A system and method for detecting partial discharge of gas-insulated switchgear wherein a high-frequency component and the fundamental wave component of the voltage applied to the conductor of the gas-insulated switchgear are detected, the zero-cross point of the fundamental wave component is set as the starting point for the voltage, and the presence of partial discharge and the reason for the occurrence of partial discharge are ascertained based on the phase difference between the phase of the detected high-frequency component and the phase of the starting point of the voltage.

System and method for detecting partial discharge of gas-insulated switchgear

The present invention provides a method and device for detecting a discharge in an electrical device comprising, providing a bushing having a bottom lower flange and a top upper flange, providing a shield inside the bushing extending from the bottom lower flange to a position at least below the top upper flange and providing an antenna outside the bushing at least above the position for measuring an output signal from the device for detecting the discharge.

Method and device for detecting a partial discharge in an electrical device

A method for detecting a high pressure condition within a high voltage vacuum device includes detecting the position of a movable structure such as a bellows. The position at high pressures can be detected optically by the interruption of a light beam reflected by a hemispherically shaped reflector. The hemispherical reflector allows the source light fiber to oriented parallel to the detection light fiber, providing a more compact and efficient fiber routing.

Method and apparatus for the detection of high pressure conditions in a vacuum-type electrical device

A power use circuit breaker includes an arc generating switching unit which adds an electrical resistance in a circuit during current interruption to attenuate a current to be interrupted, a vacuum bulb which is electrically connected in series with the arc generating switching unit and interrupts the attenuated current and a current conducting switching unit connected in parallel with the series circuit of the vacuum bulb and the arc generating switching unit. For current conduction the current conducting switching unit is closed after the vacuum bulb and the arc generating switching unit are closed, and for current interruption after opening the current conducting switching unit, the vacuum bulb and the arc generating switching unit are opened.

Power use circuit breaker and electrical circuit arrangement for electric power generation plant

Vacuum presence monitoring is a routine maintenance procedure carried out on vacuum circuit breakers, in which the CB is isolated from the electrical network. The presence of the vacuum is verified by applying a voltage across the open contacts of the vacuum interrupters VI's higher than the breakdown voltage of such contacts in air. This procedure has a 50 years proven record and has found world wide acceptance. Today other methods are proposed to monitor the vacuum presence. These methods can be divided in 3 additional classes discriminated by the pressure range in which they are active. Each class has a clear advantage not shared by the others. Vacuum pressure monitors using high vacuum pressure gauges can give an early warning of an upcoming failure. Monitors using low vacuum pressure gauges detect the dielectric failure caused by vacuum loss as it comes. Monitors using barometric gauges clearly indicate the end of life of the VI. Today only these 3 systems can be used to monitor the pressure in a continuous way. The continuous vacuum monitor significantly decreases the probability to operate a VCB with a leaky VI, hence increasing the availability of the VI on the VCB for the network operator to 99.9999%. The continuous vacuum monitor based on low pressure vacuum gauges is considered an optimal engineering choice as it does not impact the design of the VI.

Continuous vacuum monitoring in vacuum circuit breakers

An abnormally high vacuum pressure of a vacuum interrupter is detected from outside of the interrupter in response to electromagnetic wave signals generated by an electric discharge derived in response to a voltage difference and depending upon Paschen's law. Since the above-mentioned electric discharge is quite different from so-called partial discharge, even when the fixed and movable contacts are closed (i.e., under hot-line condition), it is possible to detect poor vacuum pressure on the basis of the electric discharge existing between the fixed and movable contact rods including two contacts and the main shield, as well as when the two contacts are open. The vacuum monitor according to the present invention comprises a rod or loop antenna fixedly or movably disposed near a conductive material of or connected to the vacuum interrupter and a detection section including, in particular, a 2 to 20 KHz band-pass filter.

Vacuum monitor device and method for vacuum interrupter

A vacuum monitor for a vacuum interrupter which can detect a poor vacuum pressure from the outside of the interrupter on the basis of the electromagnetic wave signals generated by the electric discharge existing in accordance with a prebreakdown voltage depending upon Pashen's law when vacuum pressure increases within the vacuum interrupter. Since the above-mentioned electric discharge is quite different from so-called partial discharge, even when the fixed and movable contacts are kept closed (i.e. under hot-like condition), it is possible to detect poor vacuum pressure on the basis of the electric discharge existing between the fixed (8) and movable (9) contact rods including two contacts (10, 13) and the main shield (16), as well as when the two contact are kept opened. The vacuum monitor according to the present invention comprises a rod or loop antenna (21) fixedly or movably disposed near a conductive material of or connected to the vacuum interrupter and a detection section (20) including, in particular, a 2 to 20 kHz band-pass filter (24).

Masayuki Sakaki

Papers

Vacuum monitor device and method for vacuum interrupter

Vacuum monitor for vacuum interrupter and use of the vacuum monitor