Abstract: A circuit improvement and method leading to increased leak detection sensitivity is provided for gaseous leak detectors which utilize a hand held probe. The circuit modification provides a high pass filter and additional circuit gain which are switched together in or out of the detection circuit. When the modification is switched in circuit it is necessary to move the probe with a sweeping motion while searching for a gaseous leak.

Abstract: A pulsed discharge helium ionization detector set forth and comprises an elongate cylindrical body having an axially flow path. A helium source is connected to deliver helium flowing along this path. At some location in the helium flow path, transversely positioned, facing electrodes are located. When provided with pulses discharged across the helium flow path wherein the discharge is either monopolar or bipolar pulses, the spark interacts with the helium to create photon ionization. Downstream within view of the spark, a counter flow sample injection tube is positioned to deliver samples at a reduced flow rate. The sample is swept back along the helium flow path past a pair of electrode rings spaced along the flow path. The interaction of the photon ionization with the sample creates a current which can be detected by an electrometer across the two terminals.

Abstract: A spark detection apparatus is set forth and incorporates a closed chamber for receiving a carrier gas flowing therethrough between inlets and outlets, and the carrier gas is exposed to a pair of electrodes forming a spark across the chamber and through the carrier gas. One component of the carrier gas is argon. The sample to be analyzed is injected into the carrier gas. One reaction involves the formation of metastable argon which upon decay serves as a source of ionizing radiation which reacts with sample compounds producing detectable events. These events are used to identify and quantify unknown compounds contained in the sample. The methods and apparatus are especially useful in measuring pollutant compounds in atmospheric samples since the ionizing radiation emitted from the decay of metastable argon is below the ionization potential of the major constituents of air. This greatly enhances the signal-to-noise ratio for detecting impurity compounds when the detection system is used to monitor air quality.

Abstract: A pulsed discharge helium photon ionization detector comprises an elongate cylindrical body having an axial flow path. A helium source is connected to deliver helium flowing along this path. In the helium flow path, transversely positioned, facing electrodes are located to form a spark discharged across the helium flow path wherein the spark interacts with the helium to cause photon ionization. Downstream within view of the spark, a counter flow dopant gas injection tube is positioned to deliver dopant at a reduced flow rate. The dopant is swept back along the helium flow path past a set of electrode rings spaced along the flow path. The interaction of the photon ionization with the dopant creates a base current which can be detected by an electrometer across the terminals. A sample injection tube adds an eluted GC column sample or peak which changes the base current so that eluted sample is measured.

Abstract: An improved corona discharge detection probe, including a corona discharge gas detector, the detector including electronic circuitry, a cathode electrode, an anode electrode spaced from the cathode electrode, and a mechanism for constraining through the probe the flow of atmospheric air to be sensed. The probe has a tip for initially receiving the flow of atmospheric air to be sensed. An external chamber is included, the external chamber being securable to the tip of the detector probe. An adsorbent material is placed within the external chamber about the detector probe such that ambient atmosphere first flows through the chamber prior to encountering the probe tip. The adsorbent material acts to adsorb water vapor in a controlled manner, such that changes in the water vapor level do not affect the detection probe circuitry and thereby eliminates false alarms.

Abstract: A photoreceptor charging device, already provided in an electrophotographic printing machine, is used to determine the voltage potential of a portion of the photoreceptor located adjacent to the photoreceptor charging device. In particular, an operating condition of the photoreceptor charging device, such as, for example, the total current supplied to a coronode and to a grid of the photoreceptor charging device, or the voltage potential of the grid of the photoreceptor charging device when the total current is a predetermined, relatively small value, is used to determine the voltage potential of the photoreceptor adjacent to the charging device.

Abstract: A refrigerant gas leak detector for detecting the location of leaks of refrigerant gas such as halogen has a sensing tip with a pair of electrodes across which a relatively high voltage is generated to cause a corona current to pass through the electrodes. The voltage applied across the electrodes is varied to maintain the corona current through the electrodes at a substantially constant magnitude. The leak detector includes a gas sensing circuit that detects changes in the concentration of refrigerant gas by sensing the voltage applied to the electrodes. The sensitivity of the gas sensing circuit is automatically varied based on the concentration of refrigerant gas present. The leak detector includes a signal generating circuit that causes a number of audible and visual indications to be generated based on the concentration of refrigerant gas sensed as well as other operating conditions.

