Testo 6781 Operating Manual
testo 6781 · Transmitter
P2A software · Parameterizing, adjusting and analyzing
Instruction manual
2
1 Safety and the environment
Pos: 1 /TD/Überschriften/MUF/Sicherheit und Umwel t @ 3\mod_1234793958627_79.doc @ 26223 @ 1
1 Safety and the environment
Pos: 2 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/MUF 63xx/Elektrische Gefahren vermeiden @ 3\ mod_ 1234 794609299_79.doc @ 26280 @ 5
Avoiding electrical hazards
> Never use the instrument and connected probes to measure on
or near live parts!
> Damaged mains cables must only be replaced by authorized
personnel.
> Only have the transmitter wired and connected by authorized
personnel with the voltage disconnected.
> You must always comply with the regulations applicable in your
Pos: 3 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/MUF 63xx/Personen- und Sachschäden vermeiden @ 3\ mod_1234794744768_79.doc @ 26299 @ 5
country for opening and repairing electrical equipment.
Avoiding personal injury and damage to equipment
> Installation, setting and calibration work must only be carried
out by qualified and authorized personnel!
> Only open the instrument when this is expressly described in
the instruction manual for installation, maintenance or repair
purposes.
> Observe the permissible storage, transport and operating
Pos: 4 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/Nicht mit Lösungsmitteln lagern @ 0\mod_11756923 75179_79.doc @ 583 @
temperature.
> Do not store the product together with solvents. Do not use any
Pos: 5 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/MUF 63xx/Bei Wartung MUF nicht zur Regelung verwende n @ 3\ mod_1234794852377_79.doc @ 26318 @
desiccants.
> Do not use the instrument for control purposes at the same time
Pos: 6 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/Produkt bestimmungsgemäß verwenden @ 0\mod_11737 81261848_79.doc @ 386 @
as operating or servicing the transmitter.
> Only operate the product properly, for its intended purpose and
within the parameters specified in the technical data. Do not
Pos: 7 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/Nur beschriebene Wartungsarbeiten durchf ühren @ 0\mod_1175692705195_79.doc @ 601 @
use any force.
> Carry out only the maintenance and repair work on this
instrument that is described in the documentation. Follow the
prescribed steps exactly. Use only original spare parts from
Pos: 8 /TD/Sicherheit und Umwelt/Sicherheit gewähr lei s ten/MUF 63xx/Fachpersonal @ 3\mod_1234794940409_7 9.doc @ 26337 @
Testo.
Any additional work must only be carried out by authorized
personnel. Otherwise testo will not accept any responsibility for the
proper functioning of the instrument after repair and for the validity
of certifications.
3
2 About this document
Pos: 9 /TD/Überschriften/MUF/Umwelt schützen @ 3\mod_ 123 4858757571_79.doc @ 26363 @ 5
Pos: 10 /TD/Sicherheit und Umwelt/Umwelt schützen/Pr odukt entsorgen @ 0\mod_1173780307072_79.doc @ 357 @
Protecting the environment
> At the end of its useful life, send the product to the separate
collection for electric and electronic devices (observe local
Pos: 11 /TD/Überschriften/MUF/Zu diesem Dokument @ 3\mod_ 1234793991331_79.doc @ 26242 @ 1
2 About this document
Pos: 12 /TD/Sicherheit und Umwelt/Zu diesem Dokument/Ver wendung (Standard) @ 0\mod_1173775068554_79.doc @ 337 @ 5
regulations) or return the product to Testo for disposal.
Use
> Please read this documentation through carefully and
familiarize yourself with the product before putting it to use. Pay
particular attention to the safety instructions and warning advice
in order to prevent injuries and damage to the products.
> Keep this document to hand so that you can refer to it when
necessary.
> Hand this documentation on to any subsequent users of the
Pos: 13 /TD/Sicherheit und Umwelt/Zu diesem Dokument/Sy mbole und Schreibkonventionen/Warnhinweis W ARNUNG @ 2\mod_1207646966234_79.doc @ 14398 @
Pos: 14 /TD/Sicherheit und Umwelt/Zu diesem Dokument/Sy mbole und Schreibkonventionen/Warnhinweis VORSIC HT @ 2\mod_1207651416515_79.doc @ 14416 @
Pos: 15 /TD/Sicherheit und Umwelt/Zu diesem Dokument/Sy m bo le und Schreibkonv. Software [Standard] @ 0\mod_11902 0333 2543_79.doc @ 4883 @ 5
product.
