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6.13.1 Rotational Speed Sensor Selection
It is recommended to use either an NPN or PNP type, i.e. a standard interface that all rotational
speed sensor suppliers meet with a variety of different probes.
Only three wires are needed: DC supply sensor, signal and ground.
Some suppliers refer to NPN and PNP type rotational speed sensors as "3-wire DC."
6.14 Alert and Danger Alarms
The final task associated with setting the parameters of each function, such as vibration, process
and RPM measurements, is to define the alarm values. There are two alarms attached to each
vibration measuring function: an Alert alarm and a Danger alarm.
The alarm output in the VC-18xx will only respond if the alarm function is enabled in the
measurement tasks.
The parameter setup of the Alert alarm and the Danger alarm are very similar and consists of
setting the following parameters:
•
Alarm Limit Type
A High Limit Alarm or Low Limit Alarm can be defined. For normal operation (= default) an alarm is
set for the high limit value. The alarm is triggered as soon as the measured value exceeds the pre-
set limit value of the respective alarm and that state is present for longer than the set delay time.
Alarms can generally be based on overrunning or underrunning the limit values.