Digital strain gauge sensor ZET 7111

Digital strain transducer ZET 7111
Digital output CAN 2.0.
Dynamic measurements.

POR (price on request)

Specifications

of the ZET 7111 Digital Strain Gauges

Metrological Data
Measured value	deformation, strain, torque, force
PT electric voltage measuring range	-7 to +7 mV/V
Common-mode voltage range	0 to 4,5 V
Sensitivity threshold (minimal difference between sequentially measured values)	0.0001 mV/V
Absolute measurement error (of the upper range limit)	0.05 %
Relative measurement error (of the measured value)	0.05 %
Additional measurement error (due to temperature measurement)	0.05 %/10°C
Additional measurement error (zero time drift)	0.05 %/10 min
Parameters diagnostics	feed control, data quality control, bridge or half-bridge integrity control, measuring unit calibration
Technical Specifications
Type of connected primary transducers (PT)	force gauge, bridge or half-bridge strain gauges (strain resistors)
Variable voltage fed to the PT	3 ± 0.5 V
Frequency	1250 ± 10 Hz
Maximal current fed to the PT	10 ± 1.5 mA
Data refresh rate	50, 250, 625, 1,250 Hz
Data interface	CAN 2.0
Transmission rate	100, 300, 1000 kbps
Performance Specifications
Dimensions	71×39×17 mm
Weight (kg)	30 gr
Power supply	9 to 24 V
Consumed power (w/o PT)	0.5 W
Reverse polarity protection	Yes
Operational temperature range	-40 to +100 °C
Electromagnetic Compatibility
IEC 61000-4-2, ESD	contact 4 kV, air 8 kV
IEC 61000-4-4, EFT	power supply 0.5 kV, signal 0.25 kV
IEC 61000-4-5, Surge	500 V

Calculation Method
The input data are converted to the resulting value either in a linear fashion with the slope determined as the transmission ratio, or in a piecewise linear fashion, according to the calibration table.
Synchronization
Interface converter synchronizes the digital sensors. This allows to observe the interaction in different points (locations of the digital sensors) of the facility, and to build diagrams. Synchronization accuracy at CAN transmission rate of 1,000 kbps is ± 1 µs.
Hardware Versions
Standard: laboratory design in a plastic cover (green)
OEM: board covered with a sealing compound.
Heavy Duty*: depending on the task specifics, this may be a version in a heavy duty cover (black) or location of the standard-design unit in an air-tight cover (with a transparent lid).
Ex-proof*: in a heavy duty cover with the explosion protection system of 0ExiaIICT6 X type.
*The cost is calculated individually.

Advantages

of the ZET 7111 Digital Strain Gauges

No adjustment is needed

The characteristics are stored in the measuring unit memory

Measurement results

Measurement results are transmitted in a digital form

Primary transducers: power supply

The primary transducers are powered by the measurement module

Reliability

Stable characteristics and high reliability in operation

Purpose

of the ZET 7111 Digital Strain Gauges

The ZET 7111 module is intended for measuring the relative deformation using primary transducers based on tension gauges. These may be either assembled tension gauges (force gauges, torque gauges), or separate external tension gauges connected using half-bridge or bridge scheme.

Load sensor is powered by AC voltage, so ZET 7111 is used for dynamic measurements.

Operation Principle

of the ZET 7111 Digital Strain Gauges

The digital strain gauge consists of a primary transducer (strain gauge or strain bridge) and ZET 7111 measuring module.

The strain gauge must be installed at the measurement location with the measuring unit installed as close as possible.

The output voltage of the strain gauge is generated in proportion to the action of the measured variable. The measuring unit converts this voltage into the magnitude of the measured variable and transmits the results in a digital form.

Thus, no sensor setting or results processing is required for measuring: all necessary settings are stored in the ZET 7111 unit memory and measurements are performed by the signal processor

which is a part of ZET 7111.

The primary transducer is selected depending on the task to be solved. ZET 7111 digital strain gauges with basic settings measure the magnitude of the relative deformation (when strain bridges are used) or the magnitude of impact forces (when a strain gauge is used). It is possible to configure the gauge to measure different values, for instance: strain, torque, pressure, or weight.

