MMF VM24, Инструкция по эксплуатации

Страница: 13 / 34

4.4. Shut-off Timer
The VM24 has a shut-off timer to help prolong the battery operating life. To set the
shut-off timer, open the main menu by pressing F3. Scroll down into the sub-menu
'Instrument Settings' by pressing▼and OK, and within this sub-menu select the
menu option “Shut off Timer”. Press keys ▼▲ to select the timer duration from the
options 1, 5, 15 and 60 minutes or to deactivate the timer select ('none'). The switch
off timer starts to run after the last press of a button. If any button is pressed then
the timer restarts and counts down again according to the duration selected.
5. Preparation of Measuring Points
5.1. General Information on Measurement Point Choice
When monitoring machines it is important to take measurements under the same op-
erating conditions, at the same measurement point. Choosing the suitable measure-
ment point is therefore decisive.
Where possible, qualified staff experienced in machine monitoring should be called
upon.
It is generally advisable to record machine vibrations near to their source. This helps
to reduce distortion of the measuring signal to a minimum when it is being carried
through transmission parts. Suitable measurement points include rigid machine
components such as bearing housings or gearboxes.
Light or mechanically flexible machine components such as cladding and casing are
unsuitable for the measurement of vibrations.
5.2. ISO 10816-1 Recommendations
The standard ISO 10816-1 recommends bearing housings or their immediate sur-
roundings as preferred measuring location points for the measurement of machine
vibrations (Figures 13, 14, 15 and 16).
For the purpose of monitoring a machine it is normally sufficient to take measure-
ments in only one direction, either vertically or horizontally.
On machines with horizontal shafts and rigid foundations the largest vibration am-
plitudes occur horizontally. With flexible foundations, strong vertical components
also arise.
For the purpose of acceptance tests, measurement values are to be taken from all
bearing point locations at the center of the bearing and in all three directions (verti-
cal, horizontal and axial).
The following illustrations give a few examples of suitable measurement point loca-
tions..
11
Figure 12: Shut-off time