On the 4th of June 2007 at 14:00 pm magnetic field measurements were performed for Substation 51 Kolnakos.
The substation is rated at a nominal power of 1000 KVA. At the time when the measurements were performed, the substation load power was recorded as:
|
Red Phase |
Yellow Phase |
Blue Phase |
|
265A |
245A |
255A |
Table 1: Measured load current
The resultant load of all three phases was 18% utilization of the nominal load current.
Limiting exposure values have been provided by the ICNIRP recommendations and are guidelines to many countries and organizations. The exposure limits at 50 Hz are tabulated in the following table according to the limits given by ICNIRP.
|
Reference levels for Occupational exposure ICNIRP |
|||
|
Frequency |
Electric Field Strength, E (V/m) |
Magnetic Field Strength, H (A/m) |
Magnetic Flux Density, B (µT) |
|
50 Hz |
10000 |
400 |
500 |
|
Reference levels for General Public exposure ICNIRP |
|||
|
Frequency |
Electric Field Strength, E (V/m) |
Magnetic Field Strength, H (A/m) |
Magnetic Flux Density, B (µT) |
|
50 Hz |
5000 |
80 |
100 |
Table 2: ICNIRP Exposure limits for Occupational and General Public exposure
The obtained results for the RMS fields inside and outside the substation are shown in tables 3 and 4 respectively. A comparison is also made with the ICNIRP recommendations.
|
Inside Field Measurements |
||||||
|
Distance from Side /m |
Maximum Magnetic Field at Z Height /m - Percentage of ICNIRP General Public Standard /% |
|||||
|
0.3m |
ICNIRP % |
1m |
ICNIRP % |
1.75m |
ICNIRP % |
|
|
0.5m from right side |
48.87 |
9.77% |
54.68 |
10.94% |
43.15 |
8.63% |
|
0.5m from right side |
170.31 |
34.06% |
185.30 |
37.06% |
58.94 |
11.79% |
Table 3: Magnetic Field Measurements inside area
|
Outside Field Measurements |
||||||
|
Distance from Side /m |
Maximum Magnetic Field at Z Height /m - Percentage of ICNIRP General Public Standard /% |
|||||
|
0.3m |
ICNIRP % |
1m |
ICNIRP % |
1.75m |
ICNIRP % |
|
|
0m from Front Side |
8.17 |
8.17% |
12.45 |
12.45% |
4,28 |
4.28% |
|
1m from Front Side |
0.91 |
0.91% |
1.28 |
1.28% |
1.22 |
1.22% |
|
2m from Front Side |
0.39 |
0.38% |
0.38 |
0.38% |
0.36 |
0.36% |
Table 4: Magnetic Field Measurements in the outside area