NI USB-9472 User Guide and Specifications
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Figure 10.
Assembled High Voltage Screw Terminal Backshell
I/O Protection
The NI USB-9472 is short-circuit-proof in accordance with IEC 1131-2
and provides overcurrent protection.
Understanding Short-Circuit-Proof Devices
Each channel on the NI USB-9472 has circuitry that protects it from current
surges resulting from short circuits. Whether the module suffers damage
from these overcurrent conditions depends on the following factors:
•
The amount of current through the channel
•
The amount of time the current is above the current limit
•
The frequency of the current surges
When the amount of current through the DO terminal or pin is greater than
the guaranteed trip current for the module, the channel trips and goes into
an overcurrent state. In an overcurrent state, the channel turns off and the
module is not damaged. If the current through DO is higher than the
minimum possible trip current and lower than the guaranteed trip current,
the state of the channel is indeterminate and depends on factors such as the
current level, the temperature, and the power supply.
To prevent false tripping, higher inrush currents that exist for less than the
trip time do not trip the protection circuitry. Refer to the
section for more information about the maximum continuous output
current, trip current, and trip time. You also can refer to the IEC 1131-2
standard for more information about short-circuit-proof devices.
Tip
Because the NI USB-9472 includes internal flyback diodes, you do not need to add
external diodes when connecting to switching energy storing devices.
