Contact Protection Measures - WIKA GDM-63 Betriebsanleitung

5. Commissioning, operation
Overcurrent protectors
The instruments do not provide for incorporated overcurrent protectors. Should protec-
tors be required, the following values in accordance with EN 60947-5-1 are to be
recommended.
Voltage 24 V: 2 A
■
Voltage 250 V: 1 A
■
EN

5.2.2 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 following 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
Inductive load with AC voltage
With AC voltage two protective measures are possible:
Example:
Contact protection measure
with voltage-dependent
VDR resistor
Example:
Contact protection
measure with RC element
14
Contact
Diode
WIKA operating instructions gas density monitor model GDM-63
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