6
4.2 Function
The EWLI-3B level indicator works on the basis of the conductive fill level method of measurement
whereby the electric conductivity of the medium is used. The conductivity of the medium is
measured in µS/cm. For the secure functioning of this method of measurement a minimum
conductivity of the substance to be measured is required.
The conductive method of measurement makes two statements: electrode submerged or electrode
emerged.
The measuring unit (MU) feeds and evaluates the installed probes (2 to 32 in number). The state of
the probes attached in the add-on housing is then sent to the control unit (CU).
The control unit (CU) determines the reactions necessary from the received data from the measuring
unit (MU).
System status
LCD display
LEDs
1*
4 mA .. 20 mA
Output contact
2*
Correct
operation
IGEMA
EWLI3-CU
4mA +
(16 mA / number of probes fitted)
x
Number of probes submerged
3*
A: activated
F: activated
Z: depending on assignment /
programming
correct operation
with failure of one
24V supply
4*
(40) PIN 1
power too low
5*
4mA +
(16 mA / number of probes fitted)
x
Number of probes submerged
3*
A: activated
F: activated
Z: depending on assignment /
programming
System error
(65) MU
CANBUS no data
5*
2 mA
A: no power / state of rest
F: no power / state of rest
Z: all without power
Water level
alarm
(LLW / HHW)
(33)
LLW alarm
5*
4 mA + x (LLW)
20 mA ‒ y (HHW)
x, y corresponding to
programmed Probe
A: no power / state of rest
F: activated
Z: depending on assignment /
programming
Water over steam
(“No”) please
check probe: “No”
5*
2 mA
A: activated
F: no power / state of rest
Z: depending on assignment /
programming
Probe error
7*
(LLW / HHW)
(33)
LLW alarm
5*
2 mA
A: no power / state of rest
F: no power / state of rest
Z: depending on assignment /
programming
