Why does a ViB think in g?

The sensor is an accelerometer. It feels the change of speed, so its range and trigger are in g.

Where is acceleration biggest?

At the ends of the swing, where the speed flips.

Which way does the a arrow point?

Back toward rest, every time. That is what makes the ground swing back.

Concept4 min3 of 5 in the seriesVibration monitoring

Where we areLast page: how fast. This page: how the speed changes.

How the speed is changing.

a · g

Acceleration is how quickly the ground's speed is changing. We write it a and measure it in g.

0.10 mmDisplacement

0 mm/sVelocity

0.16 gAcceleration

The a arrow always points back toward rest, biggest where the particle stops.

t = 13 ms of 100 ms80× slower than real time

1
Your call first
Where is the push on the particle biggest?
Tap one, then watch.
It stops before it turns
At the end of the swing the speed is zero, but it is about to flip. Flipping the speed is the biggest change there is.
2
The turn is the biggest push
Look at the a arrow. It is longest at the ends and points at rest. At 0.16 g it is like the shove of a ute pulling away hard.
3
It always points at rest
A senses this push, not the distance and not the speed. That is why its is set in .

The relation

How the four connect

One motion, four numbers. Turn the dial and watch the sums.

Frequency · 20 Hz

0.10 mmDisplacement

13 mm/sVelocity

0.16 gAcceleration · 50 ms per cycle

Displacement0.10 mm
× 2πf at 20 Hz0.10 mm × 126 = 13 mm/s
Velocity13 mm/s
× 2πf at 20 Hz13 mm/s × 126 = 0.16 g
Acceleration0.16 g

The general rule

v = 2πf · x, a = 2πf · v

The general rule: peak push is 2πf times peak speed. Written in g: divide mm/s² by 9806.65.

In the field

Would this pass?

The unit stores a trigger as a share of its range: 5% of 40 g is 2 g, about the jolt of a car door slamming. Until you name a frequency, that is not a mm/s answer.

The card turns this page's motion into a peak speed and checks it against a limit. Move the frequency and the same g becomes a different speed.

Over the limit

0.10 mmDisplacement

13 mm/sVelocity

0.16 gAcceleration

Frequency · 20 Hz

0.10 mmDisplacement

13 mm/sVelocity

0.16 gAcceleration · 50 ms per cycle

An indicative limit. Your project's standard sets the real one.

Quick check