Amplified LVDTs
The amplified LVDTs They integrate within the sensor itself the electronics necessary to excite and condition the inductive element, providing a directly usable analog signal by a PLC, data acquisition system, indicator or compatible controller.
Schreiber Messtechnik has different families of Half-bridge LVDT with integrated electronics, From miniature sensors to long-travel transducers, programmable versions, robust designs, and models specifically for pressure applications. Depending on the part number, outputs such as 0-20 mA, 4-20 mA, 0-10 V or ±10 V.
Quick selection based on the application:
- Miniature and small space: SM34 series, with small diameter body and integrated electronics.
- Threaded mounting: SM30 and SM31 series, with M30 × 1.5 housing.
- Compact square body: SM32 and SM33 series.
- Travel up to 200 mm: SM40 series and SM44 family.
- Travel up to 360 mm: SM41/SM43 and SM42 families.
- Applications under pressure: specific versions such as SM46.
- If you need to separate the electronics from the sensor: consult the Unamplified LVDT.
What does it mean for an LVDT to be amplified?
In an amplified LVDT, the conditioning electronics are integrated into the transducer itself. Movement of the core modifies the inductance distribution of the coil system, and the integrated electronics transform that variation into a electrical signal proportional to the displacement.
The installation scheme is simplified compared to a passive sensor:
LVDT with integrated electronics → analog signal → PLC / data acquisition
It is not necessary to install a separate external LVDT air conditioner as long as the power supply and sensor output signal are compatible with the equipment to which it will connect.
When should you choose an LVDT with integrated electronics?
Integrated electronics are especially practical when the goal is to reduce the number of system components and connect the transducer directly to a compatible analog input.
It can be a good choice when:
- a is desired simple and compact installation;
- The PLC or acquisition system has a compatible 4-20 mA, 0-10 V or ±10 V input;
- There is no need to physically separate the electronics from the point of measurement;
- The aim is to replace one sensor with another with a direct industrial output;
- The sensor must be integrated as an autonomous element within an OEM machine or equipment.
When temperature, available space, or other conditions make it preferable to keep the electronics away from the point of measurement, a Unamplified LVDT.
Outputs 4-20 mA, 0-10 V and ±10 V
The integrated electronics can convert the measured displacement into different analog signals depending on the family and reference.
| Exit | Regular use | Consideration |
|---|---|---|
| 4-20 mA | PLC, automation and industrial transmission. | Suitable for power transmission and industrial wiring. |
| 0-20 mA | Compatible analog current inputs. | The exact input range of the receiving equipment must be checked. |
| 0-10 V | PLC, data acquisition and control. | It is advisable to consider cable length and ground reference. |
| ±10 V | Measurement systems with bipolar signal with respect to the central point. | It requires an input compatible with bipolar voltage. |
Not all models offer all signals. The output, power supply, and connections should always be checked in the technical specifications of the selected model.
Schreiber families with integrated electronics
| Family | Format | Route | Feature |
|---|---|---|---|
| SM263 | Ø12 mm | Up to 200 mm | Integrated electronics in 2-wire technology |
| SM30 / SM31 | M30 × 1.5 | Up to 15 mm | Threaded mounting; SM31 programmable |
| SM32 / SM33 | 25 × 25 mm | Up to 15 mm | Square body; programmable SM33 |
| SM34 | Ø10 mm | Up to 20 mm | Miniature; current and voltage versions |
| SM40 | Ø25 mm | Up to 200 mm | Standard industrial sensor; also used as a probe depending on the version |
| SM41 / SM43 | Ø25 mm | Up to 360 mm | Integrated/programmable electronics |
| SM42 | Ø25 mm | Up to 360 mm | Designed for long journeys |
| SM44 | 30 × 30 mm | Up to 200 mm | Robust stainless steel housing |
| SM46 | Version for pressurized installation | 20 mm in the documented version | Integrated electronics; applications up to 315 bar depending on version |
The exact characteristics of travel, accuracy, power supply, output signal, temperature and protection depend on each reference.
Note: The old SM27 is listed as a model not recommended for new developments, and Schreiber indicates the SM34 as successor.
How to select an amplified LVDT
In addition to the travel and mechanical geometry, the following should be checked specifically in an LVDT with integrated electronics:
- Required output signal: current or voltage.
- Food available.
- PLC input type or acquisition.
- Signal direction: increasing or decreasing when the reference allows it.
- Central point and electric scale.
- Cable length.
- Temperature and degree of protection.
- Required route and linearity.
- Geometry: cylindrical, threaded, square, feeler or other variant.
To decide first between integrated or external electronics, you can consult the general category of LVDT sensors.
Amplified LVDT or unamplified LVDT
The main difference is where the signal conditioning takes place.
- Amplified LVDT: The electronics are integrated into the sensor and directly provide a conditioned analog signal.
- Unamplified LVDT: The sensor element connects to compatible external electronics.
Integrated electronics simplify installation. External electronics, on the other hand, allow the electronic components to be separated from the point of measurement and can offer advantages in certain environmental conditions or OEM integrations.
You can consult the families of Unamplified LVDT Schreiber to compare both configurations.
Amplified LVDT FAQ
Does an amplified LVDT need an external conditioner?
Normally not. The conditioning electronics are built into the transducer itself. Only the power supply and signal compatibility with the receiving equipment need to be checked.
Can it connect directly to a PLC?
Yes, provided the sensor output is compatible with the PLC's analog input. The signal, power supply, polarity, and wiring diagram of the specific part number must be checked.
Are there any Schreiber LVDTs with a 4-20 mA output?
Yes. There are different Schreiber product families and models with current output, including 4-20 mA versions. Availability depends on the model and its electrical configuration.
Are there versions with 0-10V or ±10V output?
Yes. Certain families offer voltage outputs, but the exact reference should be checked because not all models have the same variations.
What is the difference between SM34 and SM40?
The SM34 is designed for compact installations and travel distances up to 20 mm, while the SM40 family features a larger body and reaches travel distances of up to 200 mm. The specific selection also depends on the signal, accuracy, mounting requirements, and environmental conditions.
What data does GUEMISA need to select an amplified LVDT?
Travel distance, available space, mounting type, output signal, available power supply, PLC or data acquisition system input, and environmental conditions. For replacing an existing sensor, it is also helpful to have a reference, photograph, and technical data sheet.
Selection and replacement of LVDTs with integrated electronics
GUEMISA can help select a Schreiber amplified LVDT for machinery, test benches, automation and OEM equipment, taking into account both the mechanical characteristics and the signal that the control system needs to receive.
To consider a replacement, please send us the existing brand and reference, route, dimensions, power supply and output signal. If you have a diagram, photograph, or technical data sheet, we can also compare the assembly and electrical compatibility.
Products: 13