54
BAS-SVX090B-EN
Ground Measurements
General Information and Checkout
Procedure Measurement
Expected Value
Method 1: AC voltage between shield
conductors and device chassis ground-
the voltage difference between BACnet
MS/TP device chassis ground
connections should be close to zero. If
the voltage difference is greater that 4.0
Vac, there will be marginal
communication or intermittent
communication problems. If the voltage
difference is greater that 7.0 Vac, some
devices will no longer communicate.
Measure AC voltage across the voltage
termination and confirm that only one
end of the shield conductor is tied to the
earth ground
Vac ≤ 2.0 V
Method 2: AC voltage between earth
ground and device chassis ground- the
chassis ground of the Symbio 500 needs
to be connected to earth ground by some
route.
Do not assume that the building frame is
a valid earth ground.
Measure AC voltage across the voltage
termination and confirm that only one
end of the shield conductor is tied to the
earth ground
Vac ≤ 4.0 V
(Must comply with National Electrical
Code™ and local electrical codes)
Method 3: AC voltage between case
(nominal chassis ground) and device
chassis ground connector- in this
illustration the connection appears as a
short. However, it is possible that the
chassis ground connection on the
controller may actually be connected to
the equipment metal some distance
away. Use this measurement method if
there are communication issues or input
stability problems.
Measure AC voltage across the voltage
termination. For this measurement,
confirm that only one end of the shield
conductor is tied to the earth ground.
Vac ≤ 4.0 V
(Must comply with National Electrical
Code™ and local electrical codes)
Typically, this should be Vac ≤ 1.0 V
Commissioning and Troubleshooting in Powered State
To Next Page
Loading...
