SERIES 36 Xi W (CTD) - keller
High-precision pressure level transmitter
Series 36 Xi W (CTD)
multi-parameter probe with digital interfaces
The 36 Xi W series is built on the latest-generation microcontroller platform, which KELLER has
developed to meet extremely high precision requirements and increase compatibility with a wide
variety of interfaces. Along with pressure (level) information, digital interfaces also transmit other
water parameters such as temperature and conductivity.
RS485
Robust interface with differential gauges, for lines up to 1,4 km in length. Modbus RTU and proprietary KELLER bus protocol
SDI-12 Standard interface for environmental monitoring, ideal for battery operation
The 36 Xi W series is based on the proven KELLER 36 X W series using the high-quality
10 L-series pressure transducer. All series X pressure level transmitters feature an RS485 interface, which provide pressure and temperature standard, while versions requiring higher accuraty, temperature or conductivity sensor are available options. Multi-parameter probes fitted with
pressure, temperature and conductivity sensors (CTD – conductivity, temperature, depth), are
approximately 90 mm longer.
36 Xi W
Pressure sensor: accuracy 0,02 %FS
Temperature sensor: accuracy 0,5 °C or 0,1 °C
36 Xi W CTD
Pressure sensor: Temperature sensor: Conductivity sensor:
accuracy 0,02 %FS
accuracy 0,1 °C
accuracy 2,5% of the selected measuring range 4 ranges:
0,2 / 2 / 20 / 200 mS/cm
Series 36 Xi W
Both versions can be supplied configured for absolute pressure (measured relative to a vacuum
→ PAA) or relative pressure (fitted with capillary tubes for measuring relative to atmospheric
pressure → PR).
Characteristics
Modbus RTU
• Pressure sensor: resolution 5 ppm
• Mathematical compensation of nonlinearities and temperature dependencies
• Sturdy stainless steel housing (titanium or Hastelloy also available)
• Extended lightning protection fitted to the SDI-12 interface as standard
• Level measuring ranges from 0…3 to 0…300 mH2O. Higher ranges are possible using a
SubConn® connector
• Ultra-high long-term stability
SDI-12
Series 36 Xi W CTD
ca. 16
111 ±1
17,5
Electrical connections
36 Xi W
ø22
Function
27
135 ±1
17,5
14
Optional:
36 Xi W with Subconn®
connector
ø22
Wires
+Vcc
Black
GND
White
RS485A
Blue
RS485B
Yellow
optional
36 Xi W CTD
SDI-12
Red
CASE
Cable shield
ø22
17,5
ca. 14,5
223 ±1
KELLER AG für Druckmesstechnik
CH-8404 Winterthur
+41 52 235 25 25
info@keller-druck.com
KELLER Ges. für Druckmesstechnik mbH
D-79798 Jestetten
+49 7745 9214 0
eurocenter@keller-druck.com
Edition 04/2017
Subject to alterations
Companies approved to ISO 9001
www.keller-druck.com
Series 36 Xi W (CTD)
Interfaces
Advanced commands:
Level transmitter
+VCC
GND
RS485A
RS485B
SDI-12
Level transmitter
+VCC
GND
RS485A
RS485B
SDI-12
Power supply
+VCC
GND
RS485 data capture
RS485A
RS485B
GND
SDI-12 data capture
SDI-12
GND
RS485
Modbus RTU / KELLER bus protocol
The extremely robust RS485 interface enables a bus system to be created with up to 128 users and a total line length of up to 1,4 km. The
baud rate of the half-duplex interface can be switched between 9600
and 115’200. The proprietary KELLER bus protocol and the Modbus
RTU protocol are already implemented, allowing the measured values
to be read off and configuration and calibration to be performed. The
free CCS30 software for PC can be used for this.
Measuring channel assignment (up to 4 channels):
P1Pressure
TOB1 Temperature (silicon sensor)
T
Temperature (Pt1000)
ConConductivity
• Adjusting the pressure and temperature unit
• Adjustable zero point and amplification
• Adjustable gravitational constant to increase measuring accuracy
• Programming a user-specific ID
• Configurable continuous measurement with adjustable measuring
interval and communication of up to eight pressure waves
• Switching to RS485
A detailed description of SDI-12 communication can be found on the
KELLER website.
Sensor system
Pressure measurements
The pressure level transmitters are calibrated with pressure in bar. The
measuring and testing equipment used has been calibrated to national
standards.
