MKS HPS 903 Series, Operation And Maintenance Manual

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11 Cold Cathode Ionization Vacuum Sensor
Relay Inductive Loads and Arc Suppression
If the set point relay is used to switch inductive loads, e.g. solenoids, relays,
transformers, etc., the arcing of the relay contacts might interfere with
controller operation or reduce relay contact life. Therefore an arc suppression
network, shown schematically below, is recommended. The values of the
capacitance
C and the resistance R can be calculated by the equations,
C = I
2
/(1 x 10
7
) and R = E/I
a
where,
C is in farads
R is in ohms
I is DC or AC
peak
load current in amperes
E is DC or AC
peak
source voltage in volts
a = 1 + (50/E).
Note that,
R
min
= 0.5 W and C
min
= 1.0 x 10
-9
F.
Relay arc suppression network