MKS HPS 945 Series, Operation And Maintenance Manual

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14
Digital Pirani vacuum Sensor System
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 may 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 are calculated by the equations,
C = I
2
/(1 x 10
7
) and R = E/10I
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
Ω
and C
min
= 1.0 x 10 -9 F.
Pin Description
1 Set point relay 1 - normally closed contact
2 Set point relay 1 - normally open contact
3 Set point relay 2 - common
4 Not used
5 Analog output voltage (+)
6 Set point relay 1 - common
7 Set point relay 2 - normally closed contact
8 Set point relay 2 - normally open contact
9 Analog output voltage (-)
9-pin Accessory port
1 5
9
6
E
R
C