8740, 8741DC/DC displacement sensors

Inductive, robust and precise! Ideal for displacement measurements and the detection of mechanical variables that can be converted into displacements. Vibration and shock-resistant for reliable use in demanding environments. With integrated measuring amplifier and available as a special version on request.

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dc dc wegsensor 8740 mit tastfeder 8741 burster dc dc displacement sensor with spring probe tip dc/dc

Productinformation

Principle	Inductive
Measuring range	8740 0 ... 1 mm 0 ... 2 mm 0 ... 5 mm 0 ... 10 mm 0 ... 25 mm 0 ... 50 mm 0 ... 100 mm 0 ... 150 mm 8741 0 ... 1 mm 0 ... 2 mm 0 ... 5 mm 0 ... 10 mm 0 ... 25 mm 0 ... 50 mm
Signal output	0 ... 10 V 0 ... 5 V ±5 V 4 ... 20 mA 10 ... 0 V 5 ... 0 V
Protection class	8740 IP64 8741 IP40
Range of operating temperature	-20 ... +80 °C
Excitation voltage	9 ... 28 VDC
Electrical connection	8740 3-core, shielded 2 m PVC cable 8741 7-pin connector plug
Return spring	8740 No 8741 Yes
Specific characteristics	8741 Integrated measuring amplifier Optional output 0 ... 5 V, 5 ... 0 V, 10 … 0 V, ±5 V, ±10V, 0 … 20 mA, 4 … 20 mA Optional USB output via 9206 Insensitive to vibration and shock due to encapsulated electronics Special versions available on request

8740_8741
DE EN

8740_8741
DE EN

Inductive displacement sensors based on the differential transformer principle (LVDT) can be used to measure displacements and, indirectly, quantities that can be converted into displacements, such as forces, compressions, strains, torques, vibrations and so on.

These sensors are used in many areas of technology (industry, research, development...) due to their very good measurement quality, high degree of protection and long durability.

Applications include measuring, controlling, regulating and monitoring slow and fast movements between machine parts, position measurements and position changes of components and foundations, servo controllers, valve controls, robot controls, growth measurements and so on.

The design is robust - the coils and electronics inside are moulded so that they can withstand shocks and vibrations without any problems. This also makes these sensors suitable for mobile applications (e.g. in vehicles) and test benches with large numbers of test cycles.

These displacement sensors with integrated electronics contain a differential transformer and a carrier frequency measuring amplifier, which are housed and encapsulated in a stainless steel housing.

The differential transformer consists of a primary and two secondary windings, which are arranged symmetrically to the primary winding. The integrated electronics demodulate, filter and amplify the AC voltage induced in the secondary coils. A rod-shaped core can be moved within the differential transformer.

The sensor supplies a voltage (DC) at the output that is proportional to the displacement, depending on the position of the displaceable core inside the sensor.

The model 8740 contains a core that is axially flexible without spring force and has 2 sliding rings made of Teflon. These are used to centre the core in the through-hole of the sensor body. The M2 thread at the end of the push rod is available for mechanical coupling of the core to the measurement object. Lateral forces on the push rod must be avoided.

The push rod of model 8741 is mounted on ball bearings. The probe tip is compressed against the target by a spring. This design is advantageous when a mechanical coupling is either expensive or impractical. Here, too, lateral forces lead to a shortened durability. The measuring side of the sensor is protected against dirt and splash water by a bellows.

Sensor holder
DE EN
M 24 mounting thread
DE EN
Sensor Winkelhalterung
DE EN
Probe tips
DE EN

High-speed switching outputs
Mathematical function
High sampling rate
Measured values can be transferred via PROFIBUS, RS232, USB or analog output

TASK

The flatness of a workpiece needs to be measured. To do this, measurements must be taken at three points to determine whether the workpiece is within tolerance. The results from these measurement points are compared using an electronic analysis unit. If the workpiece surface is found to be out of tolerance, the unit must immediately indicate the point at which the maxima have been exceeded. In addition, a visual display is required to make it easier to identify such workpieces.

SPECIFIC REQUIREMENT

High sampling rate, high-speed switching of limits.

SOLUTION

burster displacement transducers are used at the three measurement points. All displacement transducers from the burster range are suitable for use here. A SENSORMASTER 9163, with two main inputs, performs the analysis. The unit uses the two mathematical functions "Fin.A" and "Fin.B" to determine the mean values. To do this, the user assigns each of the inputs and the function "Fin.B" to a limit switch. These switches are configured as a direct-switching, symmetric alarm with hysteresis for minimum and maximum values. The process-value display can be configured to show a change in display colour as soon as one of the limit switches is active. In this case, the limit indicators show which measurement value is out of tolerance. Using the RS232 option with the 9163-P100 measurement data software, a PC can be employed to log and archive the measurements. This process can be automated by the controller communication tool included in the software.