Outputs
Analogue Output
The ASLD 2200 has one analogue output that is directly proportional to the 0 to 100% digital
display. Under normal circumstances this relates to 4 mA with the sensor at the bottom of the
tank and 20 mA with the sensor at the water surface.
There is no need to make any field adjustments during commissioning. If during maintenance it
is felt that the 4-20 mA signal needs calibration this can be carried out using the 4 mA and 20
mA potentiometer adjustments.
To calibrate the analogue output connect a multimeter on it mA setting in series with the output.
The ‘motor up’ and ‘motor down’ controls can then be used to force the output to 4 mA and 20
mA as necessary.
If the ‘Up’ button is pressed at any time the 4-20 mA loop will go to 12 mA until the ‘Down’
button is pressed and the sludge blanket is detected.
Limit Relay
The ASLD 2200 is equipped with a relay that is normally open; when either the top or bottom
limit is reached this contact will close. Either or both top and bottom limits can cause this relay
to activate, links A and B are used to configure this feature.
It should be noted that the trip point is not adjustable.
Controls and Settings
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