EP-3903571-B1 - A TWO-WIRE CONTROLLING AND MONITORING SYSTEM FOR IN PARTICULAR IRRIGATION OF LOCALIZED AREAS OF SOIL

Inventors

• CHRISTIANSEN, Tom Nøhr

Dates

Publication Date

20260513

Application Date

20130531

Claims (2)

1. A method for controlling and monitoring in particular irrigation of localized areas of soil and comprising the following steps of: providing a water pipeline (16) providing water to said localized areas of soil, providing a first plurality of controllable irrigation valves (42), each positioned at a specific area of said localized areas of soil, each connected to said water pipeline (16) for providing watering or non-watering of said specific area of said localized areas of soil and each having a pair of valve control inputs, providing a second plurality of localized irrigation control units (18, 202,204, 234, 236, 238, 240), each comprising a line decoder (44, 216, 224) having a pair of valve control outputs (50) connected to said pair of valve control inputs of a specific controllable irrigation valve of said first plurality of controllable irrigation valves (42) for providing valve control signals to said first plurality of controllable irrigation valves (42), said line decoder (44, 216, 224) further each having a pair of control and power supply inputs for communicating with a controller and power supply (30, 202) over a two-wire cable (28, 206), said specific controllable irrigation valve of said first plurality of controllable irrigation valves (42) comprising a solenoid connected to said valve control inputs, a core operable between a first position and a second position, and a piston connected to said core, defining in said line decoder (44, 216, 224) an inrush DC voltage level signal (102) for forcing said core into said second position, defining in said line decoder (44, 216, 224) a hold DC voltage level signal (104) for retaining said core in said second position, determining by means of said line decoder (44, 216, 224), said first position or said second position of said core, measuring a self inductance value and a resistance value of said solenoid, and characterized by transmitting by means of said line decoder (44, 216, 224) said self inductance value and said resistance value to said controller and power supply (30, 202) via said two-wire cable (28, 206) and monitoring said self inductance value and said resistance value and signals in said controller and power supply (30, 202) in case any of said self inductance value and said resistance value is outside a predetermined range, and - if said resistance and said self induction have decreased: said controller determining and reporting that said solenoid has degenerated, - if said resistance has increased, while said self induction is substantially unchanged: said controller determining and reporting a likely connection fault between said localized irrigation control unit and said solenoid.
2. A two-wire controlling and monitoring system for in particular irrigation of localized areas of soil and comprising: a controller and power supply (30,202), a water pipeline (16) providing water to said localized areas of soil, a first plurality of controllable irrigation valves (42), each positioned at a specific area of said localized areas of soil, each connected to said water pipeline (16) for providing watering of non-watering of said specific area of said localized areas of soil and each having a pair of valve control inputs, a second plurality of localized irrigation control units (18, 202, 204, 234, 236, 238, 240), each comprising a line decoder (44, 216, 224) having a pair of valve control outputs connected to said pair of valve control inputs of a specific controllable irrigation valve of said first plurality of controllable irrigation valves (42) for providing valve control signals to said first plurality of controllable irrigation valves (42), said line decoder (44, 216, 224) further each having a pair of control and power supply inputs for communicating with the controller and power supply (30, 202) over a two-wire cable (28, 206), said specific controllable irrigation valve of said first plurality of controllable irrigation valves (42) comprising a solenoid connected to said valve control inputs, a core operable between a first position and a second position, and a piston connected to said core, said line decoder (44, 216, 224) defining an inrush DC voltage level signal (102) for forcing said core into said second position, said line decoder (44, 216, 224) defining a hold DC voltage level signal (104) for retaining said core in said second position, said line decoder (44, 216, 224) determining said first position or said second position of said core, measuring a self inductance value and a resistance value of said solenoid, and characterized by said line decoder (44, 216, 224) transmitting said self inductance value and said resistance value to said controller and power supply (30, 202) via said two-wire cable (28, 206) and monitors said self inductance value and said resistance value and signals said controller and power supply (30, 202) in case any of said self inductance value and said resistance value is outside a predetermined range, and - If said resistance and said self induction have decreased: said controller is adapted to determining and reporting that said solenoid has degenerated, - If said resistance has increased, while said self induction is substantially unchanged: said controller is adapted to determining and reporting a likely connection fault between said localized irrigation control unit and said solenoid.

