Application and solutions of sensing technology in industrial automation

Sensing technologies play critical and complementary roles in industrial automation applications

In industrial automation applications, thermistors, MEMS sensors, and vibration sensors each play critical and complementary roles, collectively building the foundation for intelligent monitoring and precise control.
 
Thermistors are primarily responsible for temperature monitoring and control. They can sense temperature changes during equipment operation in real-time, used for temperature protection and energy efficiency management in motors, power modules, heating systems, and production environments, ensuring stable and safe equipment operation.
 
MEMS (Micro-Electro-Mechanical Systems) sensors are characterized by miniaturization, high sensitivity, and multi-functional integration. They can simultaneously measure parameters such as pressure, acceleration, tilt angle, gas, or flow, and are widely used in mechanical structure monitoring, positioning control, and equipment motion analysis, enhancing the system's intelligence level.
 
Vibration sensors are the core of equipment health management. They can detect minute vibration changes during mechanical operation, used for predictive maintenance, fault diagnosis, and production stability analysis, preventing downtime and damage.
 
The comprehensive application of these three sensing technologies enables industrial systems to achieve closed-loop management from state perception to intelligent decision-making, and then to autonomous control, significantly improving production efficiency, reliability, and operational intelligence. By integrating these sensing technologies with intelligent algorithms, edge computing, and industrial IoT platforms, enterprises can build more efficient, safer, and more predictive automation systems, driving the continuous development of smart factories and Industry 5.0.

Thermistors for temperature detection and overcurrent protection in industrial automation

Murata offers a variety of negative temperature coefficient thermistors (NTC) and positive temperature coefficient thermistors (PTC) for temperature detection and overcurrent protection in industrial automation. For instance, the chip NTC product line is used for temperature detection, featuring diverse sizes, high accuracy, and high reliability, operating within a temperature range of -40°C to 125°C. This includes the NCP/NCU series, with models such as 0402, 0603, 1005, 1608, supporting resistances like 10kΩ/47kΩ/100kΩ, etc., and resistance tolerances of ±0.5%/1%.
 
The chip NTC thermistor NCP02 series measures only 0.4 x 0.2 x 0.2 mm, includes resistances from 10kΩ to 470kΩ, and supports high accuracy 10k/100kΩ. The NCP03 series measures 0.6 x 0.3 x 0.3 mm, includes resistances from 10kΩ to 470kΩ, and supports high accuracy 10k/100kΩ. The NCU03 series measures 0.6 x 0.3 x 0.3 mm, includes 10kΩ and 100kΩ types. The NCU15 series measures 1.0 x 0.5 x 0.5 mm, includes an expanded lineup from 220Ω to 470kΩ, and supports high accuracy 10k/47k/100kΩ. The NCU18 series measures 1.6 x 0.8 x 0.8 mm, includes an expanded lineup from 220Ω to 470kΩ, and supports high accuracy 10k/47k/100kΩ. The FTN21 series measures 2.1 x 1.2 x 0.85 mm, features wire bonding and high-temperature guarantee (~175°C), and includes versions for solder mounting (5kΩ, 10kΩ/100kΩ) and Ag sintered mounting. The aforementioned products feature high accuracy (25°C resistance: ±1%, ±0.5%), an operating temperature range of -40°C to +125°C, UL/cUL, IEC(TUV) certification, stable quality through integrated production from raw materials, and world-leading production and supply capacity.
 
Furthermore, the chip PTC product line can be used for over temperature detection, featuring simple detection circuits and a wide detection temperature range. For example, the PRF series (0603, 1005, 1608, 2012) offers a detection temperature range of 65°C ~ 145°C, with detection accuracy of ±3°C/±5°C, enabling overheat detection without a microcontroller.
 
Murata's chip PTC thermistor PRF03 series measures 0.6 × 0.3 × 0.3 mm, supports detection from 95°C to 125°C, 10 times point ±5°C. The PRF15 series measures 1.0 x 0.5 x 0.5 mm, supports detection from 95°C to 125°C, 10 times point ±5°C and 100 times point ±3°C. The standard type PRF18 series measures 1.6 x 0.8 x 0.8 mm, supports detection from 65°C to 145°C (in 5°C increments), 10 times point ±5°C and 100 times point ±7°C. The narrow deviation type PRF18 series measures 1.6 x 0.8 x 0.8 mm, supports detection from 65°C to 115°C (in 5°C increments), 10 times point ±3°C and 100 times point ±7°C. These products enable simple and cost-effective overheat detection circuits, offer excellent noise immunity, and allow detection of multiple heating points with a single circuit via series connection. They are UL/cUL, IEC(TUV) certified.
 
