Example 2
AlphaVision NG control panel (130mA) with 8 detectors (8 x 15mA), 1 LED keypad (8mA), 1 LCD keypad
(9mA), 1 Input + 8 OC module (58mA) with 4 magnetic contacts and 4 detectors (4 x 15mA) and 1 wireless
input module (43mA): total current drain in idle state is 428mA. We presume an extra current drain of
300mA in an alarm situation.
C20 = 18 x 0.428 + 0.5 x (0.300 + 0.428) = 0.7704 + 0.364 = 8.086Ah
⇒
battery 7,0Ah
A magnetic contact does not drain any power and the wireless components used with the wireless input
module have their own power supply.
Example 3
I/O modules have their own power supply and backup battery, so these will not influence the current drain of
the control panel. You can apply the same formula with the input + 8 OC modules and keypad placed behind
the I/O module (see example).
I/O module (74mA) with 8 detectors (8 x 15mA), 1 LED keypad (8mA), 1 LCD keypad (9mA), 1 Input + 8
OC module (58mA) with 4 magnetic contacts and 4 detectors (4 x 15mÀ) and 1 wireless interface (43mA):
Total current drain in idle state is 372 mA. We presume an extra current drain of 300mA in an alarm
situation.
C20 = 18 x 0.372 + 0.5 x (0.300 + 0.372) = 6.696 + 0.336 = 7.032Ah
⇒
battery 7,0Ah
Maximum distance between modules and power supplies
Standard RS-485 cable
We advise the use of the standard RS-485 cable (product number 008654). This is a twisted pair, 4 wired,
shielded cable with a fixed ground wire and an ohmic resistance of 10 ohms over every 100 meters. In the
following calculations we assume the use of this type of RS-485 cable.
Keypads
An LCD keypad uses up to 9mA (with all LED’s on). Using the recommended RS-485 cable this will mean
a voltage drop of 0,09V for each 100 meters. An LCD keypad needs at least a power voltage of 8V, in the
worst situation (no mains power and minimal battery voltage). The maximal distance between an LCD
keypad and the nearest power supply will, with a voltage drop of 2V, in theory be 2200 meters. So, an LCD
keypad can be placed 1200 meters from a power supply (1200 meters is the maximal length of the RS-485
bus).
An LCD/Prox keypad uses up to 50mA (with all LED’s on). Using the recommended RS-485 cable this will
mean a voltage drop of 0,5V for each 100 meters. An LCD/Prox keypad needs at least a power voltage of
8V, in the worst situation (no mains power and minimal battery voltage). The maximal distance between an
LCD/Prox and the nearest power supply will, with a voltage drop of 2V, be 400 meters.
A LED keypad uses up to 8 mA (with all LED’s on). Using the recommended RS-485 cable this will mean a
voltage drop of 0,08V for each 100 meters. A LED keypad needs at least a power voltage of 8V, in the worst
situation (no mains power and minimal battery voltage). The maximal distance between a LED keypad and
the nearest power supply, with a voltage drop of 2V, will in theory be 2500 meters. This means that the LED
keypad can be placed up to 1200 meters from the nearest power supply, since 1200 meters is the maximal
bus length.
Attention:
Make sure to read the information at “dipswitch settings and keypad address instructions”.
AlphaVision NG installation manual Rev. 2.0 27-08-2003 Blz. 30/101
