OVERVIEW
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The TE Connectivity Macro Sensors GHSAR 750 Series of 3/4 inch (19 mm) diameter AC-operated LVDTs are designed for a wide range of position measurement applications. These rugged hermetically sealed sensors are constructed entirely of stainless steel, and are intended for general industrial use. The coil windings are sealed against hostile environments to IEC standard IP-68 and input/output connections are made through a sealed axial (GHSA) or radial (GHSAR) connector. The radial connector offers two important benefits. First, it results in a through-bore design, which allows for air purging of the sensor's bearings to remove potential contaminants. The second advantage is shorter installed length compared to units of the same range with axial connectors. The mating connector plug is supplied with the unit.
The sensor consists of a spring loaded shaft running in a precision sleeve bearing and connected to the core of an LVDT. The use of a precision sleeve bearing results in measurement repeatability of 0.000025 inches (0.6 micron) or better. The output from the LVDT can be connected to any standard LVDT signal conditioner and then passed to a gaging column display, digital readout, or computer based data acquisition system.
The probe shaft is fully extended by a spring exerting a nominal force of 6 to 20 ounces depending upon total range. The contact tip supplied is an AGD standard number 9 made from black oxide hardened tool steel. It is fully interchangeable with other 4-48-threaded AGD contact tips.
TE Connectivity Macro Sensors also offers an air-extend/spring-retract version of the radial model. The GHSAR 750-A is designed for a wide range of cycled position measurement and automated dimensional gaging applications where it is necessary or desirable to move the probe out of the way between readings. The shaft is extended by introduction of a low-pressure (10-30 psi), clean, dry air supply, with a regulated flow, through a 1/4 inch barbed fitting on the end of the unit. With the release of pressure, an internal spring returns the probe to its normal position.
Available in ranges of ±0.050 inch (±1.25 mm) to ±2.00 inches (±50.0 mm), the maximum linearity error for a GHSA or GHSAR Series sensor is ±0.25% of full range output using a statistically best-fit straight line derived by the least squares method.
For simplified mounting the GHSA and GHSAR 750 Series have a 1/2-20 UNF-2A thread on the front of the housing, permitting the user to install the LVDT in a mating threaded part or by using the two hex nuts furnished with the sensor. This results in a ready-to-use package for position measurements and longer range gaging applications.
All GHSA/GHSAR Series LVDTs will operate properly with any conventional differential input LVDT signal conditioners, but operation with ratiometric LVDT signal conditioning is not recommended. Macro Sensors offers a full line of LVDT signal conditioners that will deliver optimum performance from any GHSA/GHSAR Series LVDT.
Part Numbers
GHSAR-750-050-A
GHSAR-750-125-A
GHSAR-750-250-A
GHSAR-750-500-A
GHSAR-750-1000-A
GHSAR-750-2000-A
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Air-Extend / Spring-Retract Linear Position Sensor for Industrial Gauging and Automated Measurement
Product Overview
The GHSAR-750-TE AC LVDT from Macro Sensors, distributed by Harold G. Schaevitz Industries (HGSI), is a hermetically sealed, air-actuated linear position sensor designed for cycled measurement and automated dimensional gaging applications. This Linear Variable Differential Transformer combines proven non-contact electromagnetic sensing with controlled pneumatic actuation, making it well suited for applications where the probe must be extended only during measurement and retracted between cycles.
The GHSAR-750 Series is available in measurement ranges from ±0.050 inches up to ±2.00 inches, providing flexibility for both precision gaging and longer displacement measurement applications.
This combination of durability, flexibility, and precision makes the sensor an excellent choice for automated systems where both measurement accuracy and mechanical reliability are critical.
Air-Extend / Spring-Retract Operation
The GHSAR-750-TE features an air-extend, spring-retract mechanism that allows precise control of probe engagement with the measured surface.
Low-pressure air (10–30 psi) extends the probe into position
When air pressure is removed, an internal spring returns the probe to its retracted position
This controlled actuation provides several advantages in real-world applications:
The probe can be withdrawn between measurement cycles to avoid interference with moving parts
Reduced exposure to contaminants, heat, or debris during non-measurement periods
Improved sensor longevity in repetitive or high-cycle environments
Additionally, the through-bore design enables air purging of the internal bearing area. This feature helps remove contaminants and maintain smooth operation over time, particularly in environments where dust, particles, or process residue may be present.