Application Scope

of the ZET 7111 Digital Strain Gauges

Weighing Equipment
The digital load sensors are used in platform conveyor truck, railroad car, crane, hopper, tanker scales, in dosing units
Testing Equipment
Machines for testing materials for tension, testing machines for determining materials compression strength, tensile testing machines, forging presses, preforming units, crush tests

Control Equipment
Systems for pressure monitoring in rolling mills, systems for press-fitting monitoring, pressure plate pressure control systems
Measuring Equipment
For measurements in civil construction when controlling loads in tunnel supports, ground pressures in support walls, etc., for measuring wire and rolls tension, for measuring forces at shock stresses

Directive 2011/65/EU (ROHS, ROHS II)

DIGITAL STRAIN TRANSDUCERS MEET THE REQUIREMENTS OF DIRECTIVE 2011/65/EU (ROHS, ROHS II) CONCERNING LIMITATION TO USE HAZARD SUBSTANCES (PB, HG, CD, CR(VI)) IN ELECTRICAL AND ELECTRONIC EQUIPMENT; THEY ARE MANUFACTURED USING LEAD-FREE METHOD, IN COMPLIANCE WITH THE EUROPEAN COMMUNITY REQUIREMENTS

Rules For Using In Explosion-Hazard Areas

for ZET 7111 Digital Strain Gauges

When using digital gauges in explosion-hazard areas, it is necessary to observe requirements of applicable national standards.

Installation in explosion-hazard areas is allowed for digital gauges intended for use in explosion-hazard areas and bearing the relevant marking: 0ExiaIICT6 X.

For the communication via data transmission channels and electric circuits, the circuits of digital gauges installed in explosion-hazard areas shall be connected to interface converters and power supply sources through intrinsic safety barriers located in explosion-safe areas. A typical connection diagram for digital gauges installed in explosion-hazard zones is shown on the figure, and the recommended types of intrinsically safe barriers are listed in the table below.

Note

The typical diagram on the figure shows names of circuits for RS-485 interface; when designing CAN interface connection diagrams, the names of the circuits shall be replaced as follows: “DATA-” to “H” and “DATA+” to “L”.

Connection Diagrams

of the ZET 7111 Digital Strain Gauges

The digital gauges can be used for building distributed measurement networks. The interface converters must be used for connecting the measurement network to ZETLAB and ZETVIEW systems. Connection via USB (ZET 7174), Ethernet/Wi-Fi (7176), GSM (ZET 7177), and radio channel (units ZET 7172M and ZET 7172S) is available as well. The number of gauges connected to ZET 7174 shall not exceed 4.

Construction-of-a-measuring-network-based-on

ZETLAB software enables connection of up to 200 digital gauges to a single computer. Measurement networks can also be connected to any system via CAN 2.0 interface.

Specialized calculator

for calculating the required type of cables in the construction of measuring lines

Diagram of connection to a measurement line

Scheme-of-connection-to-the-measuring-line

Connection of strain measuring circuits

Control

of the ZET 7111 Digital Strain Gauges

All required settings are stored in memory of the ZET 7111 measuring unit at factory. When independent setting of a digital gauge is required, for instance, in case of replacement of a primary transducer, connect the unit to a computer via the interface converter and launch Device Manager.

Configuring measurement unit

The "Setting" tab

This tab is used for setting the measurement channel.

Settings tab

Parameter	Changeability	Acceptable values	Description
Circuit	Yes	Bridge Half-bridge	Set “Half-bridge” for ZET 7×10 DS and ZET 7×10 DT digital gauges, and set the value for ZET 7×10 depending on the variant of the connection circuit of the external primary transducer
Frequency (Hz)	Yes	50 250 625 1250	Sampling rate is a rate at which the digital gauge will register data
Calculation method	Yes	Transmission ratio Calibration curve	Set the “Transmission ratio” parameter when the linear response of the primary transducer used in combination with the digital gauge is known. Set the “Calibration curve” parameter when the linear response of the primary transducer is not known but it is possible to perform its point calibration for the required measurement range.
Accuracy (%)	Yes	–	This parameter sets the measurement accuracy in per cent. Set the value in accordance with the technical specifications of the primary transducers used in combination with the ZET 7×10 and ZET 7111 digital gauges.
Unit	Yes	mV/V N kg t N/m kN/m MPa GPa etc.	The specified measurement units for identification of physical units in which the variable is measured. They are not used by the digital gauge for any conversions, however, it should be noted that when calculating Sp the parameter values shall be used in the relevant measurement units.
Gauge serial number	Yes	–	Set this parameter only in case of a requirement for identifying the serial number of the gauge connected to digital gauges of ZET 7×10 and ZET 7111 series.

The "Gauge" tab

The “Gauge” tab indicates parameters of the connected tension or force gauge.

Sensor tab

Parameter	Changeability	Acceptable values	Description
Activity status	Yes	Off On	When an external primary transducer (gauge) is connected to digital gauges of ZET 7×10 or ZET 7111 series, select “on”.
Measurement range (in units)	Yes	–	This parameter defines the maximum range of the gauge measurement values. The parameter is indicated in the gauge certificate.
Sensitivity (Sd)	Yes	–	The parameter defines the sensitivity of the external gauge. The parameter is indicated in the gauge certificate.

