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Download Irrigation system troubleshooting - Metropolitan Water District of
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California Friendly Landscape Training ® Irrigation System Troubleshooting The Metropolitan Water District of Southern California and the Family of Southern California Water Agencies California Friendly® Landscape Training Workshop 1: Irrigation Principles & System Adjustment and Repair Workshop 2: Irrigation System Troubleshooting Workshop 3: Controller Programming Workshop 4: Irrigation Scheduling Today’s Workshop Irrigation System Troubleshooting • Electrical Concepts • Field Skills • Electrical System • Mechanical Operation • Troubleshooting Steps Water Efficient Devices • Rotating Nozzles • Smart Sprinkler Controllers • Synthetic Turf Goal of Today’s Workshop To open and close the valve with the irrigation controller! Controller Valves Electrical Concepts • Current • Voltage • Resistance All these are related, but they’re not the same thing! Current • Current is the movement or flow of electrons • Amps • Current activates the valve solenoid Wire Current: rate of speed of electrons Voltage • Voltage is the force that pushes electrons through the wire • Volts (VAC or VDC) Wire Voltage: Force that pushes electrons Types of Voltage • Direct Current (VDC) • Flow is in one direction from batteries • Alternating Current (VAC) • Flow alternates direction – typical electrical systems Resistance • Resistance to flow of electrons • Affected by wire size and length • Measured in Ohms (symbol Ω) Wire Smaller Wire Higher Resistance lowers amount of Current to Solenoid! For Troubleshooting... • Need to measure Voltage (Volts) to check the Controller • Need to measure Resistance (Ohms Ω) to check the wiring, solenoid, and connections Controller Valves Typical Electrical System Irrigation Controller Common Wire 24-28 VAC 110 VAC 24-28 VAC With Step-Down Transformer Valve Solenoid(s) Controller • 110 VAC supply voltage – very dangerous! • Flows through step-down transformer • 24 VAC Volts output to control valves • Controller switches open and close valve circuits Typical Voltage 110 VAC • Supply to Controller 24 VAC • From Controller to Valves Measurements • Volt-Ohm Meter • Multi-Meter • “Check Mate” Voltage Measurements • Meter Setting • Probe Placement • Safety Safety 120 Volts – very dangerous! • Experienced personnel only 24 Volts – not dangerous • But be careful – work with caution Measuring Voltage - VAC Tip: disconnect the common wire from the terminal Input and Output Voltage Valves Output 24-28 VAC Input 110 VAC Controller Output 24-28 VAC Voltage Output Problems If less than 24 Volts: • The controller station switch may be faulty If more than 28 Volts: • The transformer may be faulty – may need to replaced If voltage output is OK, check field circuitry next... Control Circuit Two Wires • Control Wire • Switched, Open or Closed • Common Wire Common Wire Control Wires Measure Resistance to Check Circuits • Resistance in Wire (Conductors) • Resistance to electrical movement • Wire size and length • Units – OHM () Resistance Readings Wire - 1,000 feet of 14 gauge wire • 3 Ohms (approx.) Solenoids – different manufacturers • 20 to 60 Ohms for most solenoids • Some have very high readings (Griswold) Resistance of Solenoid Wiring Problems Wiring problems that resist the amount of current to the solenoid • Broken Wires • Inside the Solenoid • Control Wire • Common Wire • Bad Connections • Solenoids • Junction Boxes • At the Controller • Damaged Wires • During Installation • Other construction done after installation of wires (fences, trenches, etc.) • Tree Roots • Animals Steps and Safety • Power OFF! • Damage the multi-meter • Tip: disconnect common • Set meter scale high • One probe at common wire • Other probe at control wire • Begin test Resistance Reading Circuit Condition 1. Closed – Complete/Good Circuit 2. Open Circuit – Fault 3. Partial Open Circuit – Fault 4. Short Circuit – Fault 1. Complete (Closed) Circuit • Functioning properly • Proper flow of electricity between Controller and Control Valves • There are no wire breaks, shorts, or bad connections Typical Response Complete Circuit Closed/Complete Circuit: • Resistance Reading: 20-60 Ohms – Normal 2. Open Circuit Fault • There’s a break in the circuit • Break in the wiring • Break inside the solenoid • A connection came apart Typical Response Open Circuit Open Circuit Fault: • Maximum Resistance, infinite Ohms • 1 on left side of display (digital meters) • This circuit will not operate 3. Partial Connection • Circuit wires make partial connection at: • Controller • Control Valve • No waterproof connectors • Nicked or damaged wires (not completely broken) Typical Response Partial Connection Partial Connections Fault: • Resistance: higher than normal Ohms • Erratic system performance 4. Short Circuit Fault • Common wire and Station (Control) wire make contact • Solenoid interior coil wires make contact Typical Response Short Circuit Short Circuit Fault: • Fuse will burn or breaker will trip • Resistance Reading: 0 to 10 Ohms • This circuit may come on with other valves Summary of Circuit Conditions Circuit Condition 1. Closed Circuit 2. Open Circuit 3. Partial Connection 4. Short Circuit Resistance - Ohms 20-60 Ω Maximum Ω Higher than normal 0-10 Ω Waterproof Connectors Black Box Exercise Notes: • Simulation of circuit conditions • Closed Circuits • Open Circuits • Partial Connections • Short Circuits Questions? Electrical Troubleshooting Mechanical Troubleshooting • Water Supply • Valve Operation Valve – Closed Valve – Opening Valve – Open Flow Control Outlet Port Bleeder Screw Valve Spring Diaphragm Stopper Valve Body Inlet Port Valve Seat Common Valve Problems • Cracked diaphragm • Broken spring • Plugged inlet port • Calcium deposits inside solenoid • Rocks or debris on stopper seat Valve will not Open • Insufficient Voltage • Hole on the diaphragm (Reverse Flow Valves) • Flow stem is closed • Plunger is stuck or missing • Outlet port is plugged • Bad Solenoid Valve will not Close • Hole on the diaphragm (forward flow valve) • Debris on the valve seat • Flow stem turned up too high • Inlet port gets plugged during operation Valve Assembly • Class Exercises • Disassemble Valve • Reassemble Valve Wiring from Top of Valve Removed Screwing off Top of the Valve Spring Removed from Valve Diaphragm Empty Valve Housing Reassembled Valve Look for the obvious first • Is the water turned on? • Is the controller plugged in? • Is the timer programmed correctly? • Is there an isolation valve? Questions? California Friendly® Landscape Training Your hosting water agency would like to thank you for being water conscious and attending this Workshop
