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aTCA-80302PA/PD
7.1.4 AC PEM Connector PIN Assignment
7.2 DC PEM
Two pluggable redundant DC Power Entry Modules (PEM) are located at the rear
top side of the Shelf. Each PEM provides power terminals for 35A power feed.
Each power feed consists of a –48 VDC cable and its corresponding return cable.
The feed is protected by a 35 A fused switch.
The power filtering consists of filtered power terminals and a discrete line-filter for
each power branch. The input voltage range for the Shelf is from -40VDC to -
72VDC.In each power feed, voltage measurement is implemented, by means of a
dedicated voltage monitor device.
The PEM (together with all shelf related FRUs) are protected against wrong polarity
up to +57 VDC, but it does not block wrong polarity voltage being applied to shelf
related FRUs and to Zone 1 power wiring of payload slots.
Suppressor diodes are included in the feed chain that provide protection against a
K.20 pulse of 500 V being applied to its input (K.20 surge pulse, "Basic level",
Table 7, pulse type 7.3, 500 V applied to -48 V and RTN branches at the same time
against shelf ground) so that PEM itself and other shelf related FRUs can sustain
this level of pulse.
