Chapter 1
Routing Signals with Your NI 2565
1-2
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National Instruments Corporation
High Voltage
The NI 2565 general purpose switch card is rated for reinforced insulation,
250 V, Cat. II. This classification provides safety insulation from any
terminal to any other accessible part on the card. The switch card is rated
for basic insulation, 250 V Cat. II, from any screw terminal connection to
any other screw terminal connection.
Insulation coordination can be achieved only if transient overvoltages are
controlled to specified levels. Refer to the
for more information
about Categories I and II overvoltage specifications.
Caution
For additional safety, if you will be switching power lines or high voltage, place an
F7A 250 V in-line fuse before the switch card.
Always disconnect the screw terminal plug from the front connector before
removing the module from the PXI chassis.
Before applying high voltage to the module, always tighten the four captive screws
to provide a ground connection from the module to the chassis.
Warning
Do not exceed 250 V channel-to-channel or channel-to-ground. Any connections
that exceed the maximum settings for the NI 2565 can result in an electrical shock
hazard and damage to the switch card and any or all of the boards connected to
the PXI backplane. National Instruments is NOT liable for any damages or
injuries resulting from exceeding maximum voltage ratings. Refer to Appendix A,
, for information.
Contact Protection
Caution
When inductive loads are connected to the relays, a large counter electromotive
force may occur at relay switching time due to the energy stored in the inductive
load. These flyback voltages can severely damage the relay contacts and greatly
shorten the life of the relay.
It is best to limit flyback voltages at your inductive load by installing a flyback
diode for DC loads or a varistor for AC loads. Refer to Appendix B,
, for more information on flyback voltage protection.
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