Brochure/Catalogue

Varistors
U
VDR
load
+
–
(∼)
(∼)
VDR
U
S
12
t
The functional principle of varistors is also based on
breakdown voltages (UVDR). High energies can be
dissipated, but this causes the component to aging.
Therefore, the breakdown voltage is reduced over time and
the leakage current is increased.
Advantage:
• Uncritical dimensioning
• Suitable for DC and AC voltage
• Slightly extended switch off process
Disadvantage:
• Complex and expensive with increasing power
• Low effect on the service life of the contact
RC modules
U
RC
load
+
–
(∼)
(∼)
R
C
U
S
12
t
With RC modules, voltage peaks are compensated via
a capacitor. Thanks to its special characteristics during
charging and discharging the interference pulses are already
ltered out during the voltage rise and not only when the
breakdown voltage (URC) is reached.
Advantage:
• Suitable for DC and AC voltage
• Slightly extended switch off process
Disadvantage:
• Exact dimensioning required
• High inrush current
• Low effect on the service life of the contact
W
Technical appendix/Glossary
W.132737920000
Protective circuits for outputs