National Instruments 1191 User Manual - Contact Protection
Chapter 2
Using the SCXI-119X
SCXI-1190/1191/1192 User Manual
2-4
ni.com
SCXI backplane. National Instruments is
not
liable for any damages or injuries resulting
from exceeding maximum voltage ratings. Refer to Appendix A,
, for
specific information.
Caution
Always disconnect all signals from the front connectors and power off the SCXI
chassis before removing the SCXI-119
X
from the chassis. Observe electrostatic discharge
handling precautions during and after removal of the module, or when connecting and
disconnecting signals on the front panel.
Contact Protection
Caution
The contacts of the relays are rated for a life of 5
×
10
6
mechanical operations
when operated with no signal or a very small signal present. When high-power loads are
switched, arcing can occur across the relay contacts that will reduce their useful life. See
Appendix A,
, for lifetime ratings for each module. If your setup allows, it is
always best to turn off the input signals connected to the switch module during the
switching operation to avoid contact arcing within the switch. Switching large inductive
loads can also cause contact arcing. In such instances, install a flyback diode or varistor
across the inductance to protect the switch.