Abstract: A gas leak detector that operates on the corona principle having a sensing tip with a pair of electrodes across which a high voltage is provided to generate a corona current through the electrodes. The sensing tip includes a first electrode having a conductive housing with a first end having a gas inlet formed therein and a second end and a flow passage formed therein. The flow passage has a first bore provided between the gas inlet and the second end of said conductive housing and a second bore having a diameter smaller than that of the first bore. The second bore is provided between the first bore and the gas inlet of the conductive housing and abuts the first bore to form an edge in the interior of the housing. The flow passage also has a third bore of a diameter smaller than that of the second bore provided between the second bore and the gas inlet. The gas leak detector also includes a second electrode provided in the interior of the conductive housing.

Abstract: A sample is loaded along with a carrier gas into a column. The column discharge is introduced into a chamber downstream of spaced electrodes which create a pulsed DC spark. The spark produces a spectral emission and a metastable carrier gas dispersion that then reacts with molecules of the sample to bring the sample to an excited state. The excess energy surrendered by the sample is characteristic of the species and can be measured by detector electrodes in the chamber.

Abstract: A method and apparatus are provided for automatically compensating for gain variations, component aging and drift characteristics of an associated circuit when trying to detect a leak. In the preferred embodiment an analog to digital converter will convert an analog signal from a sensor to a digital representation. A microprocessor will read the digital representation and compute the percentage change of the difference in values of the digital representations. Wherever the percentage change is greater than a threshold value, the microprocessor will activate an alarm to inform the user.

Abstract: A leak detector has a dual sensitivity due to two thresholds, a first established by a standard leak of the test gas representing the smallest leak to be detected, and the second as a fraction of the first one. A variable autozero level is used to compensate for background but is limited in its range to prevent masking of the leak by the autozero level. When measured gas concentration in excess of the autozero level exceeds the second threshold, the autozero value is held at a fixed value and an annuciator produces a signal as a function of the concentration so that the maximum concentration and the leak site can be found. When the leak site is found, the operator selects the first threshold for comparison with the gas concentration in excess of the held autozero value to determine whether the leak exceeds the rejection level.

Abstract: 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.

Abstract: Apparatus for determining the physical uniformity of a charged drum surface wherein current signals are induced in sensing electrodes in response to variation in drum surface charge. The sensing electrodes are on a detector assembly which is movable toward the drum for inspection of the surface and movable away from the drum after inspection when the drum is to be ejected from the apparatus. The detector assembly is movable through another degree of freedom to accommodate irregularities in drum geometry encountered during rotation thereof. The detector assembly also is provided with structure for maintaining a predetermined spacing of the sensing electrodes from the drum surface during relative movement therebetween. The drum is received, held, and rotated by co-operation between a drum retention assembly and a drum clamping mechanism.

Abstract: Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples (20) are rotated on a turntable (15) beneath selectable, co-available electrostatic chargers (30/40), one being a corona charging element (30) and the other a sample-engaging triboelectric charging element (40). They then pass under a voltage meter (25) to measure the amount of residual charge on the samples (20). After charging is discontinued, measurements are continued to record the charge decay history over time.

Abstract: An apparatus for detecting position of internal fault in a gas-insulated bus bar (1) comprises electrodes (30) each of which are provided in section of predetermined length along axial direction of the tubular-shaped housing and the electrodes (30) can detect changes of voltage of a conductor (3) in each section and thereby can detect a point of fault.

Abstract: An apparatus for continuously adjusting the corona discharge currrent of a pair of electrodes exposed to an atmosphere of gaseous impurities, particularly halogen. The device consists of a power supply to cause a corona current to flow in a pair of electrodes in series with a summing resistor. Any change in the gaseous impurities which causes a change in the corona current is sampled in the resistor, detected, delayed, amplified and fed back in proper phase to the control element of the power supply to cause the corona current to remain constant. During the finite delay time the change in corona current causes an audible alarm to sound until the corona current is restored to the new level of impurity concentration. The corrective action is continuous for any level of impurity concentration.

Abstract: A medium to be charged is conveyed past a corona charging device, so that charge emitted by the corona charging device is deposited on the medium surface. A measuring wire disposed between the medium and the corona charging device, but positioned near the medium, collects a part of the emitted charge. A first measuring circuit is used to determine a measure i.sub.d of the charge current collected by the measuring wire. A second measuring circuit determines a measure i.sub.f of that part of the emitted charge current that flows to the medium. In accordance with a predetermined relation, a value E of the surface potential is derived from these measures i.sub.f and i.sub.d.

