Advanced MX-4200V, Руководство пользователя

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5.2.1 Detector Loop Lengths
With the above cables, loops can be up to 2Km in length. However, care must be taken when designing the
system to take into account the maximum loop loading. The voltage drop (load current x cable resistance) over
the cable always needs to be taken into account to ensure the devices receive an adequate supply voltage. The
following table gives recommendations for a loop. (It may be possible to extend the lengths where the devices
are distributed evenly
– refer to the VEGA device data sheets and loop calculator for further information on
calculating loop loading, cable cross sectional area and loop distance).
Maximum Circuit
Impedance
72Ω
Circuit
Loading Max. Circuit
Impedance
Loop Cable Distance (M)
1.0mm
2
1.5mm
2
2.5mm
2
Maximum Capacitance
(Core-Core)
230nF 100mA
55.0Ω
1500 2000 2000
Maximum Capacitance
(Core-Screen)
410nF 200mA
27.5Ω
760 1130 1860
Insulation Resistance
(Core-Core and Core-
Screen)

2M Ω
300mA
18.3Ω
500 750 1200
NB: Maximum Circuit Impedance is the sum
of the resistance of both cable conductors.
400mA
13.7Ω
380 560 920
500mA
11.0Ω
300 450 740
5.2.2 Sounder Circuit Lengths
The voltage drop on each alarm circuit should be calculated to ensure that the minimum voltage at the end of
the circuit exceeds the minimum required by each sounding device at the minimum alarm circuit output voltage.
The voltage at the end of the circuit is given by:
Minimum Alarm Voltage = V
OUT(MIN)
– (I
ALARM
x R
CABLE
)
Minimum Output Voltage (V
OUT(MIN)
) is V
BAT(MIN)
– 0.5V = 20.5V
Alarm Current (I
ALARM
) is the sum of the loads presented by the sounding devices in alarm
Cable Resistance (R
CABLE
) is the sum of the cable resistance in both cores x cable length.
Cable Resistance (R
CABLE
) for 1.0mm
2
is 0.036Ω / metre
Cable Resistance (R
CABLE
) for 1.5mm
2
is 0.024Ω / metre
Cable Resistance (R
CABLE
) for 2.5mm
2
is 0.015Ω / metre
Insulation Resistance
(Core-Core and Core-
Screen)

2M Ω
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