Endress+Hauser CPS71D Series Capacitive Level Sensors

Technical Dossier

Product Details And Specifications

Endress+Hauser CPS71D Series: Comprehensive Module Range and Technical Overview

The Endress+Hauser CPS71D series represents a mature, field-proven line of capacitive point level detection sensors deployed across global heavy industry. Installations span petrochemical refineries, nuclear auxiliary systems, offshore platforms, chemical processing plants, and bulk solids handling facilities. The CPS71D operates on the principle of capacitance change detection between an active electrode and a reference electrode (or vessel wall), making it suitable for conductive and non-conductive media alike. Its compact, rod-type construction and process-sealed electronics have made it a standard specification item in DCS-integrated level monitoring loops, particularly in Endress+Hauser Liquipoint and Solicap system architectures. The series is manufactured in Germany and carries SIL qualification for safety-instrumented system (SIS) applications under IEC 61508.

The Evolution of CPS71D Architecture

The CPS71D series succeeded the earlier CPS11 and CPS41 capacitive sensor families, which used discrete analog signal conditioning circuits and required external relay amplifiers (e.g., FTL325, FTL375) for switching output. The CPS71D integrated the signal processing electronics directly into the sensor head, eliminating the need for a separate amplifier unit in most installations. Early CPS71D variants used a 2-wire PNP/NPN transistor output with fixed sensitivity. Subsequent hardware revisions introduced adjustable sensitivity via an external teach-in button, allowing field calibration without process interruption. The D-suffix designation (CPS71D) indicates the current-generation design with integrated diagnostics and IO-Link readiness on select order codes. Compatibility with legacy Endress+Hauser FTL amplifier wiring is maintained through passive adapter cables, preserving backward integration with older DCS marshalling cabinets. The series is now in a mature/sustaining lifecycle phase; Endress+Hauser continues to supply spare units and repair services, but no major architectural revisions are planned. Long-term maintenance sourcing from authorized distributors and certified aftermarket suppliers is the recommended strategy for installed base management.

CPS71D Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly stocked configurations within the CPS71D series. Each order code encodes electrode material, process connection, output type, and approval class. Functional categories are noted per line.

Point Level Detection — Standard Output:

• CPS71D-7TB21: Rod electrode, G¾ thread, PNP NO output, 24 VDC, standard sensitivity, IP67.
• CPS71D-7TB22: Rod electrode, G¾ thread, PNP NC output, 24 VDC, standard sensitivity, IP67.
• CPS71D-7TB31: Rod electrode, G¾ thread, NPN NO output, 24 VDC, standard sensitivity, IP67.
• CPS71D-7TB32: Rod electrode, G¾ thread, NPN NC output, 24 VDC, standard sensitivity, IP67.
• CPS71D-7TA21: Rod electrode, G½ thread, PNP NO output, 24 VDC, compact body, IP67.
• CPS71D-7TA22: Rod electrode, G½ thread, PNP NC output, 24 VDC, compact body, IP67.

Point Level Detection — Extended Electrode / High-Temperature:

• CPS71D-7TC21: Extended rod electrode, G1 thread, PNP NO, rated to 100 °C process temperature, IP67.
• CPS71D-7TC22: Extended rod electrode, G1 thread, PNP NC, rated to 100 °C process temperature, IP67.
• CPS71D-7TD21: Extended rod electrode, G1 thread, PNP NO, high-pressure rated, IP68.
• CPS71D-7TD22: Extended rod electrode, G1 thread, PNP NC, high-pressure rated, IP68.

Point Level Detection — ATEX / Hazardous Area Approvals:

• CPS71D-7TB21-ATEX: G¾ thread, PNP NO, ATEX Zone 1/21 certified, Ex ia IIC T6, 24 VDC.
• CPS71D-7TB22-ATEX: G¾ thread, PNP NC, ATEX Zone 1/21 certified, Ex ia IIC T6, 24 VDC.
• CPS71D-7TC21-ATEX: Extended rod, G1 thread, PNP NO, ATEX Zone 1/21, high-temperature variant.

Point Level Detection — IO-Link / Smart Output:

• CPS71D-7TB21-IOL: G¾ thread, IO-Link 1.1 interface, PNP switching output, process data transmission via IO-Link master, IP67.
• CPS71D-7TC21-IOL: Extended rod, G1 thread, IO-Link 1.1, high-temperature process, IP67.
• CPS71D-7TB21-SIL: G¾ thread, PNP NO, SIL 2 capable per IEC 61508, for use in safety-instrumented functions (SIF).

Sourcing Hard-to-Find & Obsolete CPS71D Parts

DriveKNMS maintains a dedicated inventory program for Endress+Hauser CPS71D series units, including configurations that have been discontinued from standard production runs or are subject to extended lead times through OEM channels. Our sourcing network covers new-old-stock (NOS) units, factory-refurbished sensors with full recalibration documentation, and tested-used units with residual service life certification. For plants operating legacy DCS architectures where a direct CPS71D replacement is required to avoid re-engineering the I/O loop, DriveKNMS provides cross-reference matching to confirm pin-compatible substitutes. All sourced units are supplied with a traceable inspection record. Minimum order quantities are not imposed for MRO procurement. Typical dispatch for in-stock units is 1–3 business days. For project quantities or blanket orders, contact our technical sales team for lead time and pricing commitments.

Quality Control for the CPS71D Range

Each CPS71D unit processed through DriveKNMS undergoes a structured inspection and functional verification protocol specific to capacitive level sensor technology. Inspection steps include: visual examination of the electrode rod for corrosion, mechanical deformation, or coating damage; continuity and insulation resistance testing between the active electrode and the process connection body; functional switching test using a calibrated capacitance load simulator to verify PNP/NPN output switching at the specified sensitivity threshold; output voltage and current draw verification under rated supply voltage (24 VDC ±10%); and IP rating integrity check via pressurized air test on the cable entry and process seal. For ATEX-certified variants, certification label integrity and Ex marking legibility are verified against the original approval documentation. IO-Link variants are tested using a certified IO-Link master to confirm IODD parameter read/write and process data transmission. All test results are logged and supplied with the unit on request.