Speed measurement Part C VC-6000
TM
Compact monitor
© VC-6000
TM
Compact monitor Sept.2011 C100583.002 Components Vers. 07 - 29 -
8 Speed measurement
8.1 Function
♦ The Speed measurement is a signal path component to accurately
acquire a scalar measured value, e.g. the rotational speed of a shaft or
the time span between two trigger signals.
♦ The Speed measurement block, as a configuration interface, contains all
the parameters required for setting up.
♦ The Speed measurement always needs the output signal (trigger event
sequence) from a preceding Trigger block in the signal-flow chart.
♦ As a rule the physical measurement unit for the speed measurement is
defined as [rpm] and cannot be changed at the instrument.
Configurations can also be prepared with the units [cpm], [Hz], [s] or
[ms] .
♦ During the progress of the measurement the results of the speed
measurement are updated without any time delay. The current
measurement can be read through the User Terminal.
♦ The current measurement can also be fed through an analogue DC
output to downstream electronic equipment.
♦ The current measurement can also be read through the COM interface
of a downstream OPC-server.
♦ The speed measurement can be monitored through one or more
Monitor blocks for speed limit violation.
♦ The speed measurement is based on a frequency measurement:
Speed [rpm] = 60 * 1/p * f f = Trigger frequency in Hz
p = Trigger events per revolution
In the case where a gearbox is used:
Speed [rpm] = 60 * 1/g * 1/p * f f = Trigger frequency in Hz
p = Trigger events per revolution
g = Transfer ratio
When only one time period is to be acquired:
Period [ms] = t / n t = total measurement time in ms
n = Number of completed cycles
♦ The signal flow component for speed measurement is used for various
applications, e.g. speed measurement, overspeed protection, zero rpm
identification, etc.
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