Computerized Central Control for Commercial Applications

Article excerpt

Energy conservation has been a buzzword for residential/commercial irrigation this past decade. As we start the new millennium, energy conservation will be a necessity for growth in residential/commercial irrigation.

In the western United States, water regulations restrict water availability, while (in my experiences) from the Midwest to the East, the cost of water puts residential/commercial irrigation systems in a vulnerable position for existence. The residential/commercial irrigation vulnerability has prompted us industry professionals to educate our clients about the payback of irrigation as impacted by low water usage or the availability of re-used water. Both of these approaches demand control of water application for direct and flexible usage for irrigation.

Computer central-control systems for commercial properties give us the highest level of water management. These are computer systems that operate a group of satellite controllers and irrigation devices, including sensors that are controlled by central computer.

Computer central controls not only operate field devices but monitor the sensor usage. For example, the sensor will monitor pumping flow, water metering flow, electrical consumption, soil moisture, reservoir levels and weather (including wind, rain, and solar heat). Then the computer central controls can dissimulate the sensor data and operate the irrigation per site conditions, then develop a database that maintenance operations can adjust from site conditions characteristics.

Computer central-control components consist of a computer, satellite controllers, sensors and communication devices.

The communication and satellite controls can either be on-site or at central maintenance, though the central computer is usually at central maintenance. Communication devices for the controls are telephone modems, radio modems, or direct field wire modems. There are also encoder devices at the computer to interface computer with field devices.

The central computer system's uniqueness is broken down in the software to achieve maximum control. Software features for controlling schedules are the following:

* Time window -- Scheduling by time period allows the user to establish limits within which a zone will operate. The user can use this method to allow total automation of a zone in conjunction with devises such as soil moisture sensors. A time period is defined so the schedule can operate when necessary within the established window.

* Master schedules -- These allow the user to change operation of large number of schedules or zones by changing only the master schedule.

* Cycle-and-soak -- This allows the user to set a maximum station cycle time a station can operate at any one time between these cycles. This is very useful for areas where irrigation application rates exceed the soil's infiltration rate. …