COMPENSATION OF SIMPLE FIBER OPTIC FARADAY EFFECT SENSORS

• US 20100295692A1
• Filed: 10/30/2009
• Published: 11/25/2010
• Est. Priority Date: 11/18/2004
• Status: Active Grant

• Current Assignee: Landis+Gyr Oy (Landis+Gyr Group AG)
• Original Assignee: Powersense A/S
• Inventors: Bjørn, Lars N.
• Granted Patent: US 8,949,054 B2
• Time in Patent Office: Days
• US Class Current: 340/650
• CPC Class Codes: G01R 1/00 Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 constructional details particular to electromechanical arrangements for measuring the electric consumption G01R11/02
• CPC Class Codes: G01R 15/246 based on the Faraday, i.e. linear magneto-optic, effect
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 33/0322 using the Faraday or Voigt effect
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04W 4/14 Short messaging services, e.g. short message services [SMS] or unstructured supplementary service data [USSD]

Abstract

A monitoring system for detecting earth faults in an electrical power supply grid providing a power signal includes a plurality of monitoring devices, each of the monitoring devices including a detector for detecting the level of harmonics in the power signal, wherein the level of harmonics is detected in a specific frequency range. Each of the monitoring devices further includes a memory for storing a harmonics reference value, a processor for comparing the detected level of harmonics with the reference level, and a communication device for transmitting an alarm if the detected level of harmonics is above the reference level for a specific period of time. Each of the detectors includes an optical sensor for detecting the harmonics by use of the Faraday effect.

Claims

1-14. -14. (canceled)

15. A method of communicating between a master unit and a plurality of monitoring units monitoring an electrical power supply grid, said master unit comprising a communication unit connected to a wired or wireless network for communicating with said plurality of monitoring units, each of said monitoring units comprising a transmitter and receiver having a wired or wireless connection to said network for transmitting and receiving data messages to and from said master unit, each of said monitoring units comprising a memory unit for storing one message,

said method comprising:

transmitting a message from said master unit to at least one of said monitoring units,

receiving said message by at least one of said monitoring units, and, if said memory unit is empty, storing said received message in said monitoring unit, and if a previously received message is stored in said memory unit, discarding said received message from said memory unit.

16. The method according to claim 15, wherein said method further comprises:

transmitting a response by said monitoring unit to a message stored in said memory unit.

17. The method according to claim 15, wherein said master unit monitors if a response to said transmitted message is received with in a specific period of time.

18. The method according to claim 17, wherein, if no response is received within said specific period of time, said master unit retransmits said message.

19. The method according to claim 17, wherein said response sent by said monitoring unit is selected from the group consisting of at least one of voltage levels, phase information, fault status, fault settings, and fault indications.

20. The method according to claim 15, wherein said network is selected from the group consisting of at least one of a GSM network, a 3G network, WLAN network, and a PSTN network.

21. The method according to claim 15, wherein said message is in a format selected from the group consisting of at least one of a short-message-service format, a text format, and a binary format.

22. A system for monitoring and/or determining conditions at a first side of a transformer by measuring currents at a second side of said transformer, voltages at said first side being higher than voltages at said second side, said system comprising:

an optical unit including an optical transmitter and an optical receiver connected by an optical conduit comprising a sensor for sensing electrical fields, said sensor being positioned at a cable at said second side of said transformer;

a memory unit for storing transformer related information; and

a processor unit configured for determining currents in said cable based on optical power transmission from said optical transmitter through said optical guide and received at said optical receiver.

23. The system according to claim 22, wherein said processor is further configured for calculating voltage conditions on said first side of said transformer based on said optical power transmission and said transformer related information.

24. The system according to claim 22, wherein said system further comprises an output unit configured for outputting data representing at least one of said current conditions and said voltage conditions at said first side of said transformer.