2.11 General Note about Relays and Inductive Loads

 

High voltage transients may occur when switching inductive loads such as some contactors or solenoid valves. Through the internal contacts, these transients may introduce disturbances which could affect the performance of the instrument.

 

For this type of load it is recommended that a ‘snubber’ is connected across the normally open contact of the relay switching the load. The snubber recommended consists of a series connected resistor/capacitor (typically 15nF/100Ω). A snubber will also prolong the life of the relay contacts.

 

 

 

WARNING

When the relay contact is open or it is connected to a high impedance load, the snubber passes a current (typically 0.6mA at 100Vac and 1.2mA at 230Vac). You must ensure that this current will not hold on low power electrical loads. If the load is of this type the snubber should not be connected.