Application and function
The electronic switch consists of the following components:
- Water column with 1 to 4 probes (fully wired)
- Measuring unit (MU); mounted on to the water column housing and fully wired
- NEMA4X/IP66 Control Box with Control unit (CU) for up to 4 independent probe channels and LED indication (fully wired)
- connecting cables
Technical basic equipment
The state of the art electronic level detection can be used for steam boilers or any other application with electrically conductive liquid. Typical applications:
- Receiver tanks (Water tank, Deaerator, Condenser)
- Flash Tanks, Feedwater heaters
- TWIP (Turbine water induction prevention)
- Steam line drain control
- Boiler water high level high/low level control and many more
Recording is carried out by a conductive measuring principle which can detect even lowest condutivities. The measuring unit (MU) can be equipped with up to 4 probes. The distance between the individual probes can be determined by the customer. Due to the freely programmable assignment of switch contacts to the probes, the system provides maximum versatility.
Both the measuring unit and the control unit have two independent electronic circuits with its own processors. All processors carry out regular self-tests for internal faults in the electronic circuit. Redundant power supplies are standard with our system.
The control unit (CU-3) processes the signals recorded and controls the downstream functions. It is built into a stainless steel control box (IP65/NEMA4X). The control box provides local indication of all probes (water=green, steam=red), normal operation (green LED) and system fault (yellow).
Individual configurable output contacts (SPDT) with time delay option are available as standard. Furthermore an eighth contact (SPDT) is permanently switched as the signal contact for device error and a ninth contact (SPDT) permanently switched as the water level alarm contact, whereby the probes triggering the alarm (LW and/or HW) can be freely selected.
Here each processor actuates its own relay per contact whereby the output contacts are only switched when both processors signal normal operation. In addition there is a 4mA ‒ 20mA interface as a (virtually) continuous output available. The output is increased per submerged probe by the corresponding proportion (16 mA / number of probes). In the event of an error the output goes to 2 mA.
The configuration/programming is carried out via 4 buttons and a 2-row illuminated LCD display with 16 characters each. Also the LCD display will show local fault indication such as power supply failure, probe fault, level indication failure (“water over steam failure”), circuit board failure, cable fault or short circuit.
The EWLS design and fabrication complies with EU Directive 2014/68/EU and the applied regulations DIN EN 12952, DIN EN 12953, AD2000 and the ASME boiler code.