Radar level gauge system and method for controlling the radar level gauge system

1. A radar level gauge system comprising:

a communication module configured to be connected to an external communication device;

a measurement module configured to generate, transmit and receive a measurement signal;

a control connection configured to connect the communication module to the measurement module, the control connection being configured to be in a high-impedance mode at least during a measurement by the measurement module;

a power supply configured to provide power to the measurement module;

an energy storage coupled to the power supply;

a measurement connection connecting the communication module to the energy storage, wherein the energy storage is arranged to be charged by the measurement connection and configured to provide power to the power supply for performing a measurement by the measurement module; and

a switch arranged between the communication module and the energy storage, the switch being controllable to break the measurement connection between the communication module and the energy storage during a measurement by the measurement module.

2. The system according to claim 1 , wherein the measurement connection is a connection having an impedance which is adapted for providing power from the communication module to the energy storage.

3. The system according to claim 1 , wherein the control connection is configured to be controllable between a low-impedance mode and a high-impedance mode.

4. The system according to claim 1 , wherein the high-impedance mode of the control connection is adapted to have an impedance which is sufficiently high for preventing conducted disturbances from propagating via the control connection to the measurement module.

5. The system according to claim 3 , wherein an impedance of the control connection in the high-impedance mode is at least 10 times higher than an impedance of the control connection in the low-impedance mode.

6. The system according to claim 3 , wherein the communication module is configured to control the control connection to operate in a high-impedance mode or in a low-impedance mode.

7. The system according to claim 1 , wherein the control connection is an optical connection.

8. The system according to claim 1 , wherein the switch is further configured to be controlled by the measurement module to disconnect the communication module from the power supply during a measurement by the measurement module.

9. The system according to claim 1 , wherein the switch is a semiconductor switch.

10. The system according to claim 1 , wherein the switch is an electromechanical relay.

11. The system according to claim 1 , further comprising a second switch arranged to break the control connection between the communication module and the measurement module.

12. The system according to claim 1 , wherein the measurement module is configured to be set in a low-power mode during charging of the energy storage.

13. The system according to claim 1 , wherein the communication module is configured to be connected to a 4-20 mA current loop interface.

14. Method for controlling a radar level gauge system comprising:

a communication module configured to be connected to an external communication device;

a measurement module configured to generate, transmit and receive a measurement signal;

a control connection configured to connect the communication module to the measurement module, the control connection being configured to be in a high-impedance mode at least during a measurement by the measurement module;

a power supply configured to provide power to the measurement module;

an energy storage coupled to the power supply;

a measurement connection connecting the communication module to the energy storage, wherein the energy storage is arranged and configured to be charged by the measurement connection and to provide power to the power supply for performing a measurement by the measurement module; and

a switch arranged between the communication module and the energy storage;

wherein the method comprises:

receiving, in the measurement module, a command to perform a measurement;

controlling the switch to be in an open mode to break the measurement connection between the communication module and the energy storage;

performing a measurement by the measurement module; and

controlling the switch to be in a closed mode to reconnect the measurement connection between the communication module and the energy storage.

15. The method according to claim 14 , wherein the switch is controlled by the measurement module.

16. The method according to claim 14 , further comprising controlling the control connection to be in a low-impedance mode when the switch is in the closed mode and to be in a high-impedance mode when the switch is in the open mode.

17. The method according to claim 14 , further comprising, by the measurement module, monitoring the status of the energy storage and controlling the switch based on a state-of-charge of the energy storage.

18. The method according to claim 14 , further comprising controlling the switch based on an estimated time required for fully charging the energy storage.

19. The method according to claim 14 , further comprising controlling the measurement module to operate in a low-power mode during charging of the energy storage.