WARNING
CAUTION
Indicates potential serious injuries
indicates potential minor injuries
Symbols and writing standards
Representa-
Explanation
tion
Note: Basic or further information.
1. ...
2. ...
Action: more steps, the sequence must be
followed.
> ... Action: a step or an optional step.
- ... Result of an action.
Menu
[OK]
Elements of the program interface.
Buttons of the program interface.
... | ... Functions/paths within a menu.
“...” Example entries
Pos: 16 /TD/--- Seitenwechsel --- @ 0\mod_1173774430601_0.doc @ 283 @
4
3 Contents
Pos: 17 /TD/Überschriften/MUF/Inhalt @ 3\mod_123479 4019831_79.doc @ 26261 @ 1
3 Contents
1 Safety and the environment....................................................................3
2 About this document...............................................................................4
3 Contents...................................................................................................5
4 Transmitter...............................................................................................8
4.1. Specifications ..................................................................................8
4.1.1. Functions and use ...........................................................................................8
4.1.2. Scope of delivery .............................................................................................8
4.1.3. Accessories .....................................................................................................8
4.1.4. Technical data .................................................................................................9
4.1.5. Dimensions....................................................................................................13
4.2. Product description........................................................................14
4.2.1. System components ......................................................................................14
4.2.2. At a glance.....................................................................................................15
4.2.3. Display and keypad........................................................................................16
4.2.4. Service interface............................................................................................16
4.2.5. Analog outputs...............................................................................................16
4.2.6. Parameters....................................................................................................16
4.2.7. Scaling .........................................................................................................16
4.3. Commissioning..............................................................................17
4.3.1. Mechanical assembly.....................................................................................17
4.3.1.1. Without stainless steel mea surement chamber and cooling coil........18
4.3.1.2. With stainless steel measur em ent chamber (max. 35,000 hPa)........19
4.3.1.3. With stainless steel measurement chamber and cooling coil (max.
35,000 hPa)......................................................................................19
4.3.1.4. Connecting voltage supply and analog outputs.................................20
4.3.1.5. Plug-in connection for power supply and channel.............................21
4.3.2. Adjusting the instrument ................................................................................21
4.3.2.1. Self-adjustment.................................................................................21
4.3.2.2. 1-point adjustment by entering a refere nce value..............................22
4.3.2.3. Analog output adjustment.................................................................23
4.4. Operation.......................................................................................24
4.4.1. Relationship between user menu and mini-DIN socket is active....................24
4.4.2. Password protection ......................................................................................24
4.4.3. Structure of user menu ..................................................................................24
4.4.4. Overview of the testo 6781 user menu...........................................................26
4.4.5. The individual main menus ............................................................................28
4.4.5.1. Editing main menu of channel 1........................................................28
4.4.5.2. Editing Main Menu Alarm..................................................................29
4.4.5.3. Editing Main Menu Settings ..............................................................30
4.4.5.4. Editing Main Menu Analysis..............................................................32
4.4.5.5. Editing Message main menu.............................................................34
5
3 Contents
4.4.5.6. Calling up Main Menu Ident..............................................................35
4.4.5.7. Editing Main Menu Adjust.................................................................35
4.4.5.8. Editing Reset main menu..................................................................37
4.5. Status, warning and error messages ............................................37
4.5.1. Status messages...........................................................................................38
4.5.2. Warning messages........................................................................................39
4.5.3. Transmitter error messages...........................................................................40
4.5.4. Handling alarm messages .............................................................................40
4.6. Maintenance and cleaning............................................................41
4.6.1. Maintaining the instrument............................................................................. 41
