Select VLF Series Tester of appropriate specifications according to the subjects
Release Time : 2020-12-30 View Count : 次When in use, the capacitance of the test object shall not exceed the rated capacitance of the instrument. If the capacitance of the test object is too small, the output waveform will be affected. If it is less than 0.05 μ F, the instrument will not output normally. At this time, 0.05 μ f capacitor (provided by the company) can be connected in parallel for auxiliary output. See Table 1 and table 2 for the estimation of capacitance of common electrical equipment.
Table 1 single phase earth capacity of different types of generators.
Steam turbine generator | Hydro generator | ||||||
Capacity （MW） | 200 | 300 | 600 | 85 | 125-150 | 300 | 400 |
Single phase ground capacitance(uF） | 0.198 | 0.18-0.26 | 0.31-0.34 | 0.69 | 1.8-1.9 | 1.7-2.5 | 2.0-2.5 |
Table 2 capacitance of XLPE insulated single core power cable (μ f / km)
Voltage(KV) capacitance (uf/Km) Cross-sectional area（mm） | 16 | 25 | 35 | 50 | 70 | 95 | 120 | 150 | 185 | 240 |
10 | 0.15 | 0.17 | 0.18 | 0.19 | 0.21 | 0.24 | 0.26 | 0.28 | 0.32 | 0.38 |
35 | — | — | — | 0.11 | 0.12 | 0.13 | 0.14 | 0.15 | 0.16 | 0.17 |
Estimation method of test object current:
Calculation formula: I = 2 π FCU
