Vibration Comparator Frequently Asked Questions

The VC-2100 vibration comparator has four measurement modes: RMS, PEAK, MAXHOLD, and PEAK HOLD. These modes are displayed on the screen when switched between. The comparator compares the value shown on the screen (the displayed measurement mode). It is also possible to set the measurement mode on the display screen and the comparator's measurement mode independently.
Each measurement mode can be configured with frequency band limiting (bandpass setting). For instructions, please refer to the Simple Operation Manual A BAND Setting Menu.

■Measurement Mode

The following is an overview of each measurement mode.

(1) RMS (Relative Mass Value)

This displays the maximum effective value over a 0.5-second period. Measurements are repeated at 0.5-second intervals.

(2) PEAK

This displays the maximum absolute value of the time-domain waveform over a 0.5-second period. Measurements are repeated at 0.5-second intervals.

(3) MAX HOLD

This function holds and displays the maximum effective value within the measurement time. When MAX HOLD is active, the vibration display value is held, but the bar graph is not. To release the MAX hold value, press the reset key (RST) or input a set signal from the terminal block on the back.

(4) PEAK HOLD

This function holds the maximum absolute peak value within the measurement time. While peak hold is active, the vibration value is held, but the bar graph is not. To release the peak hold value, press the reset key (RST) or input a reset signal via the terminal block on the back.

■Comparison function

For each of the measurement modes described above (1) to (4), there is a manual operation mode and an automatic operation mode.

(1) Manual driving

• In the above measurement modes (1) RMS and (2) PEAK, the maximum value is repeatedly measured every 0.5 seconds as shown in the diagram below, and the maximum value is updated and displayed. At the same time, a comparison judgment is made to determine whether the value exceeds the set value. Once an NG judgment is made, the comparison output is held until it is reset. (Even if the display drops below the set value, the NG judgment will not be turned OFF unless it is reset.)

  Reset → Measure for 0.5 seconds → Display maximum value → Measure for 0.5 seconds → Update maximum value display... (End of first judgment) → Reset (Start of second judgment)...

  This involves repeated measurement and evaluation.



• In the above measurement modes (3) MAX HOLD and (4) PEAK HOLD, there is no 0.5-second measurement window as in section 1; the instantaneous value is used for sequential judgment. Once an over-limit is detected, the judgment will remain as NG until it is reset.

  Reset → MAX HOLD / PEAK HOLD (1st judgment complete) → Reset (2nd judgment start)...

• Pause, reset
  In manual operation mode, you can temporarily pause the measurement by pressing the ENT key. (There is no input function from the terminal block.)
  The word PAUS will appear on the screen. Press the ENT key again to cancel.

  To reset the unit, press the "RST" button (reset key) on the front panel or input a reset signal via the terminal block on the rear panel.

(2) Automatic operation

The measurement can be controlled by switching the GATE signal ON/OFF. (The gate signal is input via the terminal block on the rear panel.)
Similar to manual operation, once a judgment is rejected, the "NG" status is retained until it is reset. For comparison using GATE, please use the following sequence:

Reset → GATE on (measurement/judgment) → GATE off (judgment reading) → Reset (start of second judgment)...

• In the above measurement modes (1) RMS and (2) PEAK, the measured values will be as shown in the figure below depending on the timing of the GATE.

  

  - If the gate time is 0.5 seconds or less: The maximum value within the gate time will be displayed when the gate is OFF.
  - If the GATE time is 0.5 seconds or longer: The maximum value at 0.5-second intervals will be displayed sequentially.
  - The displayed value will be used for comparison and evaluation.

• In the above measurement modes (3) MAX HOLD and (4) PEAK HOLD, there is no 0.5-second measurement window like in (1) RMS and (2) PEAK; the instantaneous value is used to make a sequential judgment and the maximum value is displayed.
  Once the comparator determines something is NG, it remains ON until it is reset.

  Reset → MAX HOLD/PEAK HOLD (1st judgment complete) → Reset (2nd judgment start)...