The "Tension Resistor" tab

The “Tension resistor” tab indicates sensing element parameters when bridge and half-bridge circuits are used.

Tab Strain gage

Parameter	Changeability	Acceptable values	Description
Activity status	Yes	Off On	When external tension resistors are connected to digital gauges of the ZET 7×10 or ZET 7111 series, select “on”.
Sensitivity (Sr)	Yes	Depends on the circuit and selected measurement units	The parameter defines the sensibility of a digital gauge considering the used circuit and measurement unit. The Sr value set for this parameter is calculated using formulas provided in Appendices B and C of the configuration manual.

The "Calibration" tab

The “Calibration” tab is used for calibration of the digital gauge (measurement unit completed with a primary transducer).

Calibration Tab

The tab contains 10 points for calibration of the digital gauge within its measurement range.

The calibration is needed only when the characteristics of the digital gauge (equipped with an in-built or external primary transducer) is unknown, but there exists a possibility to ensure a known load (or travel) impact within the whole measurement range.

The figure above shows an example of three-point calibration of the ZET 7110 DT series gauge for operation in ±0.7 mm range. For calibration, the digital gauge was fixed on M4 mounting screws.

“Direct current voltage meter” software indicator in the “Measurement” menu on ZETLAB software pane defines the measured values for each of the three points of the ZET 7110 DT digital gauge compression degree.

The reference value of 0.7 mm (point 3 in the calibration table) corresponds to the minimum degree of compression of the digital gauge sensing element and equals to the start of reaction to the compression of the digital gauge with compression screws.

The reference value of 0 mm (point 2 in the calibration table) corresponds to the medium compression degree and is determined by the magnitude set by turning the 0.7 mm thread pitch mounting screw 1 turn clockwise (0.7 mm *1 = 0.7 mm).

The reference value of -0.7 mm (point 1 in the calibration table) corresponds to the maximum compression degree and is determined by the magnitude set by turning the 0.7 mm thread pitch mounting screw 2 turns clockwise.

After calibration, press the “Save” button and then set the “Calibration curve” value of “Calculation method” on the “Settings” tab and set the “mm” value for “Measurement unit”, and save all the changes.

The "Displacement" tab

The “Displacement” tab sets the displacement in the initial measurement point.

The Offset tab 7111

Parameter	Changeability	Acceptable values	Description
Displacement	Yes	Off On	Turning the set displacement value on/off.
Displacement in unit	Yes	–	This parameter sets the value necessary to be set as a current indication of the digital gauge.

Example No 1: it is known that a structure element was exposed to 500 MPa strain by the moment of the digital gauge installation, to account for the pre-loaded state of the structure element. Enter the “500” value in the “Displacement for” field, select “On” in the “Displacement” field, and then activate “Save” field; the digital gauge will start registering changes of the controlled structure element strain taking into account the 500 MPa stress.

Example No 2: after installation of tension resistors, the controlled structure element is in a position relative to which its deformation shall be measured. Enter the“0” value in the “Displacement for” field, select “On” in the “Displacement” field, and then activate “Save” field; the digital gauge will start registering the controlled structure element deformation relative to the set zero value.

Basic configuration

of digital strain-gauge sensors ZET 7111

Laboratory version

Strain gauge sensor basic configuration includes:

digital sensor ZET 7111;
DIN-rail mounting panel for plastic modules 71×39;
set of operational documentation.

Industrial version

Basic delivery scope includes:

digital sensor ZET 7111 in industrial casing;
plug for the cable FQ14-4TJ-7 (2 pcs.);
spring nozzle for 7 mm connection (2 pcs.);
connection for the cable FQ14-7TJ-8;
spring nozzle for 8 mm connection;
set of operational documentation.

POR (price on request)

Data protection notification

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Necessary measuring equipment

supplied upon special order

ZET 7174
USB connection

ZET 7176
Ethernet connection

ZET 7173
Offline mode

ZET 7177
GSM network connection

Digital strain gauge sensor ZET 7111

Specifications

Calculation Method

Synchronization

Hardware Versions

Advantages

No adjustment is needed

Measurement results

Primary transducers: power supply

Reliability

Purpose

Operation Principle

Application Scope

Weighing Equipment

Testing Equipment

Control Equipment

Measuring Equipment

Rules For Using In Explosion-Hazard Areas

Note

Connection Diagrams

Specialized calculator

Diagram of connection to a measurement line

Connection of strain measuring circuits

Control

Configuring measurement unit

Basic configuration

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Data protection notification

Necessary measuring equipment

ZETLAB

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