Description

The present invention relates to a 2-wire controlling and monitoring system for in particular irrigation of localized areas of soil and a method of controlling and monitoring in particular irrigation of localized areas of soil. Description of the related art: The most commonly known two-wire irrigation control systems, such as control systems disclosed in US patents US 4,007,458 and US 4,176,395 provide control of a number of remotely located irrigation or sprinkler valves from a central location by means of control signals encoded on to a single pair of power transmission lines linking a central encoder and a number of remote decoders. The two-wire irrigation control system according to US 4,007,458 encodes and transmits an address of a specific remotely located irrigation valve and on/off signals onto an alternating current signal (AC) by clipping half portions of the signal to represent zero values. Similarly, the two-wire interactive irrigation control system according to US 4,176,395 transmits data by selectively clipping the original power frequency signal during eight consecutive cycles, suppressing the power frequency signal during the following full cycle, during which time a feedback signal may be transmitted from sensors located at specific areas, then transmitting eight undistorted power frequency cycles, and suppressing the power frequency signal for one following cycle, during which time a feedback signal relating to a portable operator may be transmitted. Both two-wire irrigation control systems according to US 4,007,458 and US 4,176,395 communicate to remotely located irrigation valves or decoders by clipping of the power signals consequently while performing a transmission on the power line power to the remotely located irrigation valves or decoders is significantly reduced. Furthermore, the two-wire irrigation control systems according to US 4,007,458 and US 4,176,395 utilizes sinusoidal signals for transmitting powerto remotely located irrigation valves or decoders. Sinusoidal signals being AC signals generally need to be converted into DC in order to drive microprocessor electronic circuitry adding total costs of the two-wire irrigation systems for the electronics incorporated in the remotely located irrigation valves or decoders. Further similar systems are known from e.g. the applicant's own prior US patent applications and patents US 6,766,221, US 6,993,416, US 7,421,317, US 7,146,255, US 7,206,669, US 5,839,658, US 60/779,857 and US 12/281,968. US 2009/222140 describes a control and monitoring system for irrigation similar to the present invention, but it does not show that inductance and resistance values are sent back to a central controller which monitors these values and determines fault modes. Summary of the invention The invention relates to a method of controlling and monitoring an irrigation system as specified in claim 1. It also relates to the system itself as specified in claim 2. Many 2-wire controlling and monitoring systems found in the prior art do not make full use of the power bandwidth. The power bandwidth is understood to mean the ability of the 2-wire cable to deliver power from the controller/power supply to the localized irrigation control units. The theoretical maximum power bandwidth is the controller/power supply x the controller/power supply divided by 2 x Rcable. The theoretical power bandwidth may thus be increased by using thicker cables. Further, a higher effective voltage may be used. It should be noted that systems operating with a sinusoidal voltage will per se have a lower power bandwidth, which typically is about 50% of the power bandwidth of an equivalent DC system. Further, the use of power electronics may reduce the power bandwidth even further since some power electronic circuits only draw power near the peaks of the sinusoidal voltage. According to the present invention, a direct current/voltage (DC) is used, which allows a maximum power bandwidth, i.e. maximum power delivered from the controller/power supply to the localized irrigation control units. Pure DC is however not feasible due to significant risk of harmful corrosion on the 2-wire cable in connection with leakage currents between the cable and the surrounding thereof. Leakage currents may occur due to small voids and damages of the cable insulation. To avoid the corrosion, an alternating DC is used. In this way, the average voltage on each of the 2-wire cables are balanced such that the average voltage is slightly below 0 volts, such that the harmful corrosion is minimized. A leakage current from the cable to earth is very harmful since the copper in the cable is dissolved (Cu to Cu++). It is an object of the present invention to allow a two-way communication between the controller/power supply and the localized irrigation control units, in which the power bandwidth is as close to 100% as possible. The 2-wire cable may also be used for transmitting data packages between the controller