Power distribution line automatic defects detector has electric and magnetic field meters, and logic gates and timers

Power distribution line automatic defects detector

The method involves inductively tapping the current of a mains conductor (10) and capacitatively measuring the voltage across it to evaluate the phase position of the conductor current and voltage and activate corresponding directional indicators (11,12). The phase position is evaluated with an oscillator-controlled counter of a computer (13). The computer determines the cycle duration and the duration of positive voltage input pulses that are produced in the computer with the conductor voltage. The computer accordingly computes the actual zero passage, based on the phase position evaluation.

Indicating direction of energy flow in electric AC voltage mains especially medium voltage mains

A high voltage power supply control device arranged to detect a fault in, disconnect and reconnect a high voltage supply circuit, comprising; a fault passage indicator, a switch to connect or disconnect the supply; a pair of indicator units located on either side of the device to indicate the presence or absence of a fault on their respective sides; and a switch controlled by a control unit so as to only restore power to the side of the device where no fault is detected. Each indicator unit may be able to detect the indication state of adjacent devices and indicator units may be provided between phases of the supply or between a phase and earth. Indicator units may comprise a voltage transformer to which a monitoring signal is applied and may include an earth switch in parallel with the transformer which can be closed in response to fault detection.

Fault detection and restoration system

A short circuit indicator with automatic reset takes its operating current from the high or medium voltage network being monitored. It requires no external energy source. The operating current can be acquired capacitively via field plates (F1, F2) or inductively via several coils. The extracted current is stored in capacitors (C1, C2) or accumulators and the stored energy is used to operate an electromechanical flap indicator. USE/ADVANTAGE - Indicating short circuits in electrical systems, at considerably reduced cost and time.

Short circuit indicator with automatic reset for high and medium voltage networks - takes operating current from monitored network capacitively via field plates or inductively via coils

The invention relates to short-circuit direction indicators for high-voltage lines fed from two ends in three-phase systems. In such devices, it is usual to use a capacitive sensor for the voltage and an inductive sensor for the current and to transfer the sinusoidal quantities via Zener diodes in trapezoidal form. It is the object of the invention to improve known devices by simple means in such a manner that they still reliably indicate even with a collapse of the voltage in the short-circuit case. This is achieved by the fact that the star or delta voltage triggers a synchronous oscillator (2) which continues to run with the correct phase in the short-circuit case and is used as phase frequency, that the signals (U20, U21) of the sensors (1, 3) are supplied to a drive logic (4) and that the drive logic (4) output is connected to a phase measuring unit (6) consisting of logic gates, the output of which feeds direction indicating elements (LED1, LED2).

Horstmann Hendrik Dipl Ing

Papers

Short-circuit direction indicators