4.6.2. Cleaning the instrument.................................................................................41
5 Parameterizing, adjusting and analyzing software (P2A software) . . 42
5.1. Specifications................................................................................42
5.1.1. Functions and use .........................................................................................43
5.1.2. System requirements..................................................................................... 43
5.1.3. Scope of delivery...........................................................................................44
5.2. First steps ..................................................................................... 44
5.2.1. Installing the software/driver.......................................................................... 44
5.2.1.1. Installing P2A software.....................................................................44
5.2.1.2. Installing USB driver.........................................................................44
5.2.1.3. P2A software upgrade......................................................................45
5.2.2. Starting the software......................................................................................45
5.2.2.1. Starting the program......................................................................... 45
5.2.2.2. Establishing a connection wi th the instrument...................................45
5.2.2.3. Activating the connection w ith the instrument...................................45
5.3. Using the software........................................................................46
5.3.1. User interface................................................................................................46
5.3.2. Editing instrument/parameter file ...................................................................48
5.3.2.1. Changing instrument/parameter file..................................................48
5.3.2.2. Creating a new instrument file...........................................................55
5.3.2.3. Saving parameters............................................................................55
5.3.2.4. Opening the parameter file............................................................... 56
5.3.2.5. Copying and pasting parameters......................................................56
5.3.2.6. Deleting instrument/parameter file....................................................57
5.3.3. Analyzing/testing the transmitter....................................................................57
5.3.3.1. Analyzing/testing the instrument....................................................... 57
5.3.3.2. Carrying out factory reset..................................................................57
5.3.3.3. Testing analog output.......................................................................58
5.3.3.4. Displaying min./max. values..............................................................59
5.3.4. Adjusting the transmitter................................................................................60
5.3.4.1. 1-point adjustment............................................................................61
5.3.4.2. Adjusting the analog output.............................................................. 62
5.3.5. Transmitter history.........................................................................................63
6
3 Contents
6
Tips and assistance...............................................................................67
6.1. Questions and answers.................................................................67
6.2. Accessories and spare parts .........................................................67
6.2.1. Ordering options for testo 6781 transmitter (0555 6781)................................69
Pos: 18 /TD/--- Seitenwechsel --- @ 0\mod_1173774430601_0.doc @ 283 @
7
4 Transmitter
Pos: 19 /TD/Überschriften/MUF/1 Messumformer @ 3\ mod_1234258401060_79.doc @ 23894 @ 1
4 Transmitter
Pos: 20 /TD/Überschriften/MUF/1.1/2.1/3.1 Leis tungsbeschreibung @ 3\mod_1234258595211_79.doc @ 23951 @ 2
4.1. Specifications
Pos: 21 /TD/Leistungsbeschreibung/Verwendung/ MUF63xx/MUF 6781 @ 3\mod_1238162232871_79.doc @ 30254 @ 3
4.1.1. Functions and use
The testo 6781 transmitter was developed especially for low
dewpoint temperatures and is suitable for the following
applications, amongst others:
• Compressed air process engineering
• Clean-room technology
• Regulation and monitoring of compressed air driers
• Production and conveyance of gases
• Monitoring of humidity and temperature in medical compressed
Pos: 22 /TD/Leistungsbeschreibung/Lieferu mfang/ MUF 63xx/MUF 6781 @ 3\mod_1238162497483_79.doc @ 30275 @ 3
air or granulate driers
4.1.2. Scope of delivery
The scope of delivery of the testo 6781 transmitter includes the
following:
• Assembly accessories
• Operating instructions
• Calibration report
• CD-ROM with operating instructions (PDF) and P2A update
(this can only be used in conjunction with the P2A software,
Pos: 23 /TD/Leistungsbeschreibung/Lieferu mfang/ MUF 63xx/Zubehör Übersicht 635x @ 3\mod_1236084601953 _79.doc @ 27292 @ 3
which has to be ordered separately).
4.1.3. Accessories
The following accessories are available for the testo 6781
transmitter, amongst others:
• Mains unit
• P2A software (parameterizing, adjusting and analyzing
software)
8
• Assembly accessories
Information about accessories and their order numbers can
be found in Accessories and spare parts or on the
website at www.testo.com.
Pos: 24 /TD/Leistungsbeschreibung/Technische Dat en/MUF 63xx/MUF 6781 @ 3\mod_1238162594608_79.doc @ 30296 @ 3555 5555555555555555555555
4.1.4. Technical data
4 Transmitter
Parameter
1
• Dewpoint temperature
Measuring range at 25 °C
• -90 to 30 °C
td
Meas. uncertainty2
-20 °Ctd to -40 °Ctd: +/-1,5 K
-40 °C
-60 °C
to -60 °Ctd: +/-2 K
td
to -75 °Ctd: +/-2,5 K3
td
The measuring uncertainty increases with high flow values.
