Aplisens SGE-25C Посібник користувача - Сторінка 11

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5.7. Construction Materials: (for whole probes).

Diaphragm:

Sensing module:

Casing for electronic parts:

Liquid filing the interior of the sensing module:

Cable shield:

Additional cable shield:

5.8. Ingress protection rating:

SGE-25.SMART, SGE-25S.SMART, SGE-25, SGE-25S, SGE-25C and SGE-16

6. TECHNICAL DESCRIPTION.

6.1. Principles of Operation

The hydrostatic level probes work by converting changes in the resistance of a piezoresistive bridge, while are

proportional t the pressure (of a hydrostatic column of liquid), into a standard current output signal. The active

sensing device is a silicon diaphragm with in-diffused piezoresistors. The (non-uniformized) electrical signal

obtained from the piezoresistive bridge is proportional to the input pressure (depth) and is converted by the

electronic circuit into an output signal.

6.2. Construction.

6.2.1. The probes are in the shape of a hermetically closed cigar, containing the active sensing device with

silicon and sealing diaphragm, as well as a plate with the electronic components.

The SGE-25S.SMART and SGE-25S probes additionally fitted with a diaphragm seal enabling depth

measurements to be carried out on dense media and media with suspended matter and impurities, such as

liquid waste (fig. 1, 3).

The output signal is passed through a special cable with a capillary used to connect the negative side of the

measuring diaphragm to the atmosphere. All metal parts of the probes are made of 00H17N14M2 stainless

steel (316L), and Hastelloy C276 (see section 5.7.), and the cable has a polyurethane shield.

6.2.2. Special versions of the probes can be produced with cables shielded by an additional teflon layer.

The shield covers the parts of the cable while is immersed in the medium being measured, as well as a

necessary additional segment.

The Teflon shield (in Ex version) is additional equipped in stainless steel cord escorted electrostatic charges

(see fig. 4.).

6.2.3. The probes are fitted with elements ensuring excess voltage protection: „transil" diodes between the

wires, and plasma surge arresters between the wires and the casing.

(The plasma surge arresters not included in Ex versions.)

6.3. Electronic circuit of the probes

Electronic circuit can be produced in two versions:

6.3.1. The digital version (SGE-25.SMART and SGE-25S.SMART probes).

The electronic circuit changes the signal from the sensing module into digital signal and input to a

microprocessor , which controls the probe's operation. Using data input during the production process, the

processor processes the conversion curve, adjusts for thermal errors and carries out linearization.

After processing, the digital signal is again converted into an analogue 4÷20mA current signal, with a

superimposed digital communication signal.

For communication with the probe via the signal line a special Aplisens communicator KAP is used.

6.3.2. The analog version (SGE-25, SGE-25S, SGE-25C and SGE-16 probes).

The electronic circuit changes the signal from the sensing module into an output signal 4...20 mA.

The electronic circuit is equipped in protective elements assured Intrinsic safety and resistance on electric

impulse.

The electronics board is hermetically flooded hardenable silicone resin in the stainless steel casing.

Stainless steel 316L (00H17N14M2)-for SGE-16, SGE-25S, SGE-25S.SMART

Hastelloy C276 – for SGE-25, SGE-25.SMART, SGE-25C

Stainless steel 316L (00H17N14M2)

Steel pipe, 316L (00H17N14M2)

Silicone oil

polyurethane

Teflon (fitted by arrangement)

DTR.SG...04

(ENG)

IP68