Potential Separation; Display And Keypad; Display - Ahlborn ALMEMO 2490-2 Operating Instructions Manual

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 un-
equal potentials must be electrically isolated.
sensor
M1
M0
The 2 inputs on version 2490-2 are electrically isolated by means of photovol-
taic relays and a potential difference of maximum 50 VDC or 60 VAC is per-
missible 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 them-
selves must not exceed 5 volts (between B, C, D, A and - ).
The power supply is isolated by the transformer in the mains adapter or by a
DC/DC converter (OA2490-U 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.

9. DISPLAY AND KEYPAD

9.1 Display

The display (5) on the ALMEMO
arrangement; the main field comprises 5x 7-segment digits (e) plus 2x 16-seg-
ment digits (d) for depicting the measured value;,the function field comprises
41/2x 7-segment digits (b) for depicting various measuring functions (a); there
are also 4 arrows (f) for depicting the operating status.
Function field
Main field
U+
ADC
U-
® 2490 measuring instrument is a 2-row LCD
uC
Power supply
ALMEMO
Potential separation
Data cable
DC
AC
230V≈
DC
DC
10..30V=
® 2490 17