You will find below some microwave moisture measurement questions which are often raised and that may be simply rectified. Please check here if you have a problem. If your question is not below, please contact your supplier or our Technical Support Engineer.

SENSORS - GENERAL

Yes, they may be. If your plant is in an area prone to lightning strikes, then it is important that you should take all the normal reasonable precautions which will minimise the chances of damage to the sensors and other electronic equipment associated with the plant. These measures would include providing a lightning conductor and ensuring that all associated steel structures are properly grounded.

For further information, please refer to Engineering Note: EN0024

Yes, unless the plant has been properly grounded. It is always recommended that you should disconnect the connector at the sensor.

The Hydro-Link software is not detecting our sensor, we know the sensor is OK.

SENSORS - HYDRO-PROBE II

This would indicate that the sensing face is (i) not positioned in the flowing material and/or (ii) there is a build up of material over the face of the sensor or (iii) the sensor is either incorrectly configured or the average/hold feature is not being correctly activated.

For further information to ensure the Hydro-Probe II is in the correct position and the measuring face at the correct angle, please refer to the installation section of the Hydro-Probe II User Guide.

A visual inspection inside the bin when empty will frequently highlight the situation.

Check that the configuration of the Hydro-Probe II is set appropriately for your application. For it may be that the Hydro-Probe II is set in ‘standard’ mode while being used in conjunction with a Hydro-View for example, where ‘compatible’ mode would be the correct configuration or vice versa, the Hydro-Probe II may be set in ‘compatible’ mode when it should be used in ‘standard’ mode.

I am using the Hydro-Probe II in compatibility mode with an Hydro-View and the reading is not changing.

You can check the configuration of the sensor using the Hydro-Link diagnostic software.

The default settings, which are recommended for normal use appear in Engineering Note EN0028.

SENSORS - HYDRO-MIX V

I am getting inconsistent readings mix after mix and sometimes get spikes on the signal.

This is possibly due to electrical noise on the plant and can normally be overcome by checking the following; Ensure that the cable shield is only connected at the sensor end and not at the control unit end, also it is worth checking that the plant earth bonding has not deteriorated or become insufficient due to the addition of extra site equipment.

I am using the Hydro-Mix V in ‘compatible’ mode with the Hydro-Control IV and the reading remains constant despite changing moisture in the mix.

Check all wiring connections and ensure that the 15VDC supply voltage is present at the connector which connects directly to the sensor. Then check that the 500 ohm resistor is correctly fitted across the analogue out and analogue return in the 6 pin Bulgin connector (male0 attached to the other end of the 4m sensor cable. If necessary, check the resistance of the resistor.

I have smashed several ceramics on my Hydro-Mix V sensors while in the mixer – why?

Damage to sensors occurs if the sensor is fitted too proud of the mixer floor. The paddles can catch the ceramic, causing damage. Alternatively, if the mounting hole is too large, it is possible for stones to sit in the recess. If these are struck by the paddle, this also can smash the ceramic. Care must be taken when cleaning the mixer to ensure that the ceramic is not struck while removing dry concrete around the sensor.

How can I check whether my sensor is working correctly?

You can very simply check the analogue output when the sensor is (i) exposed to air, (ii) with totally dry material in front of it, and (iii) with your hand firmly pressed against the sensor face simulating very wet material. Refer to the Hydro-Mix V User Guide section ‘Sensor output characteristics’.

The readings from my sensor are erratic and will not stabilise.

This may be caused by excessive erratic movement of the material in front of the sensor face. This is normally associated when mixing small quantities of material in relation to the capacity of the mixer. This may be remedied by either increasing the size of the mix, or by adjusting the filtering parameters to the sensor. See the User Guide supplied with your sensor, or click here to view downloads.

How do I know whether the filtering parameters set inside the sensor are suitable for use with my mixer?

The filtering parameters may be viewed using the Hydro-Link diagnostic software. Recommended values are given in the Hydro-Mix V User Guide ‘Configuring the sensor’

How may I reduce my mix cycle time?

By optimising the performance of your mixer. See the Hydro-Mix V User Guide ‘Installation of the sensor’, or the Hydro-Control V User Guide.

CONTROL EQUIPMENT – HYDRO-CONTROL IV AND HYDRO-CONTROL JR

The display on the Hydro-Control IV/ Hydro-Control Jr shows a spike at the start of a different recipe. Why is this?

As the control unit changes recipe, it also changes calibration, this can be seen by a change in the visual signal and can look like a spike.

The display on my Hydro-Control Jr indicates moisture reading above 0% when the sensors is uncovered (or in air), when operating in ‘CALC’ (calculation) mode. (With the Hydro-Control V software version)

This will be as a result of selecting a final ‘percentage target’ for a particular recipe that is higher than the actual moisture. This will correspondingly affect all readings by adding an offset equivalent to the difference between the final target value selected and the actual moisture content.

This, in fact, is not important and does not affect the ability of the Hydro-Control Jr to make the appropriate corrections to ensure a consistent end moisture content of your mix.