Asea Aktiebolag

Abb Research Ltd.

Asea Brown Boveri Ab

Anders Persson

Bo Bijlenga

Lennart Zdansky

Torgny Brogardh

Peter Lundberg

Sven-Erik Soderstrom

Christer Ovren

Morgan Adolfsson

Bernt Ling

Marja Widell

Hans Bertilson

Otto VonKrusenstierna

Jan Bergstrom

A method and a device for controlling a switching operation consisting of a turn on or a turn off operation in a voltage controlled power transistor is provided. At least one current source is arranged at the control electrode of the power transistor. The at least one current source controls the recharging of at least one of the capacitances which occurs between the control electrode of the power transistor and the main electrode of the power transistor to determine the time rate of change of at least one of the voltage and current.

Method and device in power transistor

A power supply apparatus for a drive unit in a high voltage converter circuit, the circuit has a plurality of power semiconductors connected in series. Each power semiconductor is connected to a drive unit for turning the power semiconductor on and off. The power supply apparatus consists of a capacitor and a regulator connected in parallel with the power semiconductor. The capacitor is connected to the drive unit and stores sufficient energy for power supply of the drive unit. The regulator regulates the voltage across the capacitor.

High voltage converter circuit

A method and a device for control of a switching operation consisting of a turn-on or turn-off operation in a voltage-controlled power transistor (T1), wherein at least one current source (S1, S2) is arranged at the control electrode (G) of the power transistor for controlling the recharging of at least one of the capacitances which occurs between the control electrode (G) of the power transistor and the main electrodes (C, E) of the power transistor and thus to determine the time rate of change of at least one of the quantities voltage and current.

The invention relates to a fiber optical measuring device for measuring physical quantities such as temperature and pressure, comprising a measuring transducer comprising a sensor material, an electronic unit comprising an evaluating electronic system, light sources and photo-detectors, and one or more optical fibers which connect said transducer to said electronic unit. The invention is characterised in that the sensor material has optical properties dependent on the modulating frequency of the light, such as absorption, reflection or luminescence; that the light from the electronic unit is arranged to be modulated by one or more frequencies; that at least one of these frequencies lies within the frequency range where the optical properties of the sensor material are influenced by at least one of said physical quantities; and that the modulating amplitude and/or the modulating phase position of the light emanating from the sensor material is/are arranged to be detected in the electronic unit at at least one of said modulating frequencies.

Fiber optical measuring device with a frequency sensitive transducer

In an optical measuring device for measuring physical magnitudes a sensor is actuated by the physical magnitude to be measured. An optical signal generator and processor provides light signals to the sensor and processes optical output signals transmitted from the sensor. Optical fibers conduct light to the sensor and transmit light signals therefrom to optical detectors. The sensor modulates at least a portion of the light transmitted thereto such that the modulated light output therefrom transmitted to the optic processor contains measuring components representative of the magnitude to be measured and stabilizing component signals independent of the magnitude. The optical processor separates the measuring components and the stabilizing components and generates at least one measuring signal and compensating signals for stabilizing the measuring device.

Optical measuring device using optical fibers

A visibility measuring system which comprises a radiation emitter which is capable of emitting radiation such as laser pulses in the medium in which the visibility range is to be measured, the radiation emitter being rotatable to emit the pulses in varying directions, a number of reflectors which are spaced at differing predetermined distances from the radiation emitter and laterally with respect to one another, and a radiation receiver for receiving and detecting radiation pulses reflected from each reflector; the measuring system including a device responsive to the amplitude of reflected pulses to control the direction of pulse emission from the radiation emitter to reflect from the not more than two reflectors needed to identify the current visibility range.

Automatic visibility measuring system

A cloud altitude measuring means for detecting the existence of and the distance to a cloud comprising a light emitting means, a light receiving means, a plurality of integrators activated at separate time intervals to receive the output signal from the light receiving means, a signal summation device to receive and determine the difference between the signals in the said integrators, and a signal processing circuit to receive the output signal from the signal summation device, which circuit comprises a memory circuit to store a first series of measurement value pulses from said summation device and a comparison device for comparing the first series of measurement value pulses stored in the memory with a second time delayed series of measurement value pulses to detect a cloud echo when the comparative difference between the measurement value pulses exceeds a specified value.

Cloud altitude measuring apparatus

A system for determining the oxygen activity in molten metals includes a measuring probe insertable in the melt and provided with an electrochemical cell, a thermoelement, and three contact devices. The probe is mounted at the end of a measuring lance. A preamplifier mounted on the lance is connected to the contact devices and furnishes the signals received to a preamplifier which supplies signals to a calculating unit which converts the EMF of the electrochemical cell and the EMF of the thermoelement to magnitudes representing the oxygen acitivity and the temperature, which are either recorded or observed on indicators. The measuring probe is mounted in a paper sleeve which is removable attached to the end of the lance. The electrochemical cell includes a body of solid electrolyte passing through the outer end wall of the cell and connected to one of the contact devices.

Growing community of inventors

Vaster.ang.s, Sweden

Anders Persson