Do industrial sensors measure up?

It seems that industrial sensors are still awaiting innovation. Senior Tech Editor Rich Merritt reports on who's dominating the sensor business in this Product Roundup of new sensing devices.

By Rich Merritt, Senior Technical Editor

HISTORICALLY, companies in the sensor business made a nice living by specializing in one or more areas, and producing a quality product for the money. For example, few were as successful as the Rosemount DP flow meter, which became the world standard, but many sensor brands and companies became household words. A glance at the CONTROL DESIGN Readers’ Choice Awards will show you the same companies dominating the sensor business with the same products, year after year.

Many of the better-known product and vendor names have been absorbed by acquisitions and mergers, but smart buyer companies keep the old names and keep the products current and competitive, so the same products continue to dominate.

Things are changing, however. Innovation is dying off, as companies try to survive in these tough economic times by competing on price. As a Frost & Sullivan ( study on industrial sensors puts it, “With the majority of offerings being similar, price emerges as the chief driving factor. To compete almost exclusively on the basis of price, manufacturers have been compelled to concentrate on reducing costs.” That means cost cutting is in, R&D is out, and products no longer stay current and competitive.

Innovation would imply the adoption of new technologies, such as smart sensor capabilities, wireless sensors, nanotechnology, plug-and-play (IEEE 1451.4) sensors, and so on, but they don’t seem to be coming to market. We do see plenty of sensors that are getting smarter, as you will see in the roundup below. 

The roundup has sensors that can be remotely calibrated, have many user-selectable features, tune themselves, adjust their own power requirements, and are immune to industrial hazards. These advances are mostly enhancements to existing products, and often don’t add to the basic cost of the sensor. One such sensor, in fact, costs 10% less than the product it is replacing.

But these are not necessarily “smart sensors,” nor do they embody the use of new technologies. The vendors are staying current and competitive with existing technology, but innovation goes out the window. 

The definition of smart sensor varies from vendor to vendor. Some think they are IEEE 1451.4 sensors, others think they are anything with a communications link. According to Frost & Sullivan, a true “smart sensor” has many digital components, including microprocessors, a web server, communications ports, memory, digital outputs, and so on, and is typically priced almost twice as high as the equivalent analog sensor. “The cost of installation is extremely high,” F&S says, “especially in the case of in-plant installation.” 

The true smart sensor would be a device that does more than current products, costs less, and is easy for a machine builder to install. We can’t wait for such sensors. Meanwhile, browse through our selection of new sensor products and you’ll see that some companies are on the right track, whether they have smart sensors or not. 

Product Roundup of Sensor Devices

Take the Cable and Go Home
To help prevent unauthorized changes, the Telemecanique XUN “teachable” photoelectric sensor has a removable push button cable. The cable is used to program the sensor to operate in any of four sensing modes--background suppression, proximity diffuse, polarized retro-reflective and thru-beam. The sensing range of the sensor is 4.7 in. to 49.2 ft, depending on mode and can be panel-mounted or 18 mm thread-mounted. Schneider Electric; 704/916-6173;

Photoelectric Sensors Get Flexible
Tru-Vue photoelectric sensors have flexible side-mounts or nose-mounts, can be surface mounted, or can be mounted like 18 mm cylindrical sensors via the threaded nose. Each has highly visible 360 deg. LEDs for status indication in all directions. Available sensing modes include background suppression, diffused, retro-reflective, thru-beam and fiberoptic. Multiple electrical connection options are available. Tamper-proof models are available to eliminate sensitivity adjustments by unauthorized personnel. Pepperl+Fuchs; 330/486-0001;
Programmable Sensor Monitors Motion
The Gemco 955 Brik Gen III programmable linear displacement transducer detects movement to 0.001 in. A simple programming unit provides calibration for changing the setting of zero and span. Its tri-color LED visual indicator verifies optimal magnet positioning, confirms active zones, and provides self-diagnostics of LDT functions. The sensor is available in a variety of transducer outputs and can be ordered in lengths to 180 in. Ametek; 800/635-0289;

On Vibration Watch
Model 685A01 electronic vibration switch provides early warning of machine deterioration and will initiate shutdown when the trip level is exceeded, preventing catastrophic damage and expensive repairs. It has an explosion-proof housing, Form C SPDT relay, adjustable trip point, local and remote reset, and continuous or latch relay operation. Operating range is 0-10 g from 10-1,000 Hz, suitable or predictive maintenance on rotating equipment. PCB Piezotronics; 800/959-4464;

Vibration Transmitter in the Loop
The HI 5701VTE loop-powered vibration transmitter provides a 4-20 mA output proportional to vibration amplitude levels of 0-1, 0-2, or 0-3 ips peak--suitable for monitoring vibration levels on rotating or reciprocating equipment. The sensor has non-polarity wiring and a power supply requirement of 10 VDC, and provides both 4-20 mA and buffered outputs. Hardy Instruments; 800/821-5831; 

More (Or Less) Power to You
The E3X-DAS fiberoptic sensor has a power tuning function that automatically shifts the power level to optimum for any sensing condition, and an Auto Power Control circuit that compensates for LED degradation. Its dual display allows users to view the set point and the current incident level at the same time. Users can change the set point while monitoring the incident level, which facilitates sensor configuration. Omron Electronics; 800/55-omron;

