Understanding IP Ratings for LVDT Linear Position SensorsApril 14, 2016
IP (ingress protection) ratings classify the level that a sensor is protected against infiltration by foreign materials such as dust and water. The first digit of the IP rating indicates the protection level against solids entering a sensor while the second one notes moisture resistance (see Table 1). While a zero designates no protection at all, higher numbers identify more stringent defense against elements invading a sensor while operating in a specific environment.
LVDT Linear Position Sensors are typically rated between IP-61 - 69. While dust tight in virtually all configurations (hence the constant use of the number “6” as the first digit of the IP rating) LVDT sensors have different levels of water ingress protection based on construction. For example, some LVDT Position Sensors are built with limited coil protection, while others are protected with varnish or epoxies. Hermetically-sealed LVDTs are welded closed so nothing can intrude the sensor. Each type of LVDT construction bears a different IP rating and may vary by manufacturer. Below are IP ratings for LVDTs offered by TE Connectivity.
I. Non-Hermetically Sealed LVDTs (IP 61 rating)
The external sealing of non-hermetically sealed LVDT linear position sensors from TE Connectivity meets IEC standard IP-61. As these sensors are protected from dust ingress and condensation, they are suitable for the following applications:
• Dry environments with limited dust/dirt exposure
• Laboratory testing, indoor applications
- Precision gaging
- Dial Indicator Replacement
- Robot actuator position feedback
When coils are completely encapsulated in epoxy, the non-hermetically sealed LVDT position sensors increase their rating to IP-64, making them suitable for use in environments where heavy humidity may occur.
II. Hermetically-Sealed LVDTs (IP 68 rating)
Constructed entirely of stainless steel, TE Connectivity Hermetically-sealed LVDT Position Sensors incorporate coil windings that are sealed against hostile environments to IEC standard IP-68. In addition to being protected from total dust ingress, these sensors are rated for long-term water immersion up to a specified pressure without water ingress.
Recommended applications for IP-68 rated LVDTs include:
• Outdoor structural monitoring
• Applications with dust, dirt, grease, humidity
• Heavy industrial
• Valve position
All sensors rated by manufacturers to achieve IP-68 may not be the same but must exceed IP-67 ratings. IP-68 sensors from TE Connectivity are sealed via welding, with all wetted parts constructed of metal with the exception of the connector. The sensors themselves can be submerged in water or other fluids up to 1,000 psi when not operational. However, they cannot operate while submerged because water could intrude into the mating plug and cause a short.
III. Submersible LVDTs (IP 68)
Submersible LVDTs from TE Connectivity are rated at IP-68 with appropriate Seacon-Branter mating connector. The connector and mating plug are rated for pressures up to 5,000 psi or higher. Typically, these units are designed with a 20-year life for use in critical applications where access to the unit for replacement or repair is very costly.
• Seawater or fresh water
• Dam/bridge structural monitoring
• Choke/Christmas tree valve position monitoring
• Subsea extensometers
• Mooring Cables
• ROV actuator/latch position feedback
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