User's Manual

FIREMASTER IV " MillenniumThree " radio shooting system User’s manual
4.8 Connections
4.8.1 Firing lines
Each section of the RX48 Remote Unit is provided with 24 couples of binding
posts to connect a total of 48 independent firing lines.
Each line is powered by the internal batteries of the Unit itself. The batteries for
the lines supply are exclusively dedicated to this duty (all other circuits are
supplied with a separate battery). All Units are supplied with two 12V batteries
connected in series for a total of 24V available to the fire lines.
Being these batteries of the lead-acid type with gel immobilized electrolyte, the
available peak current to each line (during short periods) can be very high (up to
10A peak).
Using standard igniters with a resistance of 1.5 to 2 ohm, it will possible to
connect no more than 10 devices IN SERIES and no more than 8 IN
PARALLEL (the latter configuration IS NOT SUGGESTED anyway).
Using non-standard igniters, it will be possible to calculate approximately the
maximum number of devices to be connected IN SERIES, taking into account
for the resistance value and the minimum firing current (specifications supplied
by the manufacturer). Proceed first calculating the maximum allowable
resistance on a firing line Rmax given by:
R
Vfire
in
Rlinemax
Im
=−
where: Vfire=24V
Imin=minimum fire current of each (in amperes, as declared by the
manufacturer).
Rline=resistance (in OHM) of the connection wires to the Unit.
It will be then calculated the maximum number of igniters Nmax to be
connected IN SERIES to a single line using the following equation:
N
R
Rign
max
max
=−2
where: Rmax is the value obtained from the previous calculation
Rign is the resistance value of a single igniter
Eg.: using a standard Unit with a 24V battery, a connection line of 25 meters
made of copper wire (section 0,22mm
2
), daveyfire X
2
igniters with 5meter of
connection cables, it will be obtained:
Vfire=24V, I min=0.8A, Rline=3ohm (about)
R ohmmax
.
=−=
24
08
327
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