Programmable Position Sensor Works Backward
G-Series programmable magnetostrictive position sensors are backward compatible with the company’s existing L-Series and Tempo II sensors, and cost 10% less. LED and remote diagnostics provide sensor readings for settings, faults and output data and assist in troubleshooting and maintenance. Other improvements over existing sensors include increased shock and vibration resistance, reduced EMI interference, and improved immunity to harsh environmental conditions. MTS Systems; 919/677-0100;

Short-Range Sensor Suppression
The RPS-400-6 ultrasonic sensor has background suppression for detecting clear objects and operating in dusty environments. It is usable in short ranges of 2-6 in., and is not affected by changes in target color or material. Its small size of 0.75x2.00x1.5 in. makes it useful in tight locations. Applications include conveyors, high-speed counting, and PC board handling equipment. Migatron; 888/644-2876;

Small Scanner Sees Bar Code Labels
The CLV 405 bar code scanner measures 1.75x1.17x0.85 in., scans at frequencies up to 1,000 Hz, and has a reading range of 2-10 in. It is available in low and high-density versions, line and raster versions, and with straight and side emitting windows. Setup is via the company’s standard software. Sick; 952/829-4728;

Increase Sensitivity
Sensing ranges for M12 extended range inductive sensors are 4 mm flush mount and 8 mm non-flush mount.  Sensing ranges for M18 are 8 mm and 14mm, and 15 mm and 22 mm for M30.  The sensors have 10-40 VDC supply range, and are available in both two and three-wire versions.  Outputs are transistor types, with NPN and PNP versions available.  The housings are made of nickel-plated brass, allowing the sensors to be both robust and economical.  Carlo Gavazzi; 847/465-6100;

How Low Can Your Flow Go?
Micro Motion LF-Series Coriolis flowmeters provide mass, volume, temperature, and density measurement for liquids and gases in a flow range 0.01-28 kg/hr. Applications include those with extremely low flow rates of liquid or gas measurements, such as catalyst feeds, tinting, flavoring, and fragrancing process applications. It has analog or frequency outputs, Modbus communications, and options for HART digital communications. Emerson Process Management; XXX/XXX-XXXX;

Runs Hot and Nasty
The MIH temperature sensor can be installed in environments to 356º F with no air-cooling required and withstands harsh chemical environments, making it suitable for thermoforming, infrared and curing ovens and paint booths. It has an RS-485 interface that allows up to 32 sensors to be networked on two wires, and user-selectable 0/4-20 mA, 0-5 V, J or K thermocouple outputs. Raytek; 800/866-5478;

Gas Flow Calibration Systems
The portable Cal-Trak SL-500 and SL-800 can be used during manufacture, inspection, validation and recalibration of mass flow controllers, mass flow meters and other gas flow measurement and control instrumentation. Accuracy is 0.4% and 0.15% of reading, respectively, over a 5 sccm to 50 slpm flow range. Three interchangeable flow cells cover the entire range. Both calibrators have NIST traceability and ISO 17025 certification. Sierra Instruments; 800/866-0200;

Flow Sensor Is Cool
CoolGuard monitors the flow rate and temperature of the flowing medium and provides a solid-state switch if flow is lost or temperature is exceeded. It has no moving parts and can be mounted horizontally or vertically with no effect on the switching point. It has normally-open switching logic, is simple to install, and requires no calibration or adjustment. Weber Sensors; 770/592-6630;

It’s Hall Good 
This Hall-effect sensor for severe environmental and temperature conditions has bipolar latching sensors and a Hallogic monolithic integrated circuit, which incorporates a Hall element, a linear amplifier, and Schmitt trigger on a single silicon chip. Supply voltage is 4.5-24 V, with up to 25 ma of sink current in the “on” state. Output characteristics are constant at switching speeds from DC to more than 100 KHz. Operating temperature range is -55-125º C. TT electronics Optek Technology; 972/323-2200;

Commutation Encoder Incorporates
Model R35i small encoder provides brushless motor commutation and higher resolution incremental position signals in a 1.38x0.55-in. OD package. The three-phase (U, V, W) commutation pattern is available for four, six and eight-pole brushless motors. Incremental encoder position resolutions from 250 to 8,192 line counts are available with A, B and Z (reference) channels. Output frequency response reaches 500 KHz. Renco Encoders; 805/968-1525;

Frameless Pancake Resolvers
ULT resolvers range 3-15-in. diameter with holes 2.5-14 in. and come with an angular error map (AEM) that allows electronic compensation for mechanical errors. AEM-corrected resolvers provide absolute position information within one revolution. Operating temperatures range is -40[degree] C, and 16-bit resoultion is typical, with higher resolutions available. Applimotion; 916/652-3118;

Customized Load Cells for OEMs
Proprietary technology is applied to develop industrial load cells that can be small and sensitive in terms of electrical output/force for highly customized OEM applications. A glass-bonded, piezo-resistive silicon strain gage provides the cells with higher tension and compression for highly specialized environments. MSI Sensors; 920/854-7379;

Sensible Temperature 
Ready-to-use temperature sensors come in a variety of thermocouple and platinum RTD configurations and include both immersible and surface sensors. RTD resistances are 100 or 1,000 ohms, and lead wires are in either two- or three-wire configurations with one meter length. These sensors are suited for testing, prototype and pre-production applications. RdF; 800/445-8367;