PS20-BRD v3.2 EN Rev.A.doc
2008-04-08
Power Supply Module 13.8V/2A
Type PS20-BRD
v3.2
P
RODUCT
D
ESCRIPTION
The PS20-BRD module is a spare part for PS20 power supply however it can be also used
as autonomic power supply module. If used autonomously PS20-BRD requires 18-22VAC
and 40W of power and may deliver up to 2A DC current without any time limit. PS20-
BRD utilizes DC/DC switched mode electronic circuit which offers high efficiency and
small size. Also, it employs internal current limiting and short circuit protection which
make it essentially indestructible. The reserve battery is connected to output terminals
trough an ultra low-resistance MOS transistor, such a circuit architecture enables
optimum performance during AC failure and during dynamic changes of load when
excessive current consumption is required. PS20-BRD charges battery with constant
current-constant voltage method, this method of charging guaranties relatively quick and
safe charging process. The initial charging current is factory set to ~300mA, installer
should be aware that with battery connected to PS20-BRD the total output current will be
reduced to 1.7A. Depending on battery charging phase the output voltage of PS20-BRD
may vary from approx. 11.5 up to 13.8V level. When battery voltage drops below ~10.0V
level internal circuit disconnect it from load, battery is automatically reconnected when
AC supply returns. Battery cut off circuit protect battery from deep discharge whereas
the equipment connected to power supply from operation below 10.0V level which in
many cases can lead to undefined system behavior. Battery is protected with 5A fuse
which reduce maximum output current sourced from battery and protects electronic
circuit against battery reverse connection. PS20-BRD offers two output ports (Z1 and Z2
terminals). The nominal output voltage is factory set to 13.8V and should not be changed
by user. PS20-BRD is equipped with two LEDs, the first one (red) indicates that module
has AC supply while the second one (green) indicates DC output voltage.
PSAM-1
A
LARM
M
ODULE
If required PS20-BRD can be equipped with optional PSAM-1 alarm module. The main
purpose of PSAM-1 module is to detect and indicate an alarm situation of power supply to
the external device or system. The PSAM-1 may operate in autonomic or networked
mode and can indicate following conditions:
-
low battery
-
battery failure
-
AC supply lost
-
DC output overload (this state is indicated in networked mode only)
-
DC output level (this state is indicated in networked mode only)
In autonomic mode alarm states are indicated on three transistor outputs: ACL, LB and
BF and on internal buzzer. These outputs can be connected to external control panel,
access controller or another control device which will warn authorized personnel.
Normally, all outputs are in high resistance state, when triggered they switch to supply
minus. The maximum current which can be sink by these output is internally limited to
20mA while the maximum applied voltage should not exceed 15V.
The ACL (Alternative Current Lost) output switches to active state when there is a lack of
AC supply and it lasts for more then 4 minutes. Output returns to normal state
immediately after AC supply returns. The LB (Low Battery) output is triggered when
battery level drops below ~12.0V, it return whenever battery level rise above 12V. The
BF (Battery Failure) output is triggered in case of any situation listed below:
-
Battery fuse is off