Abstract: Disclosed is a process and apparatus for measuring, in a continuous and contact-free manner, the thickness of a layer applied to a support. The apparatus includes a measuring apparatus which comprises a corona and a first electrostatic voltmeter positioned downstream of the corona in the direction of travel of the layer being measured. The process includes the steps of passing the layer under the apparatus, charging the layer in a contact-free manner, and measuring the level of the charging voltage.

Abstract: In the known electrical mobility analyzer, a novel means for charged particle detection instead of measuring the low level current carried by the particles is provided. This detection is based on the burst corona occuring from a positive corona electrode applied with a voltage slightly lower than its onset voltage at an instant when a negatively charged particle arrives at the tip of the corona electrode. This detection detects and counts the burst corona pulses produced by the particles negatively precharged.

Abstract: A relatively simple and compact device is disclosed for monitoring ion imbalance at a preselected, or work, area. A collector is utilized that is charged due to ions contiguous thereto, with the charge at the collector being processed, preferably utilizing a charging capacitor and operational amplifier, to provide an output signal indicative of ion imbalance at the preselected area, which output signal is then utilized to produce an indication of ion imbalance at the preselected area and/or to correct the ion output of an ion generator directing ions toward the preselected area. A pair of collectors can be utilized to separately sense positive and negative ions separately generated by an ion generator with the acquired charge on each collector being separately processed, and the indication of ion imbalance can be accomplished utilizing a meter and/or alarm.

Abstract: A method of detecting and sorting pieces of insulating materials admixed in small pieces of conductive materials, which comprises detecting and amplifying the surface potentials of the conductive materials and the insulating materials by a surface potentiometer on the basis of a time differentiation method, inputting the signal to a comparator, and sensing the presence of the insulating materials. This method is utilized to detect and sort plastics admixed in pulp and papermaking materials or cereals.

Abstract: A halogen gas detector employing the negative corona principal is equipped with a corona discharge sensing tip utilizing the "electrical wind" phenomenon of field corona discharge to create a continuous flow of the gas sample being sensed through the corona, thereby ensuring that virtually every molecule of halogen gas impurity comes into contact with the corona discharge for dependable, uniform, and substantially instantaneous gas sensing operation.

Abstract: An improved apparatus for measuring the grain-size composition of powders in which a device for transforming a powder into a gaseous flow of individual particles, a charging chamber in which each particle acquires a charge which is proportional to its surface area, a precipitating capacitor in which the flow of charged particles is separated into various fractions in accordance with the charge on the particles, an electrometric device for measuring the total charge of individual fractions are provided, the electrometric device having inductive sensors of charged particles, the number of inductive sensors being equal to the number of fractions, and an amplifier to which are connected all inductive sensors of charged particles. The improvement comprises a plurality of switching devices, one switching device being provided for each sensor.

Abstract: A method and apparatus for measuring the presence of trace amounts of a halogen gas in ambient air by changes in conductivity of a negative corona in an electrical sensing gap due to the presence therein of such electro-negative gas molecules, utilizes a digital feedback loop sensitive to gap corona current to adjust the high voltage producing the corona discharge to obtain the optimum corona current for best sensitivity irrespective of the concentration of the halogen contaminant present. The presence of the halogen gas contaminant in the air is indicated by a bi-level audible alarm consisting of a periodically interrupted tone the frequency of which goes above or below a base line value to indicate small variations in impurity concentration above or below the base line concentration, and the tone interruption rate of which, at the same time, increases for large impurity concentrations.

Abstract: A surface potentiometer has a conductive shield housing provided in proximity to a body to be measured, a cage-shaped chopper rotatable within the housing, and an electrode disposed further inwardly of the chopper. The chopper is rotated to induce in the electrode a voltage corresponding to the potential of the body to be measured, thereby measuring the surface potential of the body to be measured.

Abstract: The invention provides an apparatus and method for monitoring the electrical conductivity of a web surface in which a forwardly moving web is exposed to an electrical field generated by a forwardly extending high voltage source so disposed adjacent the web as to induce a transverse redistribution of the electrical charges present on the web surface, the electrical field signal generated by the redistributed surface charges of opposite polarity to that of the source being monitored by a suitable field detector.