Lumel P18 User manual

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USER’S MANUAL
TEMPERATURE
AND HUMIDITY
TRANSDUCER
P18 TYPE

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CONTENTS
1. APPLICATION ........................................................................... 5
2. BASIC REQUIREMENTS, OPERATIONAL SAFETY................ 5
3. INSTALLATION .......................................................................... 5
3.1. Assembly ............................................................................................5
3.2. Electrical Connections ........................................................................7
4. SERVICING ................................................................................ 9
4.1. Functions of the P18 Transducer ......................................................10
4.2. Individual Characteristic of Analog Outputs ...................................... 11
4.3. RS-485 Interface ...............................................................................13
4.4. Standard Parameters ........................................................................18
5. ACCESSORIES ........................................................................ 19
6. TECHNICAL DATA ................................................................... 20
7. ORDERING CODES ................................................................. 23
8. MAINTENANCE AND GUARANTEE ....................................... 24

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1. APPLICATION
The P18 transducer is device destined for the continuous measurement
and conversion of relative humidity and ambient temperature into a
digital form and into a voltage or current standard signal. The transducer
is fixed on a wall. The programming of the transducer is possible by
means of the RS-485 interface.
Applied sensor shields enable the application of the P18 transducer in
various ambient conditions
2. BASIC REQUIREMENTS, OPERATIONAL SAFETY
In the security scope, the transducer meets the requirements of the
EN 61010 -1 standard.
Remarks Concerning the Operator Safety:
1. General
- All operations concerning transport, installation, and commissioning as
well as maintenance must be carried out by qualified, skilled personnel
acc. to the section 3.2. of the user’s manual.
- According to this basic safety information, qualified, skilled personnel
are persons who are familiar with the installation, assembly, commis-
sioning, and operation of the product and who have qualifications
necessary for their occupation.
- In order to avoid any damage, before switching the supply on, it is
recommended to ensure that all wires were correctly connected.
When unpacking the P18 transducer, please check whether the type
and version code on the data plate correspond to the order code.
3. INSTALLATION
3.1. Assembly
The P18 transducer is designed to be mounted on a wall by means of
a screw connection or glue without the loss of IP65 tightness .
The transducer housing is made of a self-extinguishing plastics.
Housing dimensions: 64 x 58 x 35 mm.
The transducer has screw connectors placed inside the transducer,
which enable the connection of external wires of 1 mm2cross-section.
Overal dimensions and the fixing way are shown on the fig. 1.

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Fig.1. Overall Dimensions of the P18 Transducer
Fig.2. Lay-out of Assembly Holes of the P18 Transducer

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3.2. Electrical Connections
The P18 transducer has 8 connecting terminals to which there is access
after removing the cover of the transducer housing.
For electrical connections, one must use a round wire with external dia-
meter from 3.5 mm up to 6 mm.
Before the transducer assembly, one must pass supplying wires through
the packing. Twist the packing seal in order to obtain the leaktightness.
If the packing seal is not twisted, we cannot ensure the required IP 65
leaktightness.
Fig.3. Marking of Terminals for the Connection of External Signals

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Way of Electrical Signal Connection Table 1
Transducer
without analog outputs
Transducer
with current outputs
Transducer
with voltage outputs
One must use a spiral for the interface line connection. In case of the
transducer work in an environment with high interference, one must
apply shielded wires. The shield must be connected to the nearest PE
point from the feeder side.

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4. SERVICING
After connecting wires, closing and servicing the housing, and connecting
to the supply, the transducer is ready to work with manufacturer’s settings
(table 8).
The transducer can be programmed through the RS-485 interface.
One can program following parameters in the transducer:
- communication parameters
- averaging time of the measurement,
- individual characteristics of analog outputs
(for executions with analog outputs).
There is the possibility to connect the transducer through another trans-
mission media, like: ETHERNET, USB, using LUMEL S.A.’s converters.
The transducer is equipped of one two-colour signalling diode.
The diode pulsation means:
- pulsing in green colour – measurements carrying out correctly,
- pulsing in red colour – correct communication through the RS-485
interface.
The diode pulses only during 3 min. since the supply switching on or
the change of transmission parameters, e.g. after shortening with the
ZW jumper.
4.1. Functions of the P18 transducer
- calculation of chosen physical quantities (dew-point temperature,
absolute humidity),
- conversion of measured quantities into an output signal on the base
of the individual linear characteristic,
- memory storage of maximal and minimal values for each of the mea-
sured and calculated value,
- programming of the measurement averaging time,
- RS-485 interface servicing in the MODBUS protocol, in RTU mode.

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- absolute humidity
where:
T = temperature [oC]
RH = relative humidity [%]
Td= temperature of the dew-point [oC]
Pws = pressure of the satured water vapour
(water vapour pressure) [mbar]
a= absolute humidity [g/m3]
Measured and calculated values of the P18 transducer:
- temperature T = measured
- relative humidity RH = measured
- dew-point
a = 2,1668 ¬Pws ¬RH
100 ¬(T+ 273,2)
Td= Tn
m-1
log (Pws ¬RH
10000 ¬A
)
Coefficients for the dew-point Table 2
TAmT
n
< 0 oC 6.119866 7.926104 250.4138
0...50 oC 6.1078 7.5 237.3
50...100 oC 5.9987 7.3313 229.1
4.2. Individual Characteristic of Analog Outputs
The P18 transducer in execution with analog outputs enables the
conversion of measured quantities into an output signal on the strength
of individual linear characteristic of analog outputs. On the base of