Sensor selection: Consider more than capital costs

Spending a little more time, effort, and money in sensor selection can pay off significantly in the lifecycle costs of the sensor or switch, according to Honeywell Sensing and Control. Tips and Tricks: Learn the five misconceptions about sensing.

By Mark T. Hoske August 15, 2011

When selecting a sensor, look beyond capital costs to get the lowest lifecycle cost, suggested Brad Kautzer, vice president and general manager of electromechanical business, Honeywell Sensing and Control. 

Five common misconceptions about sensing involve justification, power requirements, intelligence, safety, and networking, Kautzer said. He discussed each point further, below.

1. Justification. “Key business drivers are productivity, safety, energy consumption, time-to-market, and cost competitiveness. The question is, ‘How to achieve optimal balance between component cost and the benefits that can be achieved by the customer’s customer,’ ” Kautzer said.

Sensor benefits are realized by end users but delivered through the value chain. “In this competitive environment, original equipment manufacturers (OEMs) may overlook the advantages that a small sensing investment can bring to their end-user customers. We try to quantify those savings.”

A palletizer manufacturer, for instance, has a cost in mind in order to compete with other machines in the market and has to translate and quantify the benefits for its customers. If it included sensors in its equipment, it could realize reduced downtime costs, increased diagnostic capabilities, and increased machine productivity. Sensors can say where and how a failure occurred.

Sometimes, an even more robust option is best for the application. A heavy-duty limit switch costs 5% to 10% more, perhaps $35 instead of $30, but can bring orders of magnitude more in benefits.

Wireless sensors can help many sensing applications. In a rotating paper-making application, there’s high shock and vibration and higher reliability with wireless sensing. In construction, a boom or crane can have wires that fray, break, or get caught on things. In process monitoring, additional monitoring points enabled by wireless allows for additional productivity gains. More points bring more data to enable the next level of productivity, but data must be actionable, Kautzer said. Wireless is an enabler, and higher reliability is the benefit.

2. Low power. There’s a greater awareness of the shrinking power budget for elements lowest in the value chain. Low-power sensing creates greater energy savings for battery-based devices, with many opportunities, especially in process industries with wireless transmitters. Automated (rather than manual) sensing can add 1%-2% to overall productivity, and wireless technologies provide a low-cost means to sense more points. Reducing maintenance by lowering power requirements is a big deal. A switch can eliminate power draw until the device operates, in some cases extending battery life to 5 years. 

3. Smart sensors can deliver intelligence for better decision making on the factory floor. Sensors can serve data into cloud computing and mobile applications to improve productivity and decrease energy consumption. Sensor data is a key source of information. Using sensors with electronic data sheets inside helps put intelligence in the device. Wireless switches or sensors can effectively improve processes without overwhelming those involved with data. Examples include sending a signal when flume hoods are open and not in use, so they can be closed to save energy. In machine monitoring, data can be sent to the maintenance system when something needs attention. An alert also can be sent to smart mobile devices.

4. Safety. The challenge around safety is to balance the protection of operators, machine specifications, laws, and insurance against productivity. The perception is that safety reduces productivity. Our goal is to provide important safety functions to protect operators and improve the productivity of the machine. As an example, production in Asia is very price-driven. An appropriate selection of sensor products can result in a decrease in overall system costs. 

5. Networks. Networking multiple switches inside machines to one I/O point can also save time and the cost of wiring. There are bundles of wires in machines, and smarter components and designs can save resources during building, commissioning, factory acceptance tests (FAT), and on-site testing, and in machine troubleshooting later.

Applications, no recalibration

Built-in sensor stability has eliminated the need for sensor recalibration. “Needs that were previously unmet can be resolved with the integration of sensing technologies. By combining sensing technology with enabling wireless, new applications can be solved,” Kautzer said.

Honeywell TruStability capabilities put compensation in sensors, explained Ashis Bhattacharya, Honeywell vice president global strategic marketing and business development for sensing and control. Previously, Bhattacharya noted, calibration had to be performed with an expensive calibrator. One temperature and humidity sensor, for instance, is guaranteed for total error plus or minus 1%, compensated and calibrated.

Applications where wireless can be particularly useful include oil and gas, test rigs for automotive and aerospace components, measuring temperatures to anticipate pump bearing failure, and even something as simple as monitoring if a door is closed, Bhattacharya said. “Sensors are enabling devices. We must go beyond the component mind-set.”

New sensing products

A range of offerings helps get beyond thinking about components, Kautzer said. Honeywell products have multiple ranges of performance that can be aligned with business objectives, such as rugged products for critical applications or midrange products for the “good-enough” applications. Investments in product development continued during the downturn, creating products for specific needs and standards-based wireless solutions for ISA100, IEC 802.15.4, and others. A platform approach allows for rapid configuration and short response times to modifications. 

Honeywell Sensing and Control provides electronic sensors for pressure, thermal, speed, and position applications; electromechanical devices, such as switches, controls and monitoring and precision aerospace products; and test and measurement devices for pressure, load, torque, and instrumentation. Honeywell product introductions in 2011 included: Smart Position Sensor Arc Configuration; Micropolar Omnipolar Hall- Effect Sensor ICs; Hawk Resolver, 1-Inch Series; the Limitless Wireless Din-Rail Receiver (WDRR); TruStability Board Mount Pressure Sensors: NSC Series; and TruStability Pressure Sensors Liquid Media.

In 2010, Honeywell Sensing and Control introductions included: SS361CT/SS461C High Sensitivity Hall-Effect Sensor ICs, Zephyr Airflow Sensors, Limitless WGLA and WLS Series Limit Switches, Micro Switch Stainless Steel Hazardous Area Switches, XYR6000 Wireless Position Sensors, Smart Position Sensor, 225 mm Linear Configuration, Limitless WPMM Series Panel-Mount Monitor, Relialign Door Interlock Switches, and new configurations of the TruStability Pressure Sensor.

– Mark T. Hoske, CFE Media, Control Engineering,  

Also see:

– Uncompensated, unamplified, board-mount pressure sensors  

– Video: Commoditizing wireless communication 

– Wireless Application: Western refining cuts wiring costs, improves performance 

– 1-inch series resolvers offers fully housed configuration 

Author Bio: Mark Hoske has been Control Engineering editor/content manager since 1994 and in a leadership role since 1999, covering all major areas: control systems, networking and information systems, control equipment and energy, and system integration, everything that comprises or facilitates the control loop. He has been writing about technology since 1987, writing professionally since 1982, and has a Bachelor of Science in Journalism degree from UW-Madison.