15. Calibration
The VM31 is supplied with a factory calibration. In this way it is assured that the in-
strument measures accurately if a calibrated transducer is connected and its sensitiv-
ity entered (see section 10.1). Month and year of the last calibration are shown on
the start screen (Figure 50).
The standard ISO 8041 lays down the requirements of electrical and mechanical cal-
ibration of human vibration meters.
Figure 53 shows the connections for calibrating the VM31 with electrical signals.
The signal generator needs to be connected via the shown R-C combination to the
inputs X/Y/Z and A. The 4.7 kΩ resistor serves as a sink for the IEPE constant cur-
rents. The 1000 µF capacitor keeps the resulting DC voltage drop away from the
generator. The electrolytic capacitor must be rated for at least 25 V. Please make
sure that the generator output can handle the resulting load of approx. 1 kΩ.
Plug for X/Y/Z:
Binder
711 series, 4 pins, order no. 99-0079-100-04
Plug for A:
Binder
711 series, 8 pins, order no. 99-0479-100-08
The maximum input voltage without overload indication is ± 1150 mV.
32
Figure 53: Connections for electrical calibration
GND
X
Y
Z
+
4k7
1000µ
Generator
GND
X
+
4k7
1000µ
GND
Y
+
4k7
1000µ
GND
Z
+
4k7
1000µ
GND
A
GND
A
