Damage/Threshold question

Reading through the damage section of FT last night and ,after reading
where
Thresholds are made against each system,a question arose as to whether I
am
playing it correctly or not.

A Federation DD with 10dp (3/3/2/2) has suffered 8dp damage from Romulan
Wave Gun,so gets 3 Threshold checks.I know I check for each system--the
DD
has 3 Beam2 batteries.So is EACH beam battery considered a system (roll
for
each one for Threshold,3 rolls total) OR are all 3 beam batteries
considered
as ONE system (only 1 Threshold check die roll?)

I have been playing it using the first method described,based on context
of
how systems are described elsewhere in the rules (FC ,Minelayers,and
ship
design for example.) Just want to make sure I am doing it the right way
according to the rules.

BTW,if anyone is interested I can write up both the scenario and an AAR
after playing it--another of my solo designs for Trek universe.Just let
me
know.........thanks.

Mark Drake