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11041781.04 01/2020 EN/DE
Pressure gauge with reed contact model 851-A, for Ex areas
EN
5.3 Contact protection measures
Mechanical contacts must not exceed the specified electrical
values for switching current, switching voltage and switching
power independent of each other, not even for a short time only.
For capacitive or inductive loads we recommend one of the follow-
ing protective circuits:
Inductive load with DC voltage
With DC voltage the contact protection can be achieved via a
free-wheeling diode, connected in parallel to the load. The polarity
of the diode must be arranged so that it closes when the operating
voltage is on.
Example:
Contact protection
measure with
free-wheeling diode
Contact
Diode Load
5. Commissioning, operation
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