Electrical Components & Controller Programming Flashcards

What is the benefit of 'predictive watering' or 'weather-based scheduling' in a smart controller compared to a fixed timer schedule?

Answer: It automatically adjusts irrigation run times based on real-time and forecasted weather data, applying only the amount of water plants have lost to evapotranspiration

Weather-based scheduling (using ET data and weather forecasts) automatically adjusts irrigation daily based on actual conditions. On hot, dry, windy days run times increase; on cool, humid, or cloudy days they decrease. This typically saves 20-40% water compared to fixed schedules.

A controller has a 'pump start relay' output terminal. What is the purpose of this feature?

Answer: To send a low-voltage signal to a pump start relay, which then activates the pump's high-voltage power supply when any irrigation zone is running

The pump start relay terminal provides a 24 VAC signal to a pump start relay whenever any zone is active. The relay, in turn, switches the pump's high-voltage power (120/240 VAC). This allows the low-voltage controller to safely control a high-voltage pump motor.

An irrigation controller is found to be running zones that should be off — multiple zones activate simultaneously even though the schedule shows only one zone at a time. The most likely cause is:

Answer: A short circuit between zone wires in the field (wires touching or insulation damaged)

When multiple zones activate simultaneously or zones run when they shouldn't, a short circuit between zone wires in the field is the most common cause. Damaged insulation allows current from an active zone wire to leak to adjacent zone wires, energizing those solenoids.

What is the advantage of using pressure-compensating sprinkler heads in an irrigation zone with significant elevation changes?

Answer: They maintain a consistent flow rate and spray pattern regardless of pressure variations caused by elevation differences across the zone

Pressure-compensating heads use internal regulators to maintain consistent operating pressure (and thus consistent flow rate and spray radius) despite variations in supply pressure caused by elevation changes. Heads at the bottom of a hill and top of a hill perform identically.

When connecting a weather station to a smart irrigation controller, the station should be mounted in a location that:

Answer: Receives unobstructed sun, wind, and rain exposure representative of the landscape conditions

An on-site weather station must be exposed to actual weather conditions — direct sunlight, wind, and precipitation — to accurately measure the parameters used for ET calculations and weather-based scheduling. It should represent typical conditions of the irrigated landscape.

A controller's 'manual single station' mode is used to:

Answer: Run one specific zone on demand for testing, maintenance, or immediate watering without affecting the automatic schedule

Manual single station mode allows the technician to activate one specific zone on demand — useful for testing repairs, checking head coverage, running an audit, or providing emergency watering. The automatic schedule is not changed and resumes normally after the manual run.