Rosemount Tank Radar Ab

Håkan Nyberg

Leif Nilsson

Håkan Delin

Mikael Eriksson

Håkan Fredriksson

Jan Westerling

Leif Nilson

A guided wave radar level gauge comprising a housing providing explosion proof protection and having an intrinsically safe output, a transmission line probe connected to the IS output. The housing encloses radar level gauge circuitry which is incompatible with intrinsic safety requirements, a microwave unit connected to the IS output, an electrical barrier connected between the RLG circuitry and the microwave unit, the electrical barrier having a barrier ground potential which is independent from the grounded housing wall, and a set of blocking capacitors connected between the microwave unit and the IS output.

Guided wave radar level gauge with explosion proof housing and floating barrier

A pulsed radar level gauge comprising a pulse generator configured to generate a transmit signal (S) in the form of a pulse train, a propagation device connected to direct the transmit signal (S) into a tank and return a microwave return signal (S), a receiver, sampling circuitry configured to provide a time expanded tank signal, and processing circuitry for determining said filling level based on the time expanded tank signal. The gauge further comprises impedance increasing circuitry arranged to ensure that an input impedance of the receiver is at least 2 k&#x3a9; and a delay line arranged between said receiver and said propagation device, the delay line configured to introduce a delay greater than said pulse duration, such that said time expanded signal includes a transmitted pulse.

Pulsed radar level gauge with feedback of transmit pulse

A guided wave radar level gauge comprising an explosion proof housing with an intrinsically safe (IS) output, a resistor having a first terminal connected to the IS output and a second terminal connected to the housing ground potential, and a transmission line probe connected to the IS output. The housing encloses radar level gauge (RLG) circuitry and a microwave unit having a floating ground potential, and a set of blocking capacitors connected between the microwave unit and the IS output. The microwave unit includes a differential receiver, having a first terminal connected to the IS output via the set of blocking capacitors, and a second terminal connected to the housing ground potential via the set of blocking capacitors, a voltage between the first and second terminals forming an input signal to the differential receiver.

Guided wave radar level gauge having an explosion proof housing with an intrinsically safe output

A radar level gauge system comprising a first transceiver; a second transceiver; an antenna arranged to radiate a first transmit signal generated by the first transceiver and a second transmit signal generated by the second transceiver, and to receive a first reflection signal and a second reflection signal; a tubular waveguide to guide the transmit signals towards the interface, and to guide the reflection signals back towards the antenna; a plurality of signal interacting structures arranged at different levels along a the tubular waveguide, to selectively interact with the second transmit signal to contribute to the second reflection signal; and processing circuitry to determine a level of the interface between liquid phase product and vapor phase product based on a relation between the first transmit signal and the first reflection signal, and a density distribution based on a relation between the second transmit signal and the second reflection signal.

System and method for determining level and density distribution

The present invention relates to a field device adapted to determine a process parameter value related to a tank, the field device comprising a terminal block with: a first interface configured to connect to two wires of a loop; a first electrical conductor and a second electrical conductor for connecting the first interface with field device electronics, the second electrical conductor having a voltage drop generating element; a first power supply conductor connected to said second electrical conductor upstream of the voltage drop generating element and a second power supply conductor connected to said second electrical conductor downstream of the voltage drop generating element; and a second, auxiliary interface adapted for wired connection to an external device and configured at least for communication with said external device, wherein the second auxiliary interface comprises a communications connector which is galvanically isolated from the field device electronics.

Field device with second auxiliary interface

The present invention relates to a method of controlling a pulsed radar level gauge system, comprising the steps of: acquiring a signal indicative of a present operating temperature; determining an initial frequency control parameter for control of at least one of transmission signal generating circuitry and reference signal generating circuitry based on the present operating temperature and a plurality of data sets each comprising data indicative of a previous operating temperature and a previously determined frequency control parameter for the previous operating temperature; and controlling, starting from the initial frequency control parameter, at least one of the transmission signal generating circuitry and the reference signal generating circuitry to achieve the known frequency difference between the first pulse repetition frequency and the second pulse repetition frequency at the present operating temperature.

Pulsed level gauge system with temperature-based control of pulse repetition frequency

The present invention relates to a field device for determining a process variable and providing a measurement signal indicative of the process variable to a remote location via a two-wire current loop. The field device comprises a measurement device for determining the process variable; a current control device electrically connected in series with the measurement device and controllable by the measurement device to provide the measurement signal to the two-wire current loop; and voltage regulation circuitry electrically connected in series with the current control device and the measurement device for controlling a voltage across the current control device towards a desired voltage by varying a voltage across the voltage regulation circuitry.

