一、 Industry background of escalator monitoring system
In recent years, China's urban rail transit has developed rapidly, but there have also been multiple accidents resulting in significant casualties due to mechanical failures of escalators. To avoid major accidents, it is necessary to establish an escalator fault monitoring system to promptly detect escalator equipment failures. This plan aims to establish a health monitoring system for escalators, which monitors the vibration, speed, temperature, and current of components such as motors, reducers, drive wheels, and handrails. Through joint analysis of relevant indicators, a database is established to monitor changes in relevant indicators before equipment failure occurs, detect alarms in a timely manner, and issue warnings to avoid major accidents. The system consists of several parts, including front-end sensing system, high-precision data acquisition instrument, online monitoring software, and network transmission system.
二、 The monitoring purpose of the escalator monitoring system
Due to wear and tear of bearings, guide rails, and other components, the escalator may experience excessive vibration during operation. Prolonged vibration may cause the fixing bolts to loosen or break, resulting in serious accidents such as the displacement of the drive host. The damage of mechanical equipment often has a gradual development process. In the early stages of failure, it cannot be seen from the appearance. When the degree of damage develops to a certain stage, a major accident of machine destruction and human death may suddenly occur. However, early equipment failures, such as bearing or gear wear, have already been reflected in vibration signals and can be detected early through appropriate data processing. Therefore, sensors can be installed at key components to monitor different faults.
三、 The role of sensors in the escalator monitoring system
(1) Monitoring objects and sensors
Vibration acceleration sensor: The vibration acceleration sensor monitors the vibration signals of various mechanical components. When bearings, gears, tracks wear or anchor bolts loosen, the vibration signals will change. By extracting characteristic indicators such as peak to peak value, kurtosis index, effective value, main frequency amplitude, low-frequency or high-frequency amplitude, and combining them with analysis methods such as cepstral and envelope spectrum, the early characteristics of faults can be effectively captured.
(2) Dynamic data acquisition device
This scheme adopts the internationally mainstream 24 bit AD high-precision and high dynamic range data acquisition instrument to perform analog-to-digital conversion and preprocessing on the sensor signals. This monitoring type data acquisition device adopts windproof, dust-proof, moisture-proof, and strong anti electromagnetic interference design, which can meet the requirements of relatively harsh on-site environments. There are multiple escalators on the rail transit platform, and data collection devices can be distributed to collect data separately.
4、 Automatic escalator monitoring system sensor products from Senther Technology
310AT temperature vibration integrated sensor:
The 310AT series product is an industrial IEPE accelerometer for temperature and vibration synchronous measurement. Its characteristic is to use ceramic crystals with a circular shear mode as the sensitive element, which has the ability to maintain stable output for a long time. The internal circuit of this acceleration sensor provides constant current source excitation and transmits low impedance voltage output signals simultaneously on the two-wire system of the IEPE system. The integrated temperature sensor transmits temperature signals through voltage signals, and the signal ground is internally shielded and isolated from the housing; At the same time, the design of the signal amplification circuit considers polarity reversal protection.The shell adopts laser welding technology to ensure the sealing of the product; The output connector adopts standard MIL-C-5015 glass insulated connector to meet the stability of output when used in different environments. In addition to adhesive installation, the 310AT series accelerometer also provides 1/4-28 threaded holes for secure installation; The 310AT series accelerometer has the characteristics of wideband response and shock resistance, making it an ideal accelerometer for industrial vibration monitoring and measurement in harsh environments. In addition, Senser Technology also provides cables that are compatible with standard MIL-C-5015 connectors, with models 20A-L available for selection,
IN-SDG data collector:
The IN-SDG intelligent vibration transmitter is developed based on the transformation of equipment manufacturers to operation and maintenance providers, the introduction of the concept of the entire equipment lifecycle, the concept of big data and artificial intelligence, the concept of smart factories, changes in communication methods, and the emergence of 5G applications. The IN-SDG intelligent vibration transmitter is mainly used to detect large sliding bearing equipment, such as steam turbine generators, large axial flow fans, and large air compressor units. Rolling bearing equipment with gearboxes, such as wind turbines, rolling mills, various pumps, and blowers.
After long-term monitoring of the equipment, the operating status data of the equipment in each period will be continuously accumulated. Based on these historical data, a fitting curve of the data will be obtained through fitting methods, which can reflect the trend of data changes, that is, the trend of equipment operating status changes. Usually, as the device is used for a longer period of time, its condition deteriorates due to wear and tear, and the vibration data continues to increase. Based on the trend curve, we can understand the rate of equipment degradation and predict whether it will reach or exceed the danger threshold in a certain period of time in the future. Trend prediction can predict and take appropriate maintenance measures in a timely manner before the equipment reaches damage, achieving predictive maintenance of the equipment.