1
Above 0 °Ctd the dewpoint temperature is shown and below 0 °Ctd the frost
point temperature is shown. In rare cases at frost point temperatures between
-35 °Ctd and 0 °Ctd differences between the 6781 and a dew mirror hygrometer
may occur.
2
Expanded basic uncertainty (K = 2) at a process temperature of 25 °C.
Measuring uncertainty according to GUM (Guide to the E xpression of Uncertainty in Measurement):
ISO guideline for determining the measuring uncertainty in order to render global measurement results
comparable.
The following uncertainties are used during the inquiry:
• Hysteresis
• Linearity
• Reproducibility
• Adjustment area/factory calibration
• Test location
An additional uncertainty factor independent of the dewpoint temperature and
process of ±0.03 K x reading (in °C
) + 0.2 K x (25 °C - process temperature in
td
°C) results from this overall view
Outside the stated range, a measurement inaccuracy of +/-5K (typically) applies.
3
At process temperatures > 25 °C the lower limit of the measuring range
increases by 0.5 K/K. The uncertainty values are valid for the respective
measuring range.
9
4 Transmitter
Response time
≤ 3 s when changing from -75 °Ctd to -30 °Ctd
t
63
t
≤ 9 s when changing from -75 °Ctd to -30 °Ctd
90
t
≤ 300 s when changing from -30 °Ctd to -75 °C
63
td
t90 ≤ 1080 s when changing from -30 °Ctd to -75 °Ctd
Resolution
Measuring range Resolution
0 to 100 % RH 0.001
0.001 to 28 g/kg 0.001
0.01 to 194 gr/lb 0.01
0 to 31 g/m3 0.001
0.001 to 14 gr/ft3 0.001
1 to 42,500 ppm (vol) 1
-90 to 30 °Ctd 0.1
-130 to 86 °Ftd 0.1
-110 to 30 °C
-165 to 86 °F
0.1
tdA
0.1
tdA
-40 to 70 °C 0.01
-40 to 158 °F 0.01
10
Meas. cycle
• 1/sec
Interface
• Mini-DIN for P2A software (adjustment and parameterization
software)
Voltage supply
• 4-wire (separate signal and supply lines): 20 to 30 V AC/DC,
300 mA power consumption
4 Transmitter
Maximum load
• 4-wire: 500 Ω (power output)
Maximal load
• 4-wire: 10 kΩ (voltage output)
Analog output
• 0 to 1 V ± 1.5 mV (4-wire) or
• 0 to 5 V ± 7.5 mV (4-wire) or
• 0 to 10 V ± 15 mV (4-wire) or
• 0 to 20 mA ± 0.03 mA (4-wire) or
• 4 to 20 mA ± 0.03 mA (4-wire)
Resolution of analog output
• 12 bit
Display
• 2-line LCD with plain text line (optional)
Operating temperature without display
• -40 to 70 °C
Operating temperature with display
• 0 to 50 °C
11
4 Transmitter
Storage temperature without display
• -40 to 80 °C
Storage temperature with display
• -20 to 80 °C
Process temperature
• -40 to 70 °C
Application humidity
• 0 to 100 % RH
Pressure application range
• 50,000 hPa
Housing, weight
• Metal, 0.5 kg
Process connection
• G 1/2 or
• NPT 1/2"
12
Protection class
• IP 65 only if the transmitter is wired and/or sealing plugs are
inserted
Directives, standards and tests
• EC Directive: 2004/108/EC
• 6781 was manufactured in accordance with EC pressure
equipment Directive 97/23/EC, Article 3 Paragraph 3 as per
"sound engineering practice", taking the regulations to be
observed into account.
