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External Connection
Measures Against Voltages
When connecting a load which may generate a surge voltage or
current, for example an inductive load (relay coil) or incandescent
lamp, to one-shot output lines, suitable protection measures are
required to prevent damage to the output stage or a malfunction due
to noise. Instantaneously interrupting current flowing through a
coil including a relay causes the sudden generation of a high-
voltage pulse. If its voltage exceeds the withstand voltage of the
transistor, the performance of the transistor may be degraded or it
may be damaged. To prevent this, be sure to connect a surge
absorption element when driving an inductive load including a relay
coil. Examples of measures against surge voltages are as shown in
the Figure 3.14. below.
Figure 3.14. Samples of Surge Voltage Protection
Note!
The protection circuit will not be effective unless it is installed less
than 50cm from the load and contact.
31
CNT24-4(PCI)
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