Danfoss AKS 41 Liquid Level Transmitter
Publication 9-45
Section 9
Page 14 of 18
Issue 1 : 10/11
1. FAULT: An output signal between 4 to 20 mA is measured but the current does not match the actual liquid level
Probable Cause
Remedy
Level transmitter not set to the correct refrigerant.
Set the transmitter to the refrigerant; refer to 6.
If the level transmitter is mounted in a standpipe, there may
reasons not directly connected to the transmitter/level
controller why the liquid level in the standpipe is not the
same as that in the vessel containing the refrigerant.
Check that stop valves connecting the standpipe to the
vessel are fully open. For applications using R717, check for
oil logging in the standpipe; refer to 8.
Level transmitter incorrectly calibrated.
Recalibrate the level transmitter. Calibrate the lower limit
first (refer to 6.2.1) then see if whether the transmitter
measures correctly.
2. FAULT: Output signal current is 0 mA
Probable Cause
Remedy
If the preliminary checks have been carried out correctly and
an output signal still cannot be measured, the level
transmitter is defective.
Fit a new liquid level transmitter.
3. FAULT: Output signal current is 2 mA (red LED is illuminated – early versions)
Probable Cause
Remedy
The transmitter is measuring a liquid level lower than the
point calibrated as the minimum level (4 mA point). This can
happen if the rod is periodically completely out of the liquid.
Recalibrate the 4 mA point while the transmitter is out of the
liquid.
4. FAULT: Output signal current is constant 4 mA
Probable Cause
Remedy
Green LED ‘flashing’ (red LED also ‘flashing’ – early
versions). The transmitter is in setting mode.
Interrupt the supply voltage for about 10 seconds to restore
the transmitter to normal operation.
Green LED extinguished (red LED ‘flashing’ – early
versions). The transmitter is in calibration mode.
Early versions only – remove the shorting strap from across
the two pins and store by placing over one of the two pins.
Green LED ‘flashing’ (red LED also extinguished – early
versions). The transmitter is operating normally and
registers that the liquid level is below the lower end of the
rod.
Check that the liquid level is able to rise (valve closed, oil
logging etc).
5. FAULT: Output signal current is 22 mA (red LED is illuminated – early versions)
Probable Cause
Remedy
The transmitter is measuring a liquid level higher than the
point calibrated as the maximum level (20 mA point).
Check if the liquid level is abnormally high, i.e. beyond the
transmitter’s normal measuring range. Check that the
transmitter is set to the correct refrigerant. If the error is not
found here, recalibrate the transmitter.
Table 2 Common Faults and Remedies
10.
Spares
In the event of a fault, if the problem is traced to the AKS 41/AKS 41U
itself rather than faulty wiring, liquid level controller etc, the only option is
to replace the liquid level transmitter.
Obtain a new AKS 41/AKS 41U from the address below, quote the
nomenclature code that can be found inside the transmitter housing:
J & E Hall International
Telephone: +44 (0) 1332-253400
Hansard Gate,
Fax: +44 (0) 1332-371061
West Meadows,
E mail: [email protected]
Derby,
Website: www.jehall.co.uk
DE21 6JN
England
