Shield Voltage (Switch Position 5); About Nmea 2000 Shield Voltage - Maretron N2KMeter User Manual

10 Shield Voltage (Switch Position 5)

The N2KMeter measures live, minimum, and maximum DC shield voltage (between shield and
NET-C).
Display
Thresholds
High Voltage Fault
High Voltage Warning
Low Voltage Warning
Low Voltage Fault
10.1 About NMEA 2000
®
The NMEA 2000 specification requires that the shield and NET-C be connected together at the
power supply. This has the following effects:
 A correctly connected shield has no current flow in it and is at the same voltage (grounded
power supply NET-C) throughout the system.
 Current flow in NET-C causes a voltage rise in NET-C
 Rising NET-C voltage causes an apparent negative shift in the shield voltage when
measured relative to NET-C
 Since the maximum allowable voltage drop in NET-C is 2.5V, the negative shift in shield
voltage is between -2.5V and 0V
Systems connected in accordance with the NMEA 2000
shield voltage between -2.5V and 0V.
Revision 1.3
What it means
Current shield voltage is -1.4V.
The minimum shield voltage recorded
since the N2KMeter was plugged in
or reset is -1.5V.
The maximum shield voltage
recorded since the N2KMeter was
plugged in or reset is -1.2V.
1.0V
0.3V
-2.0V
-2.5V
®
Shield Voltage
®
installation guidelines have a "normal"
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