MMF VM22, Инструкция по эксплуатации

Страница: 21 / 29

Additionally, clock inaccuracy can be corrected. This can be done using the setting
at “Cal.” in ppm (parts per million). The clock frequency can be increased with posi -
tive values and decreased with negative. The sign changes to minus at +254 ppm.
Example: The clock is 5 seconds slow. There are 24 * 60 * 60 s = 86400 seconds in
a day. The difference amounts to 5 s / 86400 s = 58 * 10
-6
= 58 ppm. The adjustable
value is -58 ppm.
To exit the menu press OK followed by F2 repeatedly.
10. Calibration
The VM22 comes with with a factory calibration, which is traceable to the reference
standard of the Physikalisch-Technischen Bundesanstalt (PTB). The calibration is
only valid with the supplied vibration transducer. The serial number of the instru-
ment and the transducer are stated on the calibration certificate. The month and year
of the factory calibration are displayed when the instrument is switched on (cf. 5 on
page 6).
The value set upon calibration is the transducer sensitivity in mV/ms
-2 .
This can be viewed in the calibration menu. Remove the sensor from the VMID and
open the main menu by pressing F2. From the main menu scroll down using F1 until
you reach the menu option “Sensor calibration” and select OK. Within this sub-
menu select “By entering sensitivity”. The displayed value is the sensor's calibrated
sensitivity. (22). It should not be changed, unless a new calibration is being carried
out. Press OK followed by F2 repeatedly to exit the menu.
19
Figure 21: Time and Date
Figure 22: Transducer sensitivity