NI 9472/9474
14
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I/O Protection
The NI 9472/9474 is short-circ
u
it proof in accordance with
IEC 1131-2 and provides overc
u
rrent protection.
Understanding Short-Circuit-Proof Devices
Each channel on the NI 9472/9474 has circ
u
itry that protects it
from c
u
rrent s
u
rges res
u
lting from short circ
u
its. Whether the
mod
u
le s
u
ffers damage from these overc
u
rrent conditions depends
on the following factors:
•
The amo
u
nt of c
u
rrent thro
u
gh the channel
•
The amo
u
nt of time the c
u
rrent is above the c
u
rrent limit
•
The freq
u
ency of the c
u
rrent s
u
rges
When the amo
u
nt of c
u
rrent thro
u
gh the DO terminal or pin is
greater than 13 A, the channel trips and goes into an overc
u
rrent
state. In an overc
u
rrent state, the channel t
u
rns off and the mod
u
le
is not damaged. If the c
u
rrent thro
u
gh DO is between 6 A and 13 A,
the state of the channel is indeterminate and depends on factors
s
u
ch as the c
u
rrent level, the temperat
u
re, and the power s
u
pply.
Higher inr
u
sh c
u
rrents that exist for less than the trip time do not
trip the protection circ
u
itry. Refer to the
Specifications
section for
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