| 摘要 |
A conductor of a power transmission line has its effective resistance to flow of direct current or low-frequency current (such as, for example, 50 Hz or 60 Hz) varied in a wide range to pass current and/or to generate heat for melting ice. Increasing the initial resistance of a conductor is accomplished by modulating the current at a high frequency (HF), such as about 1 kHz to about 100 kHz. The current through the conductor then becomes a mixture of a DC (or low-frequency current) and a high-frequency current. Because the latter flows in a thin skin-layer region of the conductor of depth dependent on frequency, the conductor's resistance to the HF current is higher than its resistance value for low frequency or DC current. By varying the frequency of current modulation in accordance with the present invention, the conductor's resistance is adjusted to a desired value for ice removal. |
