DC4000/DC4500 Conductivity Controller Troubleshooting (con't')

5. Connect the 4-pin cable of the probe back to the controller unit. Remove the probe from the installation ‘T’ and use the paper clip to test continuity across the two pins of the probe. Touch one end of the paper clip to each pin on the probe being cautious to not scratch the pins. This should give a full-scale reading as well. It may be anywhere between 15,000 and 20,000 uS. If the reading you get is not between this range, use Emory Cloth or a mild abrasive, such as Soft Scrub to clean the end of the probe. If looking at the bottom of the probe, you will see two pins. If looking at a clock and the pins were located at 9 and 3 o’clock, you should scrub in the direction of 6 and 12 o’clock. This will prevent the possibility of scoring a line in the pin that could result in an electrode jumping from one pin to the other resulting in a false conductivity reading.

• Electrical interference with the probe signal. Is the probe cable run in any conduit with any other higher voltages?
• Is the probe cable near another high electrical source, (i.e.- near a large motor or power source, maybe on the other side of the wall where the probe cable is run)?
• Is the probe cable shielded or a twisted pair cable? (Probe cables and other low voltage signals should be run in 22AWG shielded or twisted pair cable. If a shielded wire is used, only one end of the shield should be connected to a grounding source. If both ends are connected, it will act as a giant antenna and, like a magnet, draw in any electrical interference. Signal wires can be run perpendicular to a higher voltage but never in parallel with them and code in most states require different conduit be used for high and low voltage signals. Check with local regulations for your area.)
• Is there a ground loop in the system? If so, the source of the ground loop will need to be located and repaired. This can cause erroneous conductivity readings. A ground loop can be caused by a voltage leak or faulty wiring of a motor that is grounded to an Earth Ground connected to the piping system. That voltage can then travel through the system using the water as its means of continuity. This can effect conductivity readings and possibly probe life.
• Is air trapped in the system? Air can cause the conductivity reading to jump all over the place. Verify that the loop is clear of any possible air bubbles.