Application Information; General Application Information; Slowing Down Motion; Apparent Direction Of Movement - TESTO 477 Mode D'emploi

7 Application information

Pos: 32 /TD/Überschriften/Anwendungshinweise 477 @ 4\mod_1251901467301_79.doc @ 48178 @ 1
7 Application information
Pos: 33 /TD/Produkt verwenden/testo 477/allgemeine Anwendungshinweise 477 @ 4\mod_1251878000012_79.doc @ 48147 @ 23333
7.1.

General application information

7.1.1.

Slowing down motion

As discussed, the primary use of the testo 477 is to slow down or
"freeze" the apparent motion of moving objects. This allows you to
analyse their run-time performances safely and easily.
To make an object appear to move in slow motion, you need to
strobe it at a rate slightly above or slightly below its actual speed
(or any harmonic of its speed as discussed below). Simply use the
four buttons until you achieve the desired apparent movement.
Helpful Hints:
The speed at which the object appears to move can be determined
by subtracting the flash rate from the object's actual rate.
Example:
If an object is rotating at 1,000 RPM and you strobe it at a rate of
1,005 flashes per minute (FPM), the object will appear to be
moving at a rate of 5 RPM.
Speed = Actual Rate - Flash Rate
= 1,000 PRM - 1,005 PRM
= 5 RPM
7.1.2.

Apparent direction of movement

The direction (clockwise vs. counterclockwise or forward vs.
backward) at which the object appears to move is determined by
the flash rate, the object's actual direction of movement and the
orientation of the stroboscopic beam to the object.
Example: Assume you wish to visibly slow down the movement of a
fan which is rotating clockwise at 1,000 RPM.
Case 1: If you stand in front of it and strobe it at a rate of 1,005
flashes per minute (FPM), the object will appear to be moving at a
rate of 5 RPM in a counterclockwise direction.
Case 2: If you stand in front of it and strobe it at a rate of 995 FPM,
it will appear to move at a rate of 5 RPM in a clockwise direction.
Case 3: If you stand behind it and strobe it at a rate of 1,005 FPM,
it will appear to move in a clockwise direction at a rate of 5 RPM.
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