8. Connecting the transducers
17
On the measuring instrument this gives the following channel assignment :
8.3
Potential separation
When organizing a properly functioning measuring setup it is very important to
ensure that no equalizing current can flow between sensors, power supply, and
peripherals. All points must therefore lie at the same potential and / or any une-
qual potentials must be electrically isolated.
The 2 inputs on version 2490-2 are electrically isolated by means of photovoltaic
relays and a potential difference of maximum 50 VDC or 60 VAC is permissible
between them. Sensors combined within one connector and sensors with their
own power supply, however, are electrically interconnected and must therefore
be operated in isolation. The voltage at the measuring inputs themselves must
not exceed 5 volts (between B, C, D, A and - ).
The power supply is isolated by the mains adapter or by a DC/DC converter
(OA2490A-R02U or ZA2690-UK). Data and trigger cables are equipped with
optocouplers. If analog output cables are not electrically isolated the recording
device or the sensors must be zero-potential.
