National Instruments cFP-PWM-520, FP-PWM-520 Overcurrent Protection, Power Supplies and Overcurrent Conditions

• Disconnect the external power supply from the

[c]FP-PWM-520.

• Remove the [c]FP-PWM-520 from the terminal base or

backplane.

• Power off the network module connected to the

[c]FP-PWM-520.

Normal operation can resume after you correct the short-circuit

condition.

Overcurrent Protection

Each output channel on the [c]FP-PWM-520 has circuitry that

protects it from current surges resulting from short circuits.

Whether the module suffers damage from 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 current surges

If the level of current through the output terminal is higher 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 level of current through

the output terminal 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.

Inrush currents that exist for less than the trip time do not trip the

protection circuitry. Refer to the Specifications section for more

information about the maximum continuous output current, trip

current, and trip time.

Power Supplies and Overcurrent Conditions

If a short circuit occurs, the current through an output terminal can

exceed the current rating for the power supply and the maximum

continuous current for the [c]FP-PWM-520.

If the power supply you are using with the [c]FP-PWM-520 cannot

supply more than the guaranteed trip current, the module may be

damaged if a short circuit occurs.