Warranty
• Duration: 2 years
• Warranty conditions: see website www.testo.com/warranty
Pos: 25 /TD/Leistungsbeschreibung/Technische Dat en/MUF 63xx/MUF 6781 Abmessungen @ 3\mod_1239806330094_79. doc @ 31183 @ 3
4.1.5. Dimensions
4 Transmitter
13
4 Transmitter
Pos: 26 /TD/Überschriften/MUF/1.2/2.2 Produktb esc hreibung @ 3\mod_1234258723551_79.doc @ 24008 @ 2
4.2. Product description
Pos: 27 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Systemkomponenten 6781 @ 3\mod_1239868226476_7 9. doc @ 31305 @ 3
4.2.1. System components
Application System components
With clean air and a process pressure
A
corresponding to the presetting of the
measurement chamber (1), a measurement
chamber (1) is required for the rapid
• 1: Measurement chamber
• testo 6781 with
G1/2 thread
assembly (without de-pressurizing the
installation).
With clean air and a process pressure
B
greater than or less than 7000 hPa (1000 to
35,000 hPa) that therefore does not
correspond to the presetting of the inflow
valve, a measurement chamber (1) with a
• 1: Measurement chamber
• 2: Flow meter
• testo 6781 with
G1/2 thread
flow meter (2) is required.
14
4 Transmitter
Application System components
For rapid assembly (without de-pressurizing
C
the installation), a measurement chamber (1)
is required. Connect a filter (4) upstream for
oily media.
• 4: Filter
• 1: Measurement chamber
• testo 6781 with
G1/2 thread
With dry air (max. 140 °C), a PTFE tube (3)
D
is used and the valve of the measurement
chamber (1) is opened to maximum (suitable
up to -60 °C
For process temperatures of 50 °C to 200 °C
E
).
td
and a process pressure corresponding to the
presetting, it is necessary to use a cooling
coil (5) and a measurement chamber (1).
Connect a filter upstream for oily media.
• 3: PTFE tube
• 1: Measurement chamber
• testo 6781 with
G1/2 thread
• Filter, if necessary
• 5: Cooling coil
• 1: Measurement chamber
• testo 6781 with
G1/2 thread
If A to E are not required. The thread is
F
screwed directly into the process.
De-pressurized tube required during
installation.
• testo 6781 with
G1/2 thread
or
• testo 6781 with N1/2"
thread
Pos: 28 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Auf einen Blick MUF 6781 @ 3\mod_1238165303035_79.doc @ 30317 @ 3
4.2.2. At a glance
1 Display (optio nal)
2 Keys (only with optional display)
3 Test contacts
4 M 16 x 1.5 screw connection,
e.g. analog output
5 Service flap with connection for
service plug
6 Screw connection with process
connection (G 1/2 or NPT 1/2")
7 Sintered cap over sensor unit
15
4 Transmitter
Pos: 29 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Display und Tastatur 6781 @ 4\mod_1250064749770_79. doc @ 47423 @ 3
4.2.3. Display and keypad
The display option allows operation of the testo 6781 transmitter via
the display and four keys.
The LCD display consists of one 7-segment line for displaying
readings and units and of an information line (for status messages,
for example).
The brightness and contrast of the display and the background
lighting (permanent or off) can be changed via the user menu or the
Pos: 30 /TD/Überschriften/MUF/1.2.x Servicesc hni ttstelle @ 3\mod_1237306891654_79.doc @ 29795 @ 3
4.2.4. Service interface
Pos: 31 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Serviceschnittstelle 635x @ 3\mod_12372173884 92_79.doc @ 29723 @
P2A software.
The parameterizing socket (mini-DIN) is located behind the service
Pos: 32 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Analogausgänge 635x @ 3\mod_1234774510463_79.doc @ 25726 @ 3
flap as an interface to the P2A software.
4.2.5. Analog outputs
As analog outputs, the testo 6781 has either
• 1 current output of 0 to 20 mA (4-wire)/4 to 20 mA (4-wire) or
Pos: 33 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Messgrößen 6781 @ 3\mod_1239284685066_79.doc @ 31095 @ 3
• 1 voltage output of 0 to 1 V/0 to 5 V/0 to 10 V (4-wire)
4.2.6. Parameters
The following parameters are displayed:
• Relative humidity in % RH (technical)
• Degree of humidity in g/kg and gr/lb
• Absolute humidity in g/m³ and gr/ft³
• Water content in ppm (vol)
• Dewpoint temperature in °C
• Standardized dewpoint (at atmospheric pressure 1013 hPa) in
°C
and °F
Pos: 34 /TD/Produktbeschreibung/Übersicht/ MUF 63xx/Skalierung @ 3\mod_1234775406989_79.doc @ 25783 @ 3
tdA
• Temperature °C and °F
tdA
and °Ftd
td
4.2.7. Scaling
There are three types of min./max. values:
1 The measuring range: The maximum sensor performance is in
this range. Values outside of the measuring range are displayed
via messages, for example.
