National Instruments CFP-CB-2 用户手册
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13
cFP-CB-1/2/3/4
Isolation and Safety Guidelines
Caution
Read the following information before
attempting to connect the cFP-CB-x to any circuits that
may contain hazardous voltages.
may contain hazardous voltages.
This section describes the isolation of the cFP-CB-x and its
compliance with international safety standards. The field wiring
connections are isolated from the backplane and the inter-module
communication bus. The isolation is provided by the module,
which has optical and galvanic isolation barriers designed and
tested to protect against transient fault voltages of up to 2,300 V
compliance with international safety standards. The field wiring
connections are isolated from the backplane and the inter-module
communication bus. The isolation is provided by the module,
which has optical and galvanic isolation barriers designed and
tested to protect against transient fault voltages of up to 2,300 V
rms
.
The cFP-CB-x provides double insulation (compliant with
IEC 61010-1) for working voltages of 250 V
IEC 61010-1) for working voltages of 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.
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-CB-x.
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-CB-x.
Even though the cFP-CB-x is designed to handle applications with
hazardous potentials, follow these guidelines to ensure a safe total
system:
hazardous potentials, follow these guidelines to ensure a safe total
system:
•
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.
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.
terminals) with other devices (including other FieldPoint
devices), unless those devices are isolated from human contact.
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.
Common-mode voltage is the voltage of the module with respect to ground.