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For example, if you set 0% open to correspond to 5 mA and 100% open to correspond to 17 mA, the
FullScaleVoltageChange is (17 mA – 5 mA) * 249 = 2.988V.
The BottomScaleInputVoltage would be 5 mA *249 = 1.245 V.
Where the 249 factor is the impedance the UMM uses to convert from current to voltage.
22.2.4 Verifying nX Amplitude and Phase
Follow the instructions in this section to verify:
• Radial Vibration 1X, 2X, nX Amplitude and Phase
• Velocity 1X, 2X, nX Amplitude and Phase
• Acceleration 1X, 2X, nX Amplitude and Phase
Use the measurement equipment set up shown in Figure 22-4
Figure 22-4) nX Vector Test Set Up
You will need a function generator capable of two outputs that are synchronized, with the ability to
vary the frequency between the two waveforms. You can use the Sync output for the Phase Trigger
input if the Phase Trigger channel is configured for “+18V Proximity Switch”.
Set the DC bias on the function generator within the OK limits for the transducer. Connect one
function generator channel to the Phase Trigger input and the other to the channel under test. If the
function generator cannot support the offset required for the signal to be in the OK range, you can
offset the function generator using a power supply.
Set the Phase Trigger frequency to the machine running speed/60 Hz. Set the channel input
frequency “n” times the Phase Trigger frequency.
Example:
If the machine speed is 3600 rpm, set the Phase Trigger frequency to 60 Hz. Set the input
frequencies as shown in Table 22-2.
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