BRUEL & KJAER VIBROCONTROL 8000 - 20.2.2 Upscale (Normal) Direction; 20.3 Phase Trigger; 20.3.1 Direction of Rotation; 20.3.2 Event Ratio

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█ © Brüel & Kjaer Vibro ● S1079330.002 / V04

Technical alterations reserved

20.2.2 Upscale (Normal) Direction

The setting “Upscale Direction” specifies the normal (or expected) thrust direction (5). In Error!

Reference source not found. the setting would be Upscale Direction = “Away from probe”.

Axial shaft movement is predictable. Machine pressures and/or processes continuously push the

shaft the normal (or expected) direction (5).

Figure 20-3) Axial Position

The protection system detects movement at the location (1) where the sensor is installed. But since

the sensor could be installed on either side of the machine – we need to specify if the normal

movement is “towards” or “away from” the sensor.

20.3 Phase Trigger

The following settings apply specifically to Phase Trigger Channels. These are set on the Channels

tab, with the Phase Trigger (and Speed) view selected.

20.3.1 Direction of Rotation

Set the direction of rotation (Clockwise or Counter Clockwise). Direction of rotation does not affect

signal processing; this parameter is used in the CMS software. Direction of rotation is typically

determined when viewing the shaft from the driver looking towards the load.

20.3.2 Event Ratio

Event Ratio is the number of trigger pulses per shaft revolution. For a true phase trigger (with an

absolute phase reference), the event ratio must be 1.

For a probe observing gear teeth, the event ratio is the number of teeth. The Event Ratio can be set

to non-integer values (i.e. multiple gears between the transducer and the shaft).

When a multi-toothed gear is used for a phase trigger, there is no absolute phase reference. The VC-

8000 may know that there are 52 teeth (for example) but it cannot isolate to a single tooth; it is just a

string of pulses. When the machine starts and the events (pulses) start to come into the rack, the VC-

8000 will select one as a reference. On the next startup, one pulse (out of 52) will be selected as the

reference pulse for that run. Phase comparisons between runs will not be meaningful.