ROTRONIC ATEX - Manual (Page 13)

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3.2 Humidity transmitter
Two wire system
4...20mA = 0...100 %rh
Connection via Zener barrier Z788.H
- Max. cable length between intrinsically safe transmitter and
signal working up = 200m
- Cable for the connection of the intrinsically safe transmitter
with the Zener barrier: ET-7018
- Connection and type of the Zener barrier to be used
according to block diagram
Schematic diagram
Earthing rod
(Potential balance)
Ex zone Safe zone
+26V max.
U
A
0
4...20mA
3.3 Temperature transmitter
Two wire system
4...20mA = 0...100 °C
Connection via Zener barrier
Schematic diagram,wiring diagram and Zener barrier same as for humidity transmitter.
4. Start up
All ROTRONIC industrial transmitters are adjusted in the factory. Therefore a check of the equipment after mounting is not needed.
The devices are ready - to use immediately after installation.
4.1.Sensor protection
For the reliable use under more difficult conditions (pollution, higher airspeed), different filters are available.
Allowed airspeed with:
slotted cap
up to 3 m/s Order No.
wire mesh filter up to 20 m/s Wirefilter element SP-M15
teflon or polyethylene filter up to 20 m/s Steelsinter filter element SP-S15
steel sinter filter up to 40 m/s Teflonfilter element SP-T15
5. Sources of errors
Humidity measuring values can be affected by the following influences :
- Temperature errors
due to too short acclimation, cold outer wall, air draft (e.g. ventilators) insolation etc.
- Humidity errors
due to steam, water splashes, dripping water or condensation on the sensor etc., but reproducibility and long-term stability are not
impaired by this, even if the probe has been exposed for a lengthy period to high humidity or saturation with water vapour.
- Contamination
due to dust in the air. This can be largely avoided by using a corresponding filter (see 4.1). Clean or replace the filters periodically
depending upon the degree of contamination of the measuring site.
The sensor is insensitive to chemicals as far as they occur in usual concentrations (MAK values).
At higher concentrations or possible contact with liquid chemicals, the manufacturer must be consulted
in any case (MAK values = maximum work place exposure).
A
Zener barrier Z788.H