Facts Established by Phase: Frequency Confirmation

Fact #1: The vibration IS (or IS NOT) coming from the shaft First, you must remember that the strobe light is actually being triggered by the vibration signal. Every time the analyzer detects a peak signal from the transducer, it instructs the strobe light to flash. The strobe flash will, therefore, flash at exactly the same rate as the vibration is occurring. Second, mechanical vibration - i.e. vibration being generated by the rotation of the rotor - occurs only at exact multiples (harmonics) of the rotational speed (rpm). These vibrations are known as synchronous vibrations. Third, sources of vibration other than the rotor - belts, bearings, electrical vibrations and other non-synchronous vibration sources will not generate vibration at exact multiples of the rotational speed. This is true regardless of how close they are to being synchronous. Even if the adjacent machine is running at 0.1 rpm different speed, it is still a different speed - it is still non-synchronous. Since the strobe is flashing at exactly the vibration frequency being generated, whether or not the mark (shaft) appears frozen under the strobe light reveals whether the vibration is synchronous or non-synchronous. This test will be referred to as a:

Frequency Confirmation

Frequency confirmation simply means you are confirming the source of the vibration is the rotor that appears frozen under the strobe flash and it is the ONE use for a single phase reading.

Frequency confirmation is a simple test that requires only a few seconds to perform but can be crucially important to the successful diagnosis of a machine's problem.