The RS485 interface always displays pressure in bar. In SDI-12 mode,
it is possible to select the unit in which the pressure value is transmitted. The pressure can be read off as a level (water depth) based on the
following formula:
h = f
p
ρ
g
f
p
ρ
g
Pressure (measured value)
Water density at 3,98 °C (constant of 1000 kg/m3)
Gravitational acceleration (can be configured; default: 9,80665 m/s2)
Factor used in conversion to unit of height (underlying table)
Depending on the design of the pressure level transmitter, pressure
can be recorded relative to a vacuum (PAA models) or to ambient pressure (PR models).
A detailed description of RS485 communication can be found on the
KELLER website.
SDI-12
As well as the standard RS485 interface, which provides access to
all configuration registers, the pressure level transmitter can also be
ordered with an SDI-12 interface. Only one interface will be active at
any one time. Corresponding commands are used to switch between
interfaces (default setting on delivery: SDI-12).
SDI-12 is a tried-and-tested standard for connecting data loggers and
digital sensors in environmental monitoring applications. The SDI12 interface has been optimised for use in battery-operated systems
that employ a data logger and multiple sensors on the same bus. The
interface is underpinned by a standardised, ASCII-based bus protocol.
In SDI-12 mode, the pressure level transmitter is only active when it
is being actuated by the data logger or logging a measurement. At
all other times, the transmitter is in standby mode, requiring very little
current (< 0,1 mA).
Standard commands:
• Reading off measurements with and without checksum
• Changing the sensor address
• Reading off ID
Temperature measurements
Two different temperature sensors are available with varying degrees
of calibration and accuracy. End-of-line calibration is performed on
Pt1000 sensors in a water bath. The temperature information (TOB)
from the silicon sensor is always available and is also used for temperature compensation in the pressure sensor, with which it forms
a single unit. The Pt1000 sensor in the conductivity module is positioned between the electrodes to provide as accurate a medium temperature as possible, which is then used for temperature compensation
of the conductivity.
Conductivity measurements
Conductivity measurements are used in the monitoring of bodies of
water (environment). Thanks to four-wire technology, the conductivity probe is not influenced by polarisation effects or dirt. Methods for
temperature compensation of the conductivity output*:
• Normalization to 25 °C or to 20 °C through linear compensation in the
range of 0 to 8%/K according to DIN/EN27888.
• or normalization to 25 °C through non-linear table
The Conductivity is calibrated via the RS485 interface using the software “ConductivityCalibration Tool”.
The conductivity probe is only switched on in SDI-12 mode when a
conductivity measurement is requested. In RS485 mode, the conductivity probe can be switched on and off to save energy.
* Default configuration is linear compensation with 2,2%/K normalized to 25°C.
Other customised factory setting possible upon demand. Customer can enter new ­
alternative settings any time via software.
KELLER AG für Druckmesstechnik
CH-8404 Winterthur
+41 52 235 25 25
info@keller-druck.com
KELLER Ges. für Druckmesstechnik mbH
D-79798 Jestetten
+49 7745 9214 0
eurocenter@keller-druck.com
Edition 04/2017
Subject to alterations
Companies approved to ISO 9001
www.keller-druck.com
Page 2 of 3
Series 36 Xi W (CTD)
Specifications
Pressure
Electrical data
RS485
SDI-12
Standard ranges in bar 1)
Supply voltage
‧ with extended
lightning protection
3,2…32 VDC
4,5…32 VDC
6…32 VDC
PR (relative pressure)
0,3
1
3
10
30
PAA (absolute pressure) 0,8…2,3 0,8…4 0,8…11 0,8…31 2)
Water column in metres ca.3
10
30
100 300 5)
2)
Overload resistance
max. 300%
Technology
oil-filled, insulated, piezoresistive
pressure transducer in a metallic casing
Resolution
typ. 5 ppm (corresponds to 0,0005 %FS)
Accuracy 3) 5)
± 0,02 %FS max.
(0,3 bar Range: ± 0,04 %FS)
Comp. temp. range
0…50 °C
Total error band
± 0,1 %FS max.
(0,3 bar Range: ± 0,2 %FS)
4) 5)
120, 240 (default), 480 Hz
Long-term stability
ranges > 1 bar: ± 0,1 %FS max.
ranges ≤ 1 bar: ± 1 mbar max.
