Velocity Operation Manual
www.velocitydetection.com
76
Earth Trouble
An EARTH fault indicates that something is shorting to earth (usually through the cable screen). Disconnect the earth screens one at a
time to determine the problem line. (Note: connecting other equipment, e.g. a mains powered laptop, to the panel can give an earth
fault)
The earth fault message will indicate if it is a Positive or Negative voltage shorting to earth.
NOTE: The NAC circuits are reverse polarity when they are not running. A ground fault to the NAC + terminal would produce a negative
earth fault message. Similarly, a A ground fault to the NAC - terminal would produce a positive earth fault message.
Earth Positive Fault
Most Earth faults occur on the field
wiring. As a first check, disconnect
field wiring from the Velocity Panel. If
no earth fault is reported then fault is
on the field wiring. Locate the fault
by reconnecting one field wiring
circuit at a time until the earth fault
reports, then sub divide the “bad
circuit”. Look for a cable screen
shorting to loop +ve.
Earth Negative Fault
Use the same method as above, but
look for shorts to –ve.
CPU Trouble
A CPU fault is an abnormal microprocessor running condition due to various unexpected phenomena.
This will result in the panel attempting to correct itself. Should this fault occur, the CPU Trouble LED, Common Trouble LED, Common
Trouble relays and internal Trouble buzzer will be constantly active. A CPU trouble indication can be cleared by pressing the CPU reset
button located on the TRM PCB. If the trouble condition does not clear please consult your distributor.
System Fault Reset Button
