Protecting Inductive Loads - National Instruments NI Vision CVS-1456 User Manual

Chapter 3 Digital I/O Functionality

Protecting Inductive Loads

NI CVS-1450 Series User Manual
When an inductive load, such as a relay or solenoid, is connected to an
output, a large counter-electromotive force may occur at switching time
due to energy stored in the inductive load. This flyback voltage can damage
the outputs and the power supply.
To limit flyback voltages at the inductive load, install a flyback diode across
the load. Mount the flyback diode as close to the load as possible. Use
this protection method if you connect any of the isolated outputs on the
NI CVS-1450 device to an inductive load.
Figure 3-7 shows an example of using an external flyback diode to protect
inductive loads.
V
cc
NI CVS-1450 device
Figure 3-7. Example of Using an External Flyback Diode for Inductive Loads
Digital
Output
3-14
V
iso
Load
C
iso
External
Flyback
Diode for
Inductive Loads
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