AC LVDT Technology
The GHSAR-750-TE operates as a traditional AC LVDT, meaning it requires an external signal conditioner to function. The sensor itself contains only passive electromagnetic components, with no internal electronics.
Typical operating characteristics include:
Excitation voltage: 3.0 Vrms nominal
Excitation frequency: 2.5 to 3.0 kHz
When energized, the primary winding generates a magnetic field that induces voltages in two secondary windings. The difference between these secondary signals varies with core position, producing an output that is proportional to displacement.
A signal conditioner processes this AC signal, extracting both magnitude and direction of motion to generate a usable DC output.
Advantages of AC LVDT Architecture
The AC LVDT design offers several advantages over sensors with integrated electronics:
No temperature-sensitive electronics inside the sensor
Ability to locate signal conditioning in a protected environment
Greater flexibility in configuring output signals and system gain
Improved long-term reliability in harsh industrial environments
Because the sensing element is purely electromagnetic, the sensor can tolerate conditions that might damage electronic components in other sensor types.
Non-Contact Measurement Principle
The GHSAR-750-TE uses a non-contact measurement principle, meaning there is no electrical contact between the moving core and the sensing elements.
This provides several benefits:
No wear mechanisms that degrade signal quality
Consistent performance over millions of cycles
Minimal maintenance requirements
High reliability in continuous-use applications
The core is guided within a precision sleeve bearing, ensuring smooth motion while maintaining the non-contact sensing advantage of the LVDT design.
Accuracy and Repeatability
The GHSAR-750-TE is designed to deliver highly consistent measurement performance:
Linearity: ≤ ±0.25% of full range output
Repeatability: < ±0.01% of full range output
Repeatability is especially important in automated systems, where the ability to produce consistent readings over repeated cycles directly impacts process control and quality assurance.
The combination of high repeatability and non-contact operation ensures stable performance over time, even in high-cycle environments.
Hermetically Sealed Construction
The sensor features a fully stainless steel construction with hermetically sealed coil windings:
Coil sealing to IEC IP68 standard
Sealed housing and connector interface
This construction provides protection against:
Moisture and humidity
Dust and particulate contamination
Industrial process environments
The hermetic sealing ensures that internal components remain isolated from external conditions, helping maintain measurement stability and extending sensor life.
Flexible Mounting and Integration
The GHSAR-750-TE is designed for easy mechanical integration:
1/2-20 UNF threaded mounting
Supplied hex nuts for secure positioning
Compact 3/4-inch diameter body
Electrical termination is provided through a sealed radial connector, which reduces overall installed length and simplifies routing in tight installations.
This mounting flexibility makes the sensor suitable for both OEM designs and retrofit applications.
Interchangeable Contact Tip
The sensor is supplied with an AGD standard No. 9 contact tip made from hardened tool steel.
Fully interchangeable with other AGD-style tips
Allows adaptation to different measurement surfaces and geometries
This feature provides added versatility for users working across multiple applications.
Signal Conditioning and Output Options
Because the GHSAR-750-TE is an AC LVDT, it requires an external signal conditioner to convert the AC output into a usable signal.
Common output formats include:
±10 VDC for bidirectional measurement
0–10 VDC for unidirectional systems
4–20 mA current loop for long-distance or noise-prone environments
The ability to choose different output types allows the sensor to be integrated into a wide range of industrial control and data acquisition systems.
Typical Applications
The GHSAR-750-TE is particularly well suited for:
Automated dimensional gaging systems
Cycled measurement processes
Industrial inspection equipment
Fabricated metal product measurement
Shaft runout (TIR) measurement
Its ability to retract between measurements makes it especially useful in applications where continuous probe contact would be undesirable or could lead to damage.
Summary
The GHSAR-750-TE AC LVDT provides a reliable and flexible solution for industrial position measurement and automated gaging. By combining air-actuated operation, hermetically sealed construction, and non-contact sensing technology, it delivers accurate and repeatable measurements in demanding environments.