Secondary Protection
Secondary Protection Reference Circuit
Figure 3.38 also shows an example of an interface design for a secondary protector. The
P3203AB SIDACtor device is used because the peak off-state voltage (VDRM) is greater
than the potential of a Type B ringer signal superimposed on the POTS (plain old telephone
service) battery.
150 VRMSꢀꢁ2 + 56.6 VPK = 268.8 VPK
Coordination between the station protector and the secondary protector occurs due to the
line impedance between the two devices. The line impedance helps ensure that the primary
protector will begin to conduct while the secondary protector limits any of the let-through
voltage to within the VS rating of the SIDACtor device.
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© 2002 Teccor Electronics
SIDACtor Data Book and Design Guide
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