Abstract: An overhead electrical power and optical transmission system, comprising overhead electrical phase conductors (2) extending between and supported by towers (10), and at least one optical cable (1) that extends between and is supported by, the towers. Each optical cable has a resistive element (12) that is removably supported thereby and which extends from a tower (10) where it is earthed part of the way along the span of the optical cable, and the resistive element has the necessary length and conductivity such that if a dry band (6) occurs on the cable at the end of the element, the potential difference (VG') across the band is insufficient to form an arc, such that any induced current is insufficient to sustain any arc that may occur across the dry band.

Abstract: A device for testing an electrical line by time domain reflectometry, using a pulse generator to generate a series of test pulses, a programmable delay generator which provides a delay in the transmission of the test pulses, and an analog to digital converter which samples the reflected signals from the line and sends them to memory. The test pulse is transmitted to the line and a number of digital sample values are produced sequentially at a defined sampling rate by the delay generator, which is incremented or decremented to advance or retard the transmission of the test pulse by 1/n times the sampling period, and sample values from each pulse obtained. The above steps are repeated until transmission of the test pulse has been retarded or advanced by at least (n-1)/n times the sampling period and sample values from each pulse obtained, with the sampled values arranged in order of increasing time difference between transmission of the test pulse and sampling.

Abstract: A bootstrap circuit comprising an inverter for inverting an input signal from an input node, a delay stage for delaying the input signal from the input node for a predetermined time period, a first capacitor connected between an output terminal of the inverter and a junction node, a first NMOS transistor for transferring the input signal delayed by the delay stage to the junction node, the first NMOS transistor having a drain connected to an output terminal of the delay stage, a source connected to the junction node and a gate connected to a supply voltage source, a second capacitor connected between an output node and a ground voltage source, and a second NMOS transistor for transferring the input signal inverted by the inverter to the second capacitor connected to the output node in response to a signal charged on the first capacitor. According to the present invention, the bootstrap circuit bootstraps the input signal to a high voltage level at a high speed.