Rockwell Automation 1440-VSE02-01RA XM-122 gSE Vibration Module - Manual (Page 209)

Publication GMSI10-UM013D-EN-P - May 2010
Glossary 199
Spike Energy
Spike Energy is a measure of the intensity of energy generated by transient or
mechanical impacts. These impacts or pulses typically occur as a result of
surface flaws in rolling-element bearings, gear teeth, or other metal-to-metal
contacts, such as rotor rub, insufficient bearing lubrication, etc.
Spike Energy measurement utilizes an accelerometer to detect the vibration
energy over a pre-determined high frequency range. The mechanical impacts
tend to excite the mounted natural frequencies of the accelerometers as well as
the natural frequencies of machine components and structures in this high
frequency range. These resonant frequencies act as carrier frequencies and the
bearing defect frequency modulates with the carriers. The intensity of impact
energy is a function of pulse amplitude and repetition rate. The signal induced
by such impacts can be measured by accelerometers and processed by a unique
filtering and detection circuitry. The measured magnitude of the signal is
expressed in "gSE" units (acceleration units of Spike Energy).
startup/coast-down trend
A speed-base trend that is collected in an XM module during the startup or
coast-down of a machine when the measured machine speed crosses into a
defined speed range.
strobe
See Bit-Strobe.
transducer
A transducer is a device for making measurements. These include
accelerometers, velocity pickups, displacement probes, and temperature
sensors.
trend
A set of records of one or more measurement parameter(s) collected at regular
intervals based on time or speed.
trigger
An event that prompts the collection of trend data.
triggered trend
A time-base trend that is collected in an XM module when a relay on the XM
is activated, or when the module receives a trigger event.