Additionally, Murata's chip PTC product line can be used for overcurrent protection, featuring stable characteristics, resettable, and high power capacity (compared to resistors). For example, the PRG series (0603, 1005, 1608, 2012) has a hold current range of 10mA ~ 750mA @ 25°C, providing overcurrent protection without disconnection.
 
Murata's chip PTC thermistors for overcurrent protection include the PRG03 series, measuring 0.6 x 0.3 x 0.3 mm, supporting 15V/20V, hold current 14mA/19mA. The PRG15 series measures 1.0 x 0.5 x 0.5 mm, supporting 6V to 30V, hold current 26mA to 134mA. The PRG18 series measures 1.6 x 0.8 x 0.8 mm, supporting 6V to 30V, hold current 10mA to 330mA. The PRG21 series measures 2.0 x 1.25 x 0.9 mm and 2.0 x 1.25 x 1.25 mm, supporting 6V to 32V, hold current 54mA to 750mA. These products feature resistance returning to the original state once the overcurrent is removed, are UL/cUL, IEC(TUV) certified, ideal for short-circuit tests per safety standards, exhibit stable characteristics before and after overcurrent protection operation, offer larger power capacity and more compact size compared to chip resistors of the same dimensions, and can be used as current-limiting resistors.

Murata offers a range of MEMS sensors tailored for industrial automation applications, covering accelerometers, inclinometers, and gyroscopes (combo sensors integrating gyroscopes and accelerometers), focusing on applications such as Structural Health Monitoring (SHM), robotics, drones (eVTOL), and heavy machinery.
 
For example, the SCA3300 and SCL3300 are single-package 3-axis high-performance MEMS sensors, featuring unique mechanical over-damping technology, employing industry-proven technology with significantly improved performance. They feature an SPI digital interface, stable output over lifetime across a wide range of temperatures and vibration environments, compliance with RoHS and EV directives, and advanced self-diagnostic functions. The SCA3300 and SCL3300 measure 7.6 x 8.6 x 3.3 mm, use a 12-pin pre-molded housing suitable for SMD mounting, offer user-selectable measurement modes, feature ultra-low noise density, operate from -40°C to +125°C, use a 3.0V ~ 3.6V supply voltage, and consume only 1.2mA current.
 
Murata's new SCA3400 XYZ accelerometer (3DoF) offers excellent total offset performance over its lifetime and temperature. The SCL3400 XY accelerometer (2DoF) is suitable for static measurement scenarios. The 3400 series is pin-to-pin compatible with the SCA/SCL3300 series. The SCA/SCL3300 XYZ accelerometer (3DoF) is suited for applications demanding high stability under tough environmental requirements.
 
The SCL3400 is a 2-axis high-performance digital platform inclinometer (XY-axis pitch & roll), pin-to-pin compatible with the SCA/SCL3300 series. It boasts excellent total offset performance over lifetime and temperature, with temperature dependency ≤ 2.5 mg, typical offset drift over lifetime ≤ 0.05° @ RT, and ultra-low noise density of 0.0009°/√Hz (16µg/√Hz). It supports user-selectable measurement modes including ±30° / 32768 LSB/g with 10 Hz LPF and ±90° / 16384 LSB/g with 40 Hz LPF. It features a digital output (SPI interface) and advanced self-diagnostic functions, operates from -40°C to +85°C, uses a 12-pin pre-molded SOIC package measuring 8.6 x 7.6 x 3.3 mm, has a supply voltage range of 3.0 V to 3.6 V, and consumes only 2.1 mA current.
 
