©
National Instruments Corp.
9
cFP-RLY-423
250 V
rms
1
. Safety standards (such as those published by UL
and IEC) require the use of double insulation between hazardous
voltages and any human-accessible parts or circuits.
Never
try to use any isolation product between human-accessible
parts (such as DIN rails or monitoring stations) and circuits that
can be at hazardous potentials under normal conditions, unless the
product is specifically designed for such an application, as is the
cFP-RLY-423.
Even though the cFP-RLY-423 is designed to handle applications
with hazardous potentials, follow these guidelines to ensure a safe
total system:
•
The cFP-RLY-423 has a safety isolation barrier between the
I/O channels and the inter-module communication bus. There
is no isolation between channels unless otherwise noted. If any
of the channels on a module are wired at a hazardous potential,
make sure that all other devices or circuits connected to that
module are properly insulated from human contact.
•
Do
not
share the external supply voltages (the V and C
terminals) with other devices (including other FieldPoint
devices), unless those devices are isolated from human contact.
•
You
must
connect the protective earth (PE) ground terminal
on the cFP-BP-
x
backplane to the system safety ground. The
backplane PE ground terminal has the following symbol
stamped beside it:
. Connect the backplane PE ground
terminal to the system safety ground using 14 AWG (1.6 mm)
wire with a ring lug. Use the 5/16 in. panhead screw shipped
with the backplane to secure the ring lug to the backplane
PE ground terminal.
•
As with any hazardous voltage wiring, make sure that all
wiring and connections meet applicable electrical codes
and commonsense practices. Mount backplanes in an area,
position, or cabinet that prevents accidental or unauthorized
access to wiring that carries hazardous voltages.
•
The isolation of the cFP-RLY-423 is certified as
double-insulated for working voltages of 250 V
rms
. Do
not
use
the cFP-RLY-423 as the only isolating barrier between human
contact and working voltages of more than 250 V
rms
.
1
Working voltage
is defined as the signal voltage plus the common-mode voltage.
Common-mode voltage
is the voltage of the module with respect to ground.
