By figuring out how to utilize this year, it’s likely to troubleshoot controls, solenoids, field wiring, and also to confirm AC and DC voltage levels.
Most irrigation solenoids work on AC voltage.
The meter must be attached properly to stop meter harm, the RED guide is (+), and also the BLACK guide is (-).
This is quite much like friction reduction by means of a sheet of PVC pipe.
Additional Conditions Used in Assessing Resistance
Resistance is easily the most valuable function for monitoring irrigation methods. It’s best to compare immunity dimensions to this a brand new solenoid. But in case a solenoid of the identical brand steps 24 ohms when fresh, it might be a sign that the is deteriorating and must be replaced.
Brief – if the resistance measured is 20 ohms for one solenoid. In case the quantity of current exceeds the rating of this device, it is going to open, therefore quitting the 24 volts into the valves.
Think about this as with a stone lodged in the mainline of a sprinkler system. The immunity may rise to the point that the solenoid doesn’t find enough voltage to function.
HINT… To keep in mind the distinction between an open and a brief. An open drawbridge prevents the stream of traffic.
NOTE… .When two valves are worked collectively on one channel, the entire resistance will be significantly less than the immunity of their lowest solenoid. Case in point: when a 52 solenoid along with a 24 solenoid are united on precisely the exact same channel, the entire resistance is roughly 17, significantly less than the immunity of their cheapest solenoid (24.)
Employing The Multimeter
These instructions are written particularly for the Radio Shack catalog No. 22-179 Digital Multimeter.
AC volts – twist the dial to the AC squat position, AC will reveal at the lower left corner of the screen. Twist the meter probes into the circuit which you want to measure. NOTE…When that the mV is busy to the right of this screen, split the reading by 1000. Example, the screen shows 061 mV, the true measurement is 0.061 volts.
DC volts – twist the dial to the DC squat position. NOTE..When that the mV is busy into the right of this screen, the scanning has to be divided by 1000. Example, the screen shows 061 mV, the true measurement is 0.061 volts.
Resistance – To avoid meter harm, it’s extremely essential that the circuit electricity is turned off when measuring immunity. This indicates infinite immunity, an open circuit. The screen indicates the immunity.
NOTE. After the M is busy into the right of this screen, the reading must be multiplied by 1,000,000. Example, the screen shows 41.2 K, the true measurement is 41,200 ohms.
NOTE. .When measuring immunity from the control, you’re measuring the resistance of the cables resulting in the solenoid via the cable connector, the solenoid, the next cable connector, along with the cable resulting in the control. A resistance to these control cables doesn’t add considerably to the entire resistance. UFUL 14 is roughly 2.5 ohms per 1,000 ft, 16 gauge UFUL cable is roughly 4.0 ohms per 1,000 ft, and 18 gauge UFUL multi-conductor cable is roughly 6.5 ohms per 1,000 feet.
The Way to Interpret Display Cases
Multiply the reading from 0.001 if the MV is busy.
Multiply the reading from 1,000 if the K is busy.
Understanding how to run a meter may save substantial time when studying the wiring on work website. It’s possible to inspect the solenoid and area wiring state from the control. The Process is as follows:
1. Disconnect the frequent cable(s) in the terminal strip on the control.
3. Connect among the meter contributes to the frequent cable and not the control common terminal.
4. Twist the next meter direct to every one of the channel terminals, and document the resistance readings. Assess your readings into the acceptable assortment of 20 – 60 ohms.
5. NOTE. .This test just inspects the state of the wiring, the channel might not function properly due to control and/or valve issues.
6. If the resistance range is 20 ohms (a brief), proceed into the valve and detach the solenoid in the field cables. If the dimension is still reduced, then the solenoid has to be substituted. If the solenoid immunity is okay, then the brief is in the area wiring itself (just two solenoids linked to the channel may also generate a minimal reading). Wire tracing equipment ought to be employed to find the issue.
7. If the immunity is over 60 ohms (an open), as in step 7, then test the solenoid with no area wires connected. Replace the solenoid if its immunity is over 60 ohms. If the solenoid is great, cut the cable connectors and join the channel and common cables together in the valve location. In the control, re-test the immunity without the solenoid from the circuit. The immunity should now read quite low, maybe 5 ohms or under since the immunity of the area wires has been quantified. If the immunity is so low, then the issue was a faulty cable connector. Install fresh waterproof wire connectors onto the present solenoid and examine the immunity again in the control.
If the resistance remains high if the common and channel wires are attached together, then there’s an open someplace between the valve and the control, possibly brought on by a faulty cable or cable connector. This error can only be discovered by using cable tracing equipment.
8. This last field wiring evaluation will determine shorts right into the ground. Along with the common being pumped, remove all the channel wires from the control. Insert the screwdriver into the floor (it could be required to wet the floor to guarantee a fantastic link). Twist the next lead into the channel wires and the typical one at one time. Every one of these dimensions must be over 700K (700,000) ohms. Wire tracing equipment ought to be employed to find the issue. Learn more about multimeters review.
9. Transformers may also be analyzed with a multimeter. Connect the meter contributes to the main winding, in other words, the transformer input cables or plug. You may either find a resistance reading or an open. A resistance reading indicates the inner windings are undamaged, an open signifies that the swimmer’s internal fuse is poor and the transformer has to be substituted. The secondary winding, the transformer output signal, is analyzed the exact same manner. Connect the meter contributes to the output signal wires. An open signals that the transformer has to be substituted. The 20 – 60-ohm principle doesn’t apply to transformers. It’s normal to find immunity as low as 3 ohms.
10. A multimeter might also be utilized to ascertain which sort of battery should be utilized at a rotational control. There are just two battery connectors, a big one (feminine) and a bigger one (man). Twist the red probe into the huge connector, then the black probe into the little connector. If the control is intended to take an alkaline battery, then the scanning will probably be near zero volts. When it’s intended to take a rechargeable NiCad battery, then the scanning will probably be between 7 and 13 volts DC. Never use an alkaline battery at a control designed to take a rechargeable battery.
Articles Source: http://www.rainbird.com/landscape/resources/articles/Multimeters.htm