16
2 Standard scaling: The output signals are assigned to this
measuring range as standard:
◦ during delivery if no entries are made in the order code
◦ after exchanging the unit, the measuring range recorded in
the instrument is applied as standard.
The transmitter even retains its scaling with the voltage
disconnected.
3 The maximum settings for the manual scaling
◦ The maximum limits can be calculated as follows:
X = difference between MIN. and MAX. value of the
standard scaling
(Max. value of standard) + (50 % of X)
(Min. value of standard) - (50 % of X)
◦ It is thus possible to scale beyond the measuring range, e.g.
for the adjustment of the scaling limits to standard values of
a PLC.
With the alarm definition, however, the physical measuring
Pos: 35 /TD/Überschriften/MUF/1.3/2.3 Inbetri ebnahme @ 3\mod_1234258805768_79.doc @ 24027 @ 2
4.3. Commissioning
Pos: 36 /TD/Erste Schritte/MUF 63xx/Mechanische Mon tag e 6781 @ 3\mod_1239807163104_79.doc @ 31204 @ 3444
range limits are decisive.
4 Transmitter
4.3.1. Mechanical assembly
• Carefully perform assembly work.
• Take special care with leaktightness. We recommend
inserting a metal sealing ring (internal diameter 21 mm).
• Do not use any hygroscopic materials for the sealing.
> Only use force on the union nut.
Depending on the application, there are three different assembly
options:
Assembly Application
Without stainless steel
measurement chamber
and cooling coil
• Process temperatures 0 to 50 °C
• Attachment of the sensor directly in
the process possible
• No fast assembly/dismantling of the
testo 6781 required and sufficient
inflow of the sensor (1 l/min.) exists
17
4 Transmitter
Assembly Application
With stainless steel
measurement chamber
• Process temperatures 0 to 50 °C
• Fast assembly/dismantling of the
testo 6781 required and/or
• No sufficient inflow of the sensor
(1 l/min.) exists
With stainless steel
• Process temperatures 50 to 200 °C
measurement chamber
and cooling coil
4.3.1.1. Without stainless steel measurement chamber and cooling
coil
CAUTION
Compressed air! Danger of injury!
> De-pressurize pipe sections (e.g. compressor off or use of
bypass) and vent them before opening.
Clamp ring screw connection is already pre-assembled.
Screw connection body (1) and union nut (2) have a pointshaped marking (4).
18
1. Screw thread in process.
2. Turn housing (3) to desired position without much exertion
of energy.
3. Tighten union nut (2) finger-tight.
4. Hold screw connection body (1) with a suitable spanner.
5. Tighten union nut (2) slightly past the marking (4).
An increased resistance can be felt when tightening.
4 Transmitter
6. Close ventilation of the pipe section and pressurize the pipe
section again.
4.3.1.2. With stainless steel measurement chamber (max. 35,000 hPa)
1. Connect measurement chamber without testo 6781 transmitter
to quick-release compressed-air fastener for approx. 10 - 30
sec. to blow out any dirt deposits.
2. Remove measurement chamber from quick-release
compressed-air fastener.
3. Screw process connection (G1/2) of the testo 6781 transmitter
into the thread of the measurement chamber.
4. Mount 6781 as described under Without stainless steel
measurement chamber and cooling coil page 18.
5. Engage quick-release fastening of the measurement chamber
in the standardized socket of the compressed air line.
4.3.1.3. With stainless steel measurement chamber and cooling coil
(max. 35,000 hPa)
1. Connect measurement chamber without testo 6781 transmitter
to quick-release compressed-air fastener for approx. 10 - 30
sec. to blow out any dirt deposits.
2. Remove measurement chamber from quick-release
compressed-air fastener.
