Overview
The term “Wireless Instrumentation” is used to describe autonomous battery powered sensor systems that integrates wireless technology to enables remote sensor values to be reported to a central hub.
The central hub can be a Field Gateway that interfaces to a PLC or RTU systems; or directly to Cloud SCADA host.
Wireless Instrumentation networks are used to enable monitoring of process or environment parameters when cabling is not feasible to connect the sensors due to cost or time constraints. Wireless instruments typically monitor a single process parameter, or up multiple process variables with a multi-variable transmitter is used.
Wireless Instrumentation is typically comprised of the Wireless Instrumentation Electronics and the Sensor. The Wireless Sensor Electronics Package contains the wireless communications equipment, battery system, and sensor interface housed in a weather proof package. The sensor may be manufacturer supplied or a third party instrument.
Battery Powered
Wireless Instrumentation is battery powered to provide rapid deployment with minimum installation costs. These battery powered systems are designed to operate from 1 to 5 years between battery changes.
Wireless Technologies – Unlicensed Radio, Cellular, and Satellite
Unlicensed Radio (900 Mhz, 2.4 Ghz) Cellular, or Satellite technology is used in Wireless Instrumentation.
Unlicensed radio is typically used to provide communications from local instruments to a field gateway for use by a PLC/RTU. Cellular and Satellite technologies will direct communicate to a Cloud Host.
Licences Free Wireless Networks allow connectivity up to 1/4 miles from the sensor to field gateway. Range of the sensor can depend on the TX power of the wireless sensor, the frequency, and RF obstructions. One should always ensure a system operation with adequate fade margin to insure reliable operation.
Cellular and Satellite technologies enable connectivity to sensors anywhere where connectivity to cellular and satellite networks. Cellular technologies are ideal for municipal water applications since there would be reliable cellular coverage. Satellite technologies will be deployed in remote industrial applications like oil and gas, pipelines, or mining where there may be no reliable terrestrial coverage.
Instrumentation Signal Interfaces
The Wireless Instrumentation can be integrated devices including sensor element or Wireless Sensor nodes that interface to standard analog ( 4-20 ma, 1-5 VDC), digital (contact closures) instrumentation signal levels or data protocol (RS485 Modbus, Hart).
Wireless Instruments may be supplied complete with the sensing element. This is common for wireless instrumentation for pressure, temperature, and level (ultrasonic) measurements.
Wireless Instrumentation Measurements
Wireless Instrumentation is applied to many common industrial process measurements including:
- Pressure
- Temperature
- Flow
- Level
- Vibration
- Strain
- Sound
- Proximity
- Acoustic
Level measurement is probably the most common used Wireless Instrumentation application. Level is used to measure level liquids and material such of water levels in lake, reservoir, pits, rivers; and tanks; fuel and chemical levels in tanks and totes.
Wireless Sensor Operation
Wireless Instrumentation does not continuously transmit but transmits on the following basis:
- Schedule
- Periodic
- Event
- Demand
Scheduled transmissions transmits on specified clock times (i.e. every hour). Periodic transmission is when the system transmits periodically (i.e.one every minute) but without specific synchronization to a universal clock. Event based transmission is when the sensor transmits on a of range condition such as high, low, or excess delta. Demand transmission is when interrogation of the sensor is trigger by by the Gateway or from user initiation from the Cloud SCADA application.
The function of the wireless sensor is typically to report the process variable to the PLC/RTU or SCADA and not perform control logic.
Industrial Wireless Sensors Requirements
For industrial applications must meet the following requirements.
- Hazardous Area Classification (Class I Div 1, Class I Div 2)
- Wide Temperature Range Operation (-40 C to + 70 C).
- Water Proof Housing
- Industrial Sensors Interface (4-20 ma), Contact Closures, Modbus RTU over RS485)
- Process Interface Requirements for Sensors (Pressure, and Temperature)
Applications
Permanent, Mobile, Retrofit, and Emergency Application
Wireless Instrumentation is used for Permanent, Retrofit, Emergency, and Mobile Applications.
Plant Application
- Flare Stack Temperatures
- Pressure Relief Valves Status – Acoustic Sensors
- Engine and Compressor Run Status
- Equipment Vibration
- Tank Levels
- Pipeline Pressures
Municipal Water Applications
- Wet Well Levels
- Sump Levels
- Remote Tank Level Montoring
Hydrogeology
Oil Field Services
Agriculture
SCADALink Solutions
Fit for Purpose Wireless Sensor Solutions
SCADALink provides complete packaged Wireless Instrumentation Systems. This includes the Wireless Sensor Electronics complete integrated and tested with instrumentation, tested and ready to operate. This eliminates field integration delays and costs.
SCADALink provides Wireless Instrumentation with its monitoring and control systems including its PumpMate Pump Automation Systems.