For the Murata SCH16T series gyroscope, the guaranteed specification range is ±300°/s, with a typical output range of ±327.5°/s, featuring low noise and stability over temperature and lifetime. For the accelerometer part, it supports a guaranteed specification range of ±8g, with a typical output range of ±26g, featuring stability over lifetime and temperature, as well as excellent shock and vibration resistance. It is suitable for precision agriculture, automated steering of farming machinery, construction machinery control, bulldozer/grader blade control, paver inclination measurement, excavator scoop control, platform stabilization, harvester cabin leveling, forklift load leveling, satellite antenna and compass compensation on moving platforms such as ships, vessels, and vehicles, construction surveying poles, and IMU for positioning and orientation information (with GNSS), applicable in robotic navigation/autonomous vehicle navigation subsystems, Automated Guided Vehicles (AGVs) in warehouses, and road geometry & surveying, pavement inspection.

Vibration sensors enable predictive maintenance for production equipment

In industrial automation applications, equipment maintenance is crucial for overall system stability. The trend in equipment maintenance has evolved from traditional reactive maintenance and planned maintenance to predictive maintenance. Predictive maintenance can be divided into proactive TBM planned maintenance (preventive maintenance), including periodic and time-based maintenance. Alternatively, CBM predictive maintenance (Condition-Based Maintenance) can be adopted, utilizing methods like image recognition, temperature detection, vibration monitoring, sound monitoring, and current detection to assess equipment pre-failure conditions. By collecting data through sensors, it predicts when and what kind of failure might occur in machine components, allowing for part replacement before failure. Applying CBM maintenance to vulnerable parts/critical equipment effectively enhances maintenance convenience.
 
In predictive maintenance, machine condition changes over time, and abnormal vibration is often the first sign of change. By monitoring abnormal vibrations, problems can be detected and corrected promptly (e.g., scheduling maintenance, replacing parts). Multi-axis MEMS accelerometers are primarily used to detect low-frequency vibrations, often corresponding to states where equipment failure has already occurred. To achieve predictive maintenance, sensors capable of detecting high-frequency vibrations are needed.
 
Murata's PKGM-200D-R, in a compact SMD form factor, is ideal for mounting on mechanical components and can detect high-frequency vibrations up to 11 kHz, aiding in the predictive maintenance of bearings, etc. The drive circuit for the PKGM-200D-R is built into the small package. By detecting vibrations in the high-frequency band, it can detect vibration anomalies before abnormal noise and heat generation occur.
 
The PKGM-200D-R measures 5.0 × 5.0 × 3.5 mm, uses a 7-terminal, SMD package structure, and combines an acceleration sensor with a thermistor temperature sensor. It can detect high-frequency vibrations up to 11 kHz, which is more conducive to early symptom monitoring. It performs Z-axis single-axis vibration monitoring, has a built-in drive circuit, uses dual differential output to reduce noise, and includes a thermistor temperature sensor. The PKGM-200D-R is suitable for vulnerable mechanical parts such as gears, bearings, machine tools used in industrial automation, and is also used for overall predictive maintenance of equipment like motors. It targets vibration collectors for industrial automation and can also be used by IoT companies for predictive maintenance.
 
Another model, the PKGX-20-4040 (PN under development, mass production product expected to be named PKGM-210D-R) single-output vibration sensor, is expected to enter mass production by the end of 2025. While maintaining the dimensions of 5.0 × 5.0 × 3.5 mm, it uses a 7-terminal, SMD type, combining an acceleration sensor with a thermistor. It supports an ultra-wide frequency range (20 kHz), Z-axis detection, has a built-in drive circuit, provides a single analog output, and includes a thermistor temperature sensor.
 
Murata's vibration sensors contribute to predictive maintenance in factory industrial automation by helping to extend equipment lifecycle, reduce losses due to unexpected equipment failures, and decrease equipment part repairs. Murata also provides samples of vibration sensors and evaluation boards to accelerate customer product development.

Conclusion

The integrated application of thermistors, MEMS sensors, and vibration sensors is becoming a new engine driving industrial automation towards greater intelligence and reliability. With the further maturation of Industrial IoT (IIoT), edge computing, and AI data analytics technologies, the integrated solutions of these three sensor types will continue to expand application boundaries, helping enterprises build smarter, more energy-efficient, and more competitive automation systems to meet the new challenges and opportunities of the Industry 5.0 era. The aforementioned Murata thermistor, MEMS sensor, and vibration sensor product lines will be excellent solutions for building your industrial automation systems.