Water Level Control Troubleshooting
Learn how to troubleshoot your water level controls here.
1.Failure of the relay to change the state whenever a liquid touches the probes. (Condition has shown that the electrodes are dry.)
- Check the electrode connection- are there shorts?
- Check the electrodes to ensure that they are clean.
- Check the wiring between the probes and relay for continuity and correctness.
- Ensure that the liquid is touching the electrodes.
- Does the supplying voltage match the control voltage?
- Is the sensitivity correct for the liquid being used? The relay may not be sensitive enough for media.
- Is the media conductive? Hydrocarbons such as solvents, oil, and gasoline are not conductive.
- What is the load that is being switched? If the load is exceeding what the control is listed for, the contacts may have fused.
- Ensure that the distance between where the control is mounted and the tank is exceeding the distance parameters.
- Ensure that the high electrodes are not further than 4 feet from the reference electrode. If the application is like this, drop another reference electrode next to the highest probe. Then connect another reference probe to ground reference. This will also apply if the control is being used at single point level services (which just uses G and H probes) if the ground reference is more than 4 feet, the signal could be lost.
2.The control falsely triggers (Condition states electrodes are wet.)
- Check for any type of intermittent shorts that have been caused by any type of buildup over the insulator on the underside of the probe housing.
- Check the wiring between the probes and relays for continuity and correctness.
- What is the load that is switching? If the load has exceeded what the control has been listed for, the contacts may have fused.
- Is there the correct sensitivity for the liquid that is being used? The relay could be too sensitive for the media.
- Check to ensure that the ground reference isn’t shorting to sensing electrodes. This shorting may happen:
- In foaming applications where the foam acts as a media and it bridges from one probe to the other. The solution would be to ad heat to shrink the electrodes.
- One probe is touching the other.
- There is water in the conduit.
3.The control is triggering sporadically or intermittently on its own
- Is there a sloshing in the tank? Such as a float, the liquid could slosh off and on the probe, which causes it to trip off and on.
- Is the control mounted within a panel, which is using variable frequency drive (VFD)? The VFD is a pump control that can create an Electromagnetic field(EMF). If the VFD is used, move the control from it.
- Is the control wiring running too close to anything that may cause EMF? If yes, then move it.
- Are the control wires that have connected to the electrodes or level switch sharing a conduit that has high power wires? Such as more than 120 volts. If it does, this can create EMF. If this is created, then the control could be susceptible to a false tripping. The solution would be to run the control wiring with a shielded cable or in a dedicated metal conduit.
Testing procedures for all electronics
It is vital to isolate the controls from the electrodes and fittings. By being able to isolate it, you can then find out what the issue with the control is or if the issue is with the sensor. In order to do this, simply disconnect the wires that are running to the electrodes and to the fitting. Then disconnect the wires that run to the contacts that are running the load, this is normal for N.O. and N.C.
If you are ready to test the control, you should keep in mind what type of control that you have and what the operation mode is and if it happens to be a single point level service or differential level service. Ensure that you have checked if the controls have delays and ensure that the customer will wait long enough for the control to change its state.
The test below will stimulate the media uncovering and covering of the electrodes by simply jumping the terminals. When you are speaking with the customer, it is vital that you have the IO bulletin in order to match the right terminal numbers.
Single Point Direct Mode Control: Uses H and G electrodes
- Using a jumper wire, simply begin to jump from Terminal H to terminal G and the control will energize.
- Now, remove the wire jumper and then the control should then lose energy.
Differential Level Direct Mode Controls: Uses L, G, and H electrodes. (Normally in pump down applications)
- Using the jumper wire, jump from Terminal L to terminal G. Nothing should happen. This will prepare the control to latch.
- Keep the first jumper in place from L to G, then place another jumper wire from terminal L to terminal H. This control should now have energy.
- Next, remove the wire jumper from L to H. This control should stay energized.
- Remove the jumper from G to L. The control should not be energized.
Single point inverse mode control: Uses H and G electrodes
- Once the control has power that is connected to L2 and L1, the control should be energized. Using a jumper wire, being to jump from terminal H to G, and the control should then de-energize.
- Remove the jumper and then the control will become energized.
Differential level inverse mode control: Uses L, G, and H electrodes. (Normally used in fill applications)
- Once the control has power connected to the L2 and L1, the control will become energized. Using a jumper wire, begin to jump from terminal L to G. Nothing will happen. This will prepare the control to latch.
- Keep the first jumper in place from L to G, then place another jumper wire from terminal H to L. The control will not have energy to it.
- Remove the jumper from L to H and the control will not have energy to it.
- Remove the jumper from G to L.
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