Loop-powered field device with voltage regulator and current source in series

A method for powering a radar level gauge, comprising an initial frequency stabilization procedure, ensuring a stable separation frequency between a first and a second clock frequencies, during which frequency stabilization procedure said radar level gauge is not powered to provide a level output, and a subsequent measurement cycle, performed only when a stable separation frequency has been established, during which said radar level gauge is powered to provide a level output. The present invention allows a radar level gauge system to save power by not providing power to and operating the radar level gauge circuit during such times when the frequency separation would not enable the radar level gauge to provide proper level measurements.

Pulsed radar level gauging with efficient start-up

The present invention relates to a pulsed level gauge system comprising frequency control circuitry. If an acquired signal indicates that the time between the previous filling level determination and the present filling level determination is shorter than a predefined time, the frequency control circuitry controls at least one of a transmit signal generating circuitry and a reference signal generating circuitry comprised in the pulsed level gauge system using previous frequency control settings stored in memory. If the acquired signal indicates that the time between the previous filling level determination and the present filling level determination is longer than the predefined time, the frequency control circuitry iteratively regulates at least one of the transmit signal generating circuitry and the reference signal generating circuitry towards achieving a desired pulse repetition frequency difference between the pulse repetition frequency of the transmit signal and the pulse repetition frequency of the reference signal.

Pulsed level gauge system and method

A method of determining a filling level of a product contained in a tank using a level gauge system, comprising the steps of: transmitting a first signal towards a surface of the product; receiving a first echo signal; determining a present echo characteristic value based on the first echo signal; and comparing the present echo characteristic value and a stored echo characteristic value. If a difference between the present echo characteristic value and the stored echo characteristic value is greater than a predefined value, the method further comprises transmitting at least a second transmit signal towards the surface; receiving at least a second echo signal; and determining the filling level based on the at least second electromagnetic echo signal.

Intermittent filling level determination with dynamically determined number of measurements

The present invention relates to a method comprising providing an activation signal from a wireless communication unit to a measurement unit to switch the measurement unit from its inactive state to its active state; providing a measurement request signal to the measurement unit to request measurement of a filling level of a product in a tank; and thereafter switching the wireless communication unit from its active state to its inactive state. The measurement unit measures the filling level and provides a measurement ready signal to the wireless communication unit; the wireless communication unit is switched from its inactive state to its active state in response to the measurement ready signal received from the measurement unit; the wireless communication unit retrieves the value indicative of the filling level from the measurement unit; and wirelessly transmits the value indicative of the filling level to the remote device.

Battery-powered level gauge system adapted for wireless communication

The method comprises the steps of generating a transmission signal; propagating the transmission signal towards the product; receiving a reflected signal; providing a reference signal exhibiting a time-varying phase difference in relation to the transmission signal; forming a measurement signal; and determining the filling level based on the measurement signal. The method further comprises the steps of: determining a reduced time period comprising a time when the time-varying phase difference corresponds to an anticipated filling level, the reduced time period being shorter than the measurement sweep time period; controlling the level gauge system to change from a low-power state to a high-power state at a start of the reduced time period; and controlling the level gauge system to change back from the high-power state to the low-power state at an end of the reduced time period.

Pulsed level gauge system with adaptive transceiver control

A radar level gauge system comprising first pulse generating circuitry for generating a transmission signal, second pulse generating circuitry for generating a reference signal; and frequency control circuitry for controlling the second pulse generating circuitry to achieve a predetermined frequency difference between the transmission signal and the reference signal. The radar level gauge system further comprises first frequency selection circuitry configured to provide a higher order harmonic frequency component of the transmission signal to the frequency control circuitry; and second frequency selection circuitry configured to provide a higher order harmonic frequency component of the reference signal to the frequency control circuitry. The frequency control circuitry is configured to control the second pulse generating circuitry based on the higher order harmonic frequency component of the transmission signal and the higher order harmonic frequency component of the reference signal. Hereby, improved regulation of the reference signal can be achieved substantially without any increase in power consumption of the radar level gauge system.

Pulsed radar level gauge system with higher order harmonic regulation

The invention sets forth a method of determining a filling level of a product contained in a tank using a radar level gauge system. The steps include generating a transmission signal using first pulse generating circuitry outputting a first signal having a first oscillation frequency having a first pulse repetition frequency. The invention uses a second pulse generating circuitry having a resonator element having an input and an output, a reference signal in the form of a second pulse train having a second pulse repetition frequency which differs from the first pulse repetition frequency by a predetermined frequency difference. The invention forms a measurement signal including a sequence of values representing a time correlation between a pulse of the reference signal and the reflected signal, and determines the filling level based on the measurement signal. The step of generating the reference signal includes providing the first signal to the input of the resonator element in the second pulse generating circuitry, monitoring an output signal from the resonator element, the output signal substantially corresponding to the first signal being delayed by a time delay, controlling at least one parameter of the second pulse generating circuitry to a parameter value resulting in the time delay corresponding to the predetermined frequency difference, and providing the output signal from the resonator element to the input of the resonator element while maintaining the parameter value of the at least one parameter, thereby generating the reference signal.

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Linköping, Sweden

Håkan Nyberg