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RF readings at 5 metre distance from various sources

In document RF radiation readings (W/m2) (halaman 63-66)

RF radiation readings (W/m2)

4.4 RF readings at 5 metre distance from various sources

Table 4.4: First batch of RF radiation readings from various sources

RF radiation readings (W/m2)

Smart Meters Traditional Meters Others SGM 3031 Sprint/MK29

TNB meter Sub Station Overhead line /Metronix

5 meter 5 meter 5 meter 5 meter 5 meter

0.0015 0.00083 0.000057 0.000145 0.000083

Figure 4.4: Bar chart of RF radiation readings versus types of energy meters and other various sources

5 meter 5 meter 5 meter 5 meter 5 meter


SGM 3031 Sprint/MK29 TNB meter Sub Station Overhead line

Smart Meters Traditional Meters Others

RF radiation readings (W/m2)

As the distance between sources increases to 5 metres away, it is predicted that the RF power intensity will further reduce. Once again, the background RF for this set of data will be the average between the traditional meter and the overhead line which equals to 0.00007 W/m2. Both readings only differ by 37.14% difference which is less than 38%. However, the smart substation yields 140.51% times less than the group of smart meters and 164.74% times less than SGM 3031. As observed from the distance of 1 metre, the percentage difference obtained was at most 38% off than either of the smart meter RF readings. Hence, in this situation the percentage difference increased to exactly 6 times less compared to the initial 1-meter distance reading. This means that the RF reading at 3 metres should be approximately three times less in terms of magnitude compared to the 1-meter distance magnitude.

In certain ways, it brings more pro than cons. RF fields decrease drastically at certain distances and based on the readings obtained, 5 metres radius from the smart substation to the nearest residential house will be the best option as RF fields drops to about ten times less than the RF from smart meters. Other unforeseen factors are the presence of underground cables originating from substations to the residential houses (How to measure EMFs from powerlines…, 2005). Directly perpendicular upwards from this cable will yield high magnitudes of EMF readings. This could constructively add up to the RF field at 1-meter distance from substation thus providing the magnitude of 0.0025 W/m2. On the other hand, an engineer from TNB did replied me to confirm that there is a RF communication tower in the smart substation itself, hence that reading is acceptable and justified.

Both RF measured for SGM 3031 and the group of three smart meters differ in terms of percentage of 57.51%. That is once more less than 58%, thus the magnitude is somewhat accurate. Now, a second batch of readings are obtained. Similar like the other two distances earlier, similar method is used. SGM 3031 yields 0.00154 W/m2 while the group of smart meters yield 0.00114 W/m2. Both readings differ by a small percentage of 2.63% which is very accurate for SGM 3031 and the other readings differ by 31.47% which is also less than 32% difference. The average value between both batches can be calculated to be 0.00152 W/m2 and 0.000985 W/m2. Therefore, the percentage difference between both SGM 3031 and the group of three smart meters now measures at 42.71% difference which is again less than 43%.

Next, for SGM 3031 smart meter, a reduction of about 60% is observed for the decrease of RF intensity when the distance increased to 3 metres and just a mere 1%

drop when the distance increases to 5 metres. As for the group of three smart meters, a decrease of 18% is observed at 3 metres distance away and just a mere additional 1%

drop recorded at 5 meters away. However, there is an outlier where the RF strength for traditional meter was higher by 110% at 3 metres away but less by 160% at 5 meters away from the source. This clearly indicates that traditional meter does not produce RF radiation at all as these readings originates from the background and surrounding RF radiation.

In terms of the smart substation, since the RF measurements cannot be executed at 3 meters’ distance from source, thus a comparison will be done between the readings of 1 meter away and at 5 meter away. The average reading for 1 meter away from source is 0.0022 W/m2 and the reading for 5 meter away is 0.000145 W/m2. Hence, from both readings, it is found that the power intensity decreases about 15.17 times less when the RF reaches the 5-meter mark. According to the inverse square law, the power intensity of radiation will decrease one fourth the magnitude when the distance is doubled from the point of radiation. Thus, this rule can be applied to RF propagation. As 5-meter mark lies just after four times the distance, thus the power intensity of RF should decrease slightly more than one eight of the magnitude.

By using the formula of inverse square law as shown below, more precise value can be obtained in order to calculate the exact magnitude of intensity at 5 metre

𝐼2= RF power intensity (W/m2) at final distance intended of 5 meter 𝑋12= Distance in meter of initial intensity

𝑋22= Distance in meter of final intensity

Hence, by substituting the appropriate values, the theoretical value for the supposed power intensity at 5 meters is calculated to be equals to 0.000088 W/m2.

0.0022 𝐼2 = 52

12, 𝐼2 = 0.000088

Then, the ratio between the theoretical value and the measured value is calculated in order to obtain the percentage difference which equals to 48.93%. This is still below the acceptable range because there are other external factors taken into consideration like cumulative RF interference from background RF waves. Besides that, the point source of RF radiation located at the peak of the tower at the substation is high up from ground level. Hence, the surface area of RF waves when reaches the RF meter will be very large thus the intensity of RF will decrease significantly.

In document RF radiation readings (W/m2) (halaman 63-66)