Galltec+mela TFK80J Manuel de démarrage rapide - Page 4

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Checking calibration

It is possible to use sensor checks in order to test the humidity sensors from time to time for accuracy. The physical

process is described in detail in DIN 50 008, IEC Publikation 260, ISO/R 483-1966. In the air space above an aqueous

saturated saline solutaion an ambient climate is formed whose air humidity is dependant on the water vapour pressure

of the saline solution.

The Galltec+Mela sensor checks are designed so that a foil permeable to vapour is positioned between the saline solution

and the air space (space in which the measuring element is located). This makes carrying out the sensor checks a very

straightforward procedure as follows:

Remove the protective cap of the sensor check

while opening the PG screw and introduce

the sensor duct up to the mark. Tie the sensor

in the PG screw. Please make sure that the

sensor check is well tight and air-sealed while

caring out your measurement. If you are using

a sensor with a "Polyga" measuring element,

ensure particularly that the lid of the sensor is

well tight and that the cable duct is well sealed.

After a certain period of time, a constant humi-

dity builds up between the saline solution and

the air space in which the humidity measuring

element is located. Depending on the type of

saline solution and the sensor check, humidity

values range from 33%RH to 98%RH. The stan-

dard values of the Galltec+Mela sensor checks

are 33%RH, 55%RH, 76%RH and98%RH. We

recommend a compensation period of about 2 hours. Please ensure that there are no major fluctuations in temperature

during this period. Temperature fluctuations severely disturb the equilibrium.

The equilibrium moisture content is dependent on the temperature - according to the type of salt. The corresponding values

are given in a correction table located on the sesnsor check.

It is important that you replace the sealing cap of the sensor check after use, otherwise the water of the saline solution will

evaporate and the check will become unusable.

Guide to installation

Interference is often to be encountered during installation. The correct installation procedure can prevent interference to

a very large extent. However, some ground rules should be observed.

To avoid interference, suppression should be carried out in accordance with VDE 0875 and VDE 0874

(VDE - this is assumed to be the Vorschriftenwerk Deutscher Elektrotechniker - regulations governing German

electrical engineers).

Fundamentally, interference must be removed at its source, where suppressor material is most effective. Interference can,

however, also result from electromagnetic fields via signalling lines. The EMV law determines the corresponding protective

measures. All Galltec+Mela equipment is designed in accordance with European standards EN 50081-2 and EN 50082-2

(for industrial locations). In addition, further protective measures must be observed.

Unavoidable sources of interference should be kept at a good distance from the control systems.

Data and signalling lines should not be used in parallel with control, networking and power lines.

For data and signalling lines, shielded cable should be used, and the shielding must be applied to the earth

terminal. Ensure that earth circuits and fault currents do not arise as a result of a second earth connection.

For equipment with a network connection, it is recommended that a separate network circuit is used.

During the switch process, electrical power consumers such as switch contactors, magnetic valves etc. pro-

duce induction voltages that can cause interference. In the trade there is an abundance of protective and

suppressor component parts that are most effective when applied directly to the source of the trouble. A

suitable suppressor has the added advantage that components such as relays, microswitches etc. have a

longer service life.

Further difficulties during installation can arise if signalling lines are joined together with common lines. It is essential to

check whether this is permissible. Interference is particularly likely when installing using equipment of different makes.

Here, too, the trade offers isolating amplifiers that overcome the problem.

Sensor check

°C

33%rh

%rh

Screw the check firmly onto the humidity sensor. Wait for 2 hours. Ensure that the temperature is

kept constant. Take humidity reading according to temperature.

Sensor check

°C

55%rh

%rh

Screw the check firmly onto the humidity sensor. Wait for 2 hours. Ensure that the temperature

is kept constant. Take humidity reading according to temperature.

Sensor check

°C

76%rh

%rh

Screw the check firmly onto the humidity sensor. Wait for 2 hours. Ensure that the temperature is

kept constant. Take humidity reading according to temperature.

FK80_e page 4