Gems XT-1000 Mode d’emploi
Technical Documentation
Edition: 11-2010
Version: 1
Article no.: 233571
Gems Sensors & Controls One Cowles Rd Plainville CT Telephone 800-378-1600
XT-1000
The magnetostrictive level sensor
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Table of contents
1Properties.........................................................................................................4
2Safety instructions...........................................................................................5
3Design and mode of operation ......................................................................6
4Installation .......................................................................................................8
4.1 Installation with screw-in unit.........................................................................................9
4.2 Installation with flange.................................................................................................10
4.3 Installation on the bypass .............................................................................................10
5Electrical connection......................................................................................12
6User configuration.........................................................................................14
6.1 Measuring span at the level sensor...............................................................................14
6.2 Current consumption in failure mode...........................................................................16
7Technical data ................................................................................................17
7.1 Sensor..........................................................................................................................17
7.2 Floats ...........................................................................................................................19
© Copyright:
Reproduction and translation only with the written consent of GEMS Sensors & Controls.
GEMS Sensors & Controls reserves the right to carry out product alterations without prior notice.
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1Properties
The high-precision and robust XT-1000 level sensor is designed to provide continuous
gauging of liquid media levels in tanks. The measuring principle used by the sensor
exploits the physical effect of magnetostriction and is largely unaffected by temperature.
Magnetostriction is particularly ideal where level measurements are required to be
extremely accurate, e.g. in the chemical industry.
The level sensor outputs measuring signals in the range 4 to 20 mA. Available in lengths
of 8” to 19’ it is compatible with a variety of tank dimensions. It also comes in the
following versions:
Version for installation on a bypass with magnetic float
Version with flange
Version with screw-in unit for infinitely variable positioning of the level sensor
The Ex-approved version of the level sensor can be installed in potentially explosive
atmospheres in which electrical equipment of category 1 (zone 0) or category 1/2
(zone 0/1) are required.
Operating on the digital HART protocol, the XT-1000 HART level sensor is able to output
the position of the first, second or both floats (refer to the XT-1000 HART documenta-
tion).
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2Safety instructions
The purpose of the XT-1000 level sensor is to gauge liquid levels in tanks. Use the level
sensor for this purpose only. The manufacturer accepts no liability for any form of
damage resulting from improper use!
The level sensor has been developed, manufactured and tested in accordance with state-
of-the-art technology and with recognized safety rules and regulations. Nevertheless,
hazards may arise from its use. For this reason, the following safety information must be
observed:
Do not change or modify the level sensor or add any equipment without the prior
consent of the manufacturer.
The installation, operation and maintenance of the level sensor must be carried out only
by expert, authorized personnel. Specialized knowledge must be obtained by undergoing
regular training.
Operators, installers and service technicians must comply with all applicable safety
regulations. This also applies to any local safety regulations and accident prevention
regulations which are not stated in these operating instructions.
The safety instructions in this manual are labelled as follows:
Failure to observe these safety instructions will result in a risk of
an accident or of damage to the XT-1000 level sensor.
Useful information designed to ensure continued and correct operation
of the XT-1000 level sensor or helpful advice to make your work easier.
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3Design and mode of operation
The design of the XT-1000 level sensor has been illustrated using the version with screw-
in unit (see Figure 1).
Inside sensor head (1) of the level sensor, concealed by cap (2), are the protected terminal
clamps and configuration buttons. The electrical connection is established by an
M16 x 1.5 screwed cable gland (3) or M12 plug-in connection at the top of the sensor
head and by ground connector (4) at the bottom of the sensor head (see “Installation”
and “User configuration”).
Probe tube (5) features a screw-in unit (6) (cutting ring or sealing gland coupling) for
height adjustment capability or a flange (not shown) for fixed installation. Float (7) is the
key component for continuous gauging of the product filling level or boundary layer and
is held on the probe tube by a collar (8).
The XT-1000 B version is supplied without a process connection and float.
Figure 1: XT-1000 level sensor
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The measuring principle illustrated in Figure 2 exploits the physical effect of magnetostric-
tion and is largely unaffected by temperature. The probe tube contains a tensioned wire
(1) made of magnetostrictive material. The sensor electronics transmit current pulses (2)
through the wire, which generate a circular magnetic field (3). A magnet (4) contained in
the float acts as the level sensor. Its magnetic field applies an axial magnetic field to the
wire. The superposition of the two magnetic fields produces a torsional wave (5) at the
float position, which then propagates along the wire in both directions. One wave
propagates directly to the sensor head, the other propagates down to the bottom of the
probe tube and is reflected. The time between the current pulse being transmitted and
the wave arriving at the sensor head is measured. From these propagation times, it is
possible to determine the current position of the float.
Figure 2: operating principle of the XT-1000 level sensor
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4Installation
This product should not be installed in a potentially explosive
application.
Also observe any local safety regulations and accident prevention
regulations which are not stated in these operating instructions.
This section describes how to install the level sensor. The procedures for each version are
described separately (see Figure 3).
Figure 3: XT-1000 versions
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During installation, take great care not to bend the probe tube,
and protect the float from shock and impact loads.
Installing a level sensor in areas exposed to a powerful external magnetic
field is not recommended because this could impair gauging.
The level sensor can also be fitted into the tank from underneath.
If the float is removed during installation, it must be slid back onto the
probe tube afterwards with the “TOP” marking oriented towards the
sensor head end, to enable correct measurements to be made.
4.1 Installation with screw-in unit
Figure 4: installation with screw-in unit
Removal of the float is necessary only if the float does not fit through the
installation opening in the tank. Otherwise, please proceed directly to
steps 3, 6 and, if applicable, 7.
Insert the level sensor into the tank (see Figure 4):
(1) Loosen both set screws, remove collar (1) and remove float (2) from probe tube (3).
(2) If necessary, slot screw-in unit (4) onto the probe tube.
(3) Insert the level sensor into the tank, provide screw-in unit thread (4) with a suitable
sealing material, screw it in and tighten.
(4) Slide float (2) back onto probe tube (3).
1
2
3
4
5
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For correct gauging, the float must be slid onto the probe tube with the
“TOP” marking oriented towards the sensor head end, to enable correct
measurements to be made.
(5) Refit collar (1) to hold float (2) on the tube, align the set screws with the groove
and tighten.
(6) Adjust the height of the process connection and secure it in position by tightening
union nut (5).
(7) If applicable, tighten the lock screw (not shown) on union nut (5).
In the case of installation with a cutting ring coupling, it is no longer
possible to alter the position of the level sensor after the union nut has
been tightened. In this event, it would be necessary to return the level
sensor to the factory to have the probe tube replaced.
4.2 Installation with flange
The probe tube is permanently welded to the flange, which means that the installation
length cannot be altered.
Secure the flange using the flange screws.
If the float does not fit through the installation opening, refer to the related installation
instructions in section 4.1.
4.3 Installation on the bypass
The level sensor is installed on the bypass tube using suitable fasteners (nonmagnetic).
To ensure reliable gauging, the probe tube must be fitted with no
deformation on the outside.
The distance between the probe and bypass tubes must be as small as
possible.
Only floats approved by GEMS Sensors & Contr0ls can be used.
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