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LS4808 / LS4816 | 8 / 16 CHANNEL SPEAKER LINE SURVEILLANCE
Notes On Speaker Line Impedance
In reality, impedance of a speaker circuit consists of Resistance (normally cable) and Capacitance and Inductance
(speaker coils).
Z = R + Indu Capacitance
Using a multimeter (pure resistance measurement) to measure a speaker circuit is not the accurate tool to determine the
value to calculate the total load of the line, which they are not capable to measure the Capacitance or Inductance of
cable and speaker coils.
In circuit with branching, a break at point would not trigger an ‘open circuit’ alarm, and a short at point would not
trigger ‘short circuit’ indication as these still exist some impedance due to cable resistance.
LS4808 / 4816 has unique way to detect faults, there by using basic mode, creating an impedance limit range and for
more sensitive detection, set the unit to ‘advance’ mode.
A
B
B
A
A
Impedance
meter
▲
▲
----
▲
Ø
▲
Branch
R
L / C
L / C
VC
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