WiVIB1 - ISA100

WiVIB1 uSIM Single/Three Axis Vibration Measurement for Condition Based Maintenance using ISA100 Wireless Mesh Network

 

3 axis MEMS Accelerometer

 

Introduction

The WiVIB1 (See Appendix for block diagram) is the first in a series of wireless micro sensor interface modules (uSIM) with a broad range of wireless options. The WiVIB1 is a revolutionary “game changer” wireless vibration monitor/switch device which measures about ~1 square inch including sensor, radio and advanced RISC processor. It operates under battery power. It is available in both single axis and three axis versions.

The WiVIB1 presently has three(3) radio options

  1. WiVIB1- 15.4 - IEEE 802.15.4 radio at 2.4 gigahertz (Zigbee)
  2. WiVIB1- ISA100
  3. WiVIB1- WiFi - IEEE 802..11 ultra low power 802.11 b/g radio

 

Each of these modules are available in single axis and three axis configurations. The WiVIB1 is a device for condition based maintenance vibration analysis and a vibration switch in one tiny package.

The WiVIB1(pronounced why vibe one) does not use any external wires and does not use a traditional remote piezoelectric sensors attached to the vibrating machine with a wire. The unit is so small (about 1 square inch, the size of a postage stamp) it mounts directly on the vibrating device and sends the information via a wireless link.

The unit can also be used as a wireless switch to activate a  solid state relay (SSR) to shut down the vibrating device in distress and send a message to the control room.  We now have a vibration switch which gives notification to the control room that the motor, etc. has been deactivated and continuous status reports can be sent.  If the device was shut down due to anomalous behavior it can be restarted from a remote location.

Please note that in the past MEMS accelerometers did not have the bandwidth and sampling rates to do vibration analysis comparable to piezoelectric sensors.   This is no longer true and MEMS accelerometers can match and even exceed the capabilities of piezoelectric accelerometers.

 

WiVIB1 as Vibration Switch

What is a Vibration Switch

A vibration swich is a device that recognizes the amplitude of the vibration and provides a predetermined response when the amplitude exceeds a preset threshold.

Solid State Relay

The wireless switch can be use to activate a solid state relay (SSR) to shut down the vibrating device in distress and send a message to the control room. We now have a vibration switch which gives notification to the control room that the motor, etc. has been deactivated and continuous status reports can be sent. If the device was shut down due to anomalous behavior it can be restarted from a remote location.  Since the vibration switch is microprocessor controlled various time delays can be programmed.

 

Wireless Switch with Solid State Relay

Since WiHART Systems adheres to a “no wires” design architecture the WiVIB1 can operate as a vibration switch with a wireless remote power control.   Traditional vibration switches utilize a long wire to reach the power control of the device to be shut down.  The WiVIB1 can utilize a wireless solid state relay as a separate remote radio unit.  When the vibration sensor encounters an anomaly and wishes to shut down the device it sends a wireless message to the solid state relay(SSR) (standard part is 660 volts at 5 amps, optional SSR is 25 amps).  If the power cutoff is close to the sensor then the SSR can be packaged with the sensor and a short wire can be added.


The WiVIB1 is 100% digital and can be programmed and configured over the radio with multiple set-points and alarm types.

Solid State Relay

The solid state relay(SSR) is rated at 5 amps at 660 volts. An optional SSR is available that is rated at 25 amps at 660 volts  Lower power devices such as analog switch devices are also available (contact factory)

ISA100

ISA100 operates in the 2.4 Gigahertz band using the IEEE 802.15.4 radio standard with direct sequence spread spectrum communication. It is a mesh network with redundancy. The standard was primarily established for use in process control applications but there are working groups for factory automation applications. The standard may use TDMA (Time Division Multiple Access) to transmit information. TDMA assigns slots in the communication channel for data transmission and reception of data. ISA100 also has the capability to use CSMA/CD which does not require accurate clock synchronization. The standard also utilizes a frequency agility technique to minimize interference on the network. The IEEE 802.15.4 standard defines 12 channels for hopping.

ISA100 is not an ad hoc network in the sense it requires both a centralized network manager and security manager.  The Network Manager is responsible for configuring the network, scheduling communications between devices, managing message routes, and monitoring network health.

Fast Fourier Transform (FFT)

The WiVIB1 will execute an FFT (Fast Fourier Transform) locally to obtain frequency spectrum. The WiVIB1 does not require a back end processor to generate a frequency spectrum from the time domain data.

3 Axis acceleromter

 

The WiVIB1 is available with a 3 axis accelerometer in one small module and does not require 3 external piezoelectric devices requiring additional power hungary electronics to obtain the vibration data.  The 3 axis accelerometer pictured above is shown with stud mounting.  The single axis unit is connected directly on the printed circuit board.



ACCELEROMETER FEATURES

  • Digital ±70 g accelerometer/vibration sensing
  • 22 kHz sensor resonance
  • 100.2 kSPS sample rate
  • SPI-compatible serial interface
  • Programmable data capture function:
  • Manual trigger for user initiation
  • Automatic trigger for periodic data capture
  • Conditional trigger for condition-driven capture
  • Digital temperature sensor output
  • Digitally controlled sample rate
  • Digitally controlled frequency response
  • Digitally activated low power mode
  • Serial number and device ID
  • Operating temperature range: -40C to +125C
  • Solid State Relay



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