Measurement Computing 6K-ERB08 - Manual (Page 23)

6K-ERB08 User's Guide Functional Details
Relay contact protection circuit for inductive loads
When you connect an inductive load to a relay, energy stored in the inductive load can induce a large voltage
surge when you switch the relay. This voltage can severely damage the relay contacts. To limit the voltage
surge across the inductive load, install a kickback diode across the DC load. Refer to the contact protection
circuit in
. For AC loads, install a metal oxide varistor (MOV). Figure 3-5
Figure 3-5. Relay contact protection circuit
C
V
Inductive
Load
Kickback
Diode
NC
+
-
NO
Relay
3-4