Level Sensor - Grundfos LC 221 Manual De Instrucciones

Display (pos. 1)
The display shows all relevant operating data and fault
indications. The operation and fault indications are described in
section 7.1 Description of display.
Operating buttons (pos. 2)
The level controller is operated by the operating buttons placed
under the display. The functions of the operating buttons are
described in the table below:
Operating
Description
button
• go left in the main menu.
• go up in the submenus.
• decrease values in the submenus.
• confirm a selection.
• activate the submenus.
• reset the buzzer.
• go right in the main menu.
• go down in the submenus.
• increase values in the submenus.
Status LEDs (pos. 3)
The upper LED (green) is on when the power supply is on.
The lower LED flashes (red) in case of fault to make the fault
visible from a long distance and is thus an addition to the display
symbols and fault codes.
Selector switch (pos. 4)
Switch Description of function
The operating mode is selected by the
ON-OFF-AUTO selector switch which has three
different positions:
POS I:
Starts the pump manually. The operating time
protection is active and indicates alarm after three
minutes. Normal operating times are up to max.
25 seconds (MD) and 55 seconds (MLD).
POS O:
• Stops the pump when running and cuts off the
power supply to the pump. The three symbols
"Settings locked", "Information" and "Setup" will
be visible.
• Resets fault indications.
POS AUTO:
Automatic operation. The pump will start and stop
according to the signal from the level sensor.
8

4.2 Level sensor

The piezoresistive level sensor placed in the controller is
connected via a pressure hose to a pressure tube in the tank.
The screw cap where the pressure hose is connected includes a
condensate trap and a connection for a DN 100 tube. This tube,
the pressure tube, extends down into the tank. The rising liquid
level compresses the air inside the pressure tube and pressure
hose, and the piezoresistive sensor transforms the changing
pressure into an analogue signal. The controller uses the
analogue signal to start and stop the pump and to indicate high
water level alarm. The pressure tube is fixed underneath the
screw cap and can be taken out for maintenance, service and for
cleaning the inside of the tube. An O-ring ensures tightness.
Please note that the display cannot show 0 mm, even if the tank
has been completely emptied. This fact is related to the
measuring principles of the sensor.
As long as the pressure tube is not immersed in water, the
configured value for the distance (e.g. 84 mm) between the
bottom of the tank and the bottom edge of the tube is displayed.
The sensor starts working correctly when it is immersed in water.
When the pressure tube is immersed, the liquid will enter the tube
just a few mm (as long as there is no air leakage). The water level
in the tube will not follow the level in the tank because of the
pressure ratio inside the tube.
The sensor usually does not require any calibration in the field, as
it has already been calibrated by the factory.
Fig. 5 Pressure tube with pressure hose
Please note that the pressure tubes look differently in Multilift and
Uno-/Duolift. Multilift lifting stations have a DN 100 tube with a
screw cap, whereas Uno-/Duolift come with a DN 50 tube with a
cap to be inserted.