Protection
Measurement Types
SKF Multilog On-Line System IMx-M
2 - 15
User Manual
If start and stop angles are configured close to the end of the
revolution (360
) special care should be exercised to make sure that
Measurement Angles and Non Constant
) will not cause the measurement to be terminated early or
not performed at all.
Measurement Angles and Non Constant Speed
During a speed change an error in the measurement can be introduced. When
the speed stabilizes the actual angles will again be the same as the configured
and the measurement will be true.
Increasing speed:
The angles between which the measurement is performed will be
amplified. The measurement will be such as if both start and stop angle had
greater values than configured.
The measurement window will be wider than configured.
In the extreme case, the measurement could be terminated early or not be
performed at all. This condition happens when there is an extreme speed
change so that the derived start angle and/or stop angle is reached after a new
trigger pulse is received.
Decreasing speed:
The actual measurement will be performed earlier in the revolution than
configured.
The measurement window will be narrower than configured.
The following is an example of how the configured measurement angles are
translated to actual angles during constant speed, increasing speed, and
decreasing speed. In triggered mode the measurement is the mean of the
samples collected between the configured start angle and stop angle. The
reference point (0
) is the point where the speed sensor will deliver a falling
edge to the digital input.