Degree of dependency
on location
± 1,5 mbar max.
-10…80 °C
Technology
silicon (pressure measuring bridge, TOB6))
optional Pt1000
Resolution
< 0,01 °C
Accuracy
silicon sensor: typ. ± 0,3 °C
Pt1000 sensor: ± 0,1 °C max.
Int. measurement rate
0 µS/cm…200 mS/cm
0,2 / 2* / 20 / 200* mS/cm
Technology
6 platinum electrodes, 4-wire technology
Comp. temp. range
-10…+60 °C
Resolution
< 0,05% of the selected range
Accuracy
< 2,5% of the selected range
Int. measurement rate
1 Hz
• Housing options: Hastelloy and titanium
• Process connection with thread
• Other cable materials (e.g. FEP) available on request
1)
Pressure range buffer: pressures can be measured at up to 10% outside the pressure range either way, in which case “+Inf” or “-Inf”, as appropriate, will be displayed.
5)
Subconn® connectors increase the pressure range to above 30 bar
Pressure ranges > 10 bar are only possible without a conductivity sensor.
6)
3)
Linearity (best straight line), hysteresis and repeatability.
4)
Accuracy and temperature error within the compensated temperature range.
KELLER AG für Druckmesstechnik
CH-8404 Winterthur
+41 52 235 25 25
info@keller-druck.com
<1s
<3s
> 10 MΩ @ 300 V
> 10 mio. pressure cycles
0…100 %FS @ 25 °C
-20…+80 °C
Digital interface
RS485
SDI-12
Communication
protocol
Modbus RTU
KELLER bus
SDI-12 V1.3
Baud rate
9600*, 115’200 bit/s
1200 bit/s
Identification
Class. Group: 5.21
Units of pressure
bar
bar*, mbar, mH2O,
psi, ftWC, inWC
Units of temperature
°C
°C*, °F, K
Unit of conductivity
mS/cm
mS/cm
Dimensions
ø 22 mm, length see drawing
Weight
ca. 170 g excl. cable (CTD ca. 300 g)
Housing material
stainless steel 316L (DIN 1.4435 /
1.4404)
Cable material
PR: polyethylen (PE)
PAA: polyolefin (PE based)
Other materials in contact with media
seals: Viton®, protective cap: POM
conductivity (additional): platinum, PEEK
Standards and protection
Options
2)
< 300 ms
3 s typ., 6 s max.
Mechanical data
Conductivity
Ranges selectable
using software
Start-up time P1, TOB1
P1, T, Con
Storage temperature
12 Hz TOB only 6)
6 Hz Pt1000 without conductivity
1 Hz Pt1000 with conductivity
Measuring range
< 0,1 mA (sleep)
< 5,5 mA (active)
< 13 mA (active)
Endurance
Temperature
Measuring range
< 6 mA (active) 7)
< 14 mA (active) 7)
Insulation GND-CASE
Operating temperature 5) -20…80 °C
Int. measuring rate
(adjustable)
Power consumption
‧ without conductivity
‧ with conductivity
EMC compliance
EN 61000-6-2: 2005
EN 61000-6-3: 2007
EN 61326-2-3: 2006
Reverse polarity and
overvoltage protection
± 32 VDC power supply and RS485
± 24 VDC SDI-12
Standard lightning
protection in accordance with EN 61000-4-5
Line-Line: 50 A @ 8/20 µs
Line-CASE: 200 A @ 8/20 µs
Extended lightning prot.
(standard at SDI-12)
Line-Line: 10 kA @ 8/20 µs
Line-CASE: 2 kA @ 8/20 µs
Degree of protection
IP68
Outside the compensated temperature range up to the limits of the operating temperature range, the deviation will be up to twice the value displayed.
Temperature information for the pressure sensor (TOB: top of bridge)
Power consumption without communication. During the response time (9 ms @ 9600 Baud, 1 ms @ 115’200 Baud), an extra 1…40 mA depending on the line termination.
7)
* Default setting, other defaults on demand. Customer can enter new ­alternative settings any time via software.
KELLER Ges. für Druckmesstechnik mbH
D-79798 Jestetten
+49 7745 9214 0
eurocenter@keller-druck.com
Edition 04/2017
Subject to alterations
Companies approved to ISO 9001
www.keller-druck.com
Page 3 of 3
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