR 16-1. For the test set-up in the open field or an anechoic chamber, see Figures 3 to 8.
3.3 Test configuration
3.3.1 CalIbration of the reference antenna
The purpose of calibration Is to check the characteristics of the reference antenna, which is
the output level of a transmitting antenna and the sensitivity level of a receiving antenna.
The test shall be performed by setting the transmitting antenna facing the receiving antenna.
The direction of the transmitting antenna is at 0 and the radiated field strength is maximum. The height of the transmitting antenna shall be set at 1,1 m.
The receiving antenna shall be positioned I m high and 3 m in distance from the transmitting antenna. The frequency is 100 MHz and 500 MHz.
Calibration shall be made using both horizontal and vertical antenna polarities.
3.3.2 Transmitting antenna
The transmitting source shall be a Spherical Dipole Antenna (SDA) see Annex A or similar (see Note 1 in Table 1). The size of the transmitting antenna should be equal or smaller than 150 mm in diameter. The equivalency to the SDA should be evaluated by an analysis of the radiation pattern of the alternative antenna. Annex A illustrates the application of a spherical dipole antenna (SDA). It is necessary to confirm whether sufficient power level of the transmittino antenna can be ensured.
The transmitting antenna should be connected to the sender equipment located In outside of the test specimen without affecting the shielding integrity of the test specimen.
The distance of the transmitting antenna to the metal wall of the enclosure should be at least the diameter of the spherical antenna. The dynamic range of the measuring equipment should be determined with the appropriate level above the expected attenuation level as shown in Table 1.
3.3.3 ReceivIng antenna
The receiving antenna shall be one of the following types:
— 30 MHz to 200(300) MHz biconical antenna;
— 200(300) MHz to 1 000 MHz log periodic antenna.
The change from biconical to the log periodic may be at 200 MHz or 300 MHz (see Note 1 in Table 1).
Alternatively, a combined biconical/logarithmic-periodic antenna for the whole frequency range up to 1 000 MHz may be used.
For the frequency range 1 000 MHz to 3 000 MHz, horn antennas should be used.
3.3.4 Reference measurement
Reference measurements E1 (dBjiV) are made without the test specimen. The transmitting antenna shall be placed at the position in which it will be once the test specimen is present. The transmitting antenna shall be positioned at 3 m distance from the receiving antenna and the two antennas shall face each other in the same direction as that of the calibration.
Measurements shall use both horizontal and vertical polarities. Transmitting and receiving antenna shall be polarized in the same manner. Frequency sweeps shall be in Increments of not greater than 5 MHz between 30 MHz and 3 000 MHz. The receiving antenna shall be swept through heights of I m to 4 m. The greatest signal strength E1 for each frequency shall be recorded (see Figures 3 and 6).
3.3.5 TransmItting antenna set-up
The transmitting antenna shall be placed in the centre inside the test specimen in the same direction as that of the reference measurement and suspended by non-conductive material (see Note I in Table 1).
3.3.6 Test specimen set-up
In the case of a floor-standing cabinet, there shall be an insulation between the cabinet and the reference plane of the chamber of 100 mm (±5 %). A table top test specimen shall be placed at a height of 800 mm (±5 %) from the reference plane.
3.4 Test requirements
Measurements shall be made by using both horizontal and vertical antenna polarities. Both transmitting and receiving antennas shall be polarized in the same manner. Frequency increment measurements shall be made.
The equipment under test shall be rotated 360° through its vertical axis (via a turntable or other means) and the maximum signal strength determined in increments of 90°, i.e. a minimum of four reading points in the frequency range of 30 MHz to 200(300) MHz. 45° in the frequency range of 200(300) MHz to 1 000 MHz and 30° in the frequency range of 1 000 MHz to 3 000 MHz.
Frequency sweeps shall be made in increments of not greater than 5 MHz between 30 MHz and 3 000 MHz. The receiving antenna shall be swept through heights of I m to 4 m. The greatest signal strength E2 (dBj.aV) from the combined sweep of the turntable and antenna height shall be recorded for each frequency. For the typical test equipment configuration, see Figure 1.BS EN 61587-3-2013 pdf download.