WiVIB1 - Wi-Fi

 

WiVIB1 uSIM Single/Three Axis Vibration Measurement for Condition Base Maintenance with WiFi (802.11)


3 Axis Accelerometer shown with stud mount

 

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 WiVIB1 uses advanced MEMS technology to provide the vibration sensor and the unit is all digital. The MEMS vibration sensor includes an on-board Analog to Digital Converter (ADC) and samples at ~ 100,000 samples per second with 22khz sensor resonance. Using the wireless communication link the user can set thresholds for vibration peaks which are anomalous. When these thresholds have been reached, an interrupt (alarm) will be sent to the microprocessor and an alert will be sent to the central control room via the 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.

 

Vibration 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  shut down the device. 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)

 

uSIM using low power WiFi radio module

 

WiFi is often used synonymously for 802.11. WiFi is supported by the WiFi alliance (www.wi-fi.org) which certifies the interoperability of 802.11 products. The standard is promulgated and enhanced by the IEEE and has gone through multiple stages of technical innovation. In most cases all upgrades to the standard are backwards compatible, so equipment with new versions of the standard will operate with older equipment.

WiFi (aka 802.11) is a master/slave wireless network. The master is called an access point and usually a gateway to the internet via an Ethernet connection. Millions of these access points are found in homes, factories and industrial sites all over the world. WiFi operates in the 2.4 Gigahertz unlicensed band at different data rates. A recent 802.11 upgrade allows operation in the 5 Gigahertz unlicensed band(802.11a). Date rates vary from less then 10 megabits/second to 600 megabits/second using the latest 802.11n standard upgrade.

The WiFi device normally operates in the master/slave network with the access point a central point of control. The user has an option to configure the wireless node as part of a mesh network similar to ISA100 and Wireless HART. This provides for redundancy and longer range since the signals can be routed to other nodes further then one hop away.

Normally WiFi is used as a backbone device because of its relatively high performance and high power consumption obviating its use with batteries.

WiHART Systems has introduced an extremely low power WiFi module which reduces normal WiFi power consumption by a factor of 5 or more. This allows for the utilization of WiFi in battery powered nodes.  It can be utilized in conjunction with the WiHART System industrial WiFi access point and backbone networking device.

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.

uSIM WiFI Implementation

The uSIM WiFi implementation is accomplished by adding an additional WiFi radio module to either the uSIM-15.4(Zigbee) or the uSIM-ISA100. The uSIM-15.4(Zigbee) or the uSIM-ISA100 radios can be shut down and placed in the sleep mode if desired. The 802.11 radio can either be the primary radio on the node or used in conjunction with the IEEE 802.15.4 radio (Zigbee or ISA100). The WiFi radio can be used as the direct link to the backbone in a WiFi sensor network.

 

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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