3. Screw process connection (G1/2) of the testo 6781 transmitter
into the thread of the measurement chamber.
4. Mount 6781 as described under Without stainless steel
measurement chamber and cooling coil page 18.
5. Engage quick-release fastening of the measurement chamber
in quick-release fastening of the cooling coil.
6. Engage second quick-release fastening of the cooling coil in the
standardized socket of the compressed air line.
19
4 Transmitter
Pos: 37 /TD/Erste Schritte/MUF 63xx/Spannungsversor gung/Analogausgänge anschließen 6781 @ 3\mod_1239 9516 83334_79.doc @ 31673 @ 45
4.3.1.4. Connecting voltage supply and analog outputs
Wiring diagram for 4-wire system (0 to 20 mA/4 to 20 mA/0 to
1 V/0 to 5 V/0 to 10 V)
1-channel
0 to 20 mA/4 to 20 mA
max. load per 500 Ω
0 to 1 V/0 to 5 V/0 to
10 V
Pos: 38 /TD/Erste Schritte/MUF 63xx/Option Stecker verbindung 6781 @ 3\mod_1239951744567_79.doc @ 31694 @ 4
20
Requirement for the connecting cable of the supply:
• Shielded and insulated with cross-section of at least
0.25 mm
2
.
• The supply line must be secured against exceeding 8 A.
• An OFF switch must be installed in an easily accessible
position close by and be marked as such.
4.3.1.5. Plug-in connection for power supply and channel
M12 plug-in connection (5-pin) connector
View of the plug-in connection in the installed state from outside
PIN Assignment
1 -24 V
2 +24 V
3 + Ch1
4 - Ch1
5 PE
Pos: 39 /TD/Überschriften/MUF/1.3.3 Gerät abgleic hen @ 3\mod_1236081099337_79.doc @ 27173 @ 3
4.3.2. Adjusting the instrument
Pos: 40 /TD/Erste Schritte/MUF 63xx/1-Punkt-Abgleic h 6781 @ 3\mod_1239794807174_79.doc @ 31163 @ 44
4.3.2.1. Self-adjustment
Conventional trace humidity sensors show a steep rise in
measuring uncertainty at low humidities. With the trace humidity
sensor of the testo 6781, these measuring uncertainties are
corrected by means of an automatic self-adjustment process. This
means that extremely accurate measuring results are also attained
in the range up to -90 °C
To this end, a temperature sensor which is used as a heater is
fitted on the back of the sensor element. A humidity and
temperature value pair is taken in both the unheated and heated
state. The deviation of the probe obtained from these pairs of
values is automatically corrected.
.
td
4 Transmitter
21
4 Transmitter
• Deactivating the self-adjustment function of the testo
6781 will reduce measuring accuracy and should
therefore be restricted to the shortest possible length of
time.
• During the self-adjustment phase, the analog outputs,
the display value and the output value are "frozen".
Self-adjustment active is shown in the display until it
has finished. The self-adjustment time (incl. heating
time, calculation time, cooling time) is 30 minutes. The
cycle time can be edited in the P2A software, see Selfadjustment page 54.
• At temperature wn > 0 °C, the self-adjustment time
becomes longer.
4.3.2.2. 1-point adjustment by entering a reference value
Using the 1-point adjustment, you can enter a reference value for
one of the working points you have selected (e.g. -40 °C
this, you achieve a minimum target/actual deviation around this
working point.
But the further away the measurement is from the working point,
the greater the deviation can become. The 1-point adjustment
should therefore only be used for a relatively narrow measuring
range (working range)
✓ A reference measuring instrument (e.g. dewpoint mirror
hygrometer) is ready.
1. Expose the reference measuring instrument and testo 6781 to
the same constant conditions and wait for the equalization
period to expire.
The ideal accuracy is reached when at least two adjustment
cycles are run through at dewpoint temperatures above -60
°C
, whereby four adjustment cycles are recommended at
td
dewpoint temperatures below -60 °C
.
td
2. Measure the reference value and compare with the reading of
the testo 6781.
3. In the event of deviations of the values: Enter reference value
• via the user menu (see Enter reference value for 1-point
adjustment page 35) or
• via the P2A software (see 1-point adjustment page 61).
). With
td
22
Loading...