Engineering tools

Field calculators, from our own toolbox.

Tools we built for our own commissioning work and use on site.

Tool 01

Charge injection calculator

Check a vibration monitor without shaking the sensor. A piezoelectric accelerometer delivers a charge (pC) proportional to acceleration, so with a charge generator (Coulomb simulator) you inject that charge straight into the monitor input at the 1X frequency of the machine. This tool converts a vibration level at running speed into the peak charge to inject, and an injected charge back into the reading you should see.

Level and speed

Enter the vibration level to simulate (an alarm or trip setpoint, as displacement or velocity) and the running speed of the machine.

Sensor sensitivity

Enter the sensitivity of the accelerometer in pC/g, from its datasheet or calibration sheet.

Inject and compare

Set the charge generator to the pC and the frequency shown in the result, then compare the monitor reading. Monitors with a tracking filter or keyphasor also need a speed signal: simulate it at RPM ÷ divisor.

A

Vibration level → charge to inject

pC/g
From the datasheet
Inject
Charge input — pC Speed input
Peak value. pC = velocity × 2π × f × sensitivity / 9810
B

Injected charge → expected reading

pC
pC/g
From the datasheet
Expected
Monitor reads — mil Charge input Speed input
velocity = pC × 9810 / (2π × f × sensitivity) · displacement = velocity / (2π × f)
Running speed and 1X: unbalance shows up once per revolution, so the charge is injected at the 1X frequency: RPM ÷ 60 Hz. That is the frequency to set on the charge generator. Enter the speed in RPM, or switch to Hz to enter the frequency of the speed signal instead.
Speed signal divisor (RPM : Hz): how many RPM one Hz of the speed pickup signal represents: 60 ÷ teeth on the speed wheel, times the gear ratio if the wheel sits on another shaft. A 60-tooth wheel gives 1 (3000 RPM = 3000 Hz), 47 teeth gives 1.277 (9000 RPM = 7050 Hz), a one-pulse-per-rev keyphasor gives 60 (3000 RPM = 50 Hz). Only matters when you simulate the speed input of the monitor as well, or enter the speed as a signal frequency. The 1X frequency for the charge generator stays RPM ÷ 60.
Charge output: the result is peak pC (not peak-to-peak), the standard for piezoelectric accelerometer charge injection calibration.
pC = (velocity [mm/s] × 2π × f [Hz] × sensitivity [pC/g]) / 9810
Unit conversions:
1 mil = 0.0254 mm = 25.4 μm | RPM ÷ 60 = Hz
Displacement ↔ velocity: v = d × 2πf
Peak ↔ peak-to-peak: multiply or divide by 2
Restricted

Tools for authorised users

Two more tools are built on OEM data: the LM2500+G4 4B bearing HP recoup orifice tool and the LM5000 VG schedule verification tool. They are available to persons authorised by the OEM, with a personal login.

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