Apollo AAN-4, Hardware Manual

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29 AAN-4 Hardware Manual
© 2011 Apollo Security Inc.
3.6.1 Strike Wiring, General
Typically, doors are held closed and released by one of two methods. An electric door strike is installed in the
door frame, replacing the mechanical strike plate. This type of strike has a “gate” that is normally held closed
and is released by command from the reader. This allows the door to be opened. A second type of lock is a
electro-magnetic lock which is a two piece device mounted on the perimeter of the door. A solid plate is
mounted to the door and a electro-magnetic lock is mounted adjacent to the plate on the frame of the door.
The electro-magnetic lock firmly holds the plate mounted to the door, holding it closed until the power is
removed by the reader, allowing the door to be opened.
Most electric locks are available in two configurations, Fail-Safe and Fail-Secure. Fail-Safe locks require
power to hold the door closed and will release the door when power is removed. This type of lock will open
the door if a power outage occurs. This is desirable for doors used as emergency exits. Fail-Secure locks
hold the door closed automatically and require power to release the door. This type of lock is desirable for
securing doors in high security applications. Electro-Magnetic locks are typically only available in the
Fail-Safe configuration.
Electric locks are also available in a range of operating voltages. 12 volts DC or 24 volts DC are the most
common. AC power strikes are also available but are not widely used because of the difficulty in connecting
suppression circuitry (see Part 3.6.5.2) and the inability of providing battery backup power in the event of
power failure. If a 12 or 24 volt DC lock is selected, the same power supply used to power the lock may be
used to power the reader. UNDER NO CIRCUMSTANCES SHOULD AC POWER BE APPLIED TO THE
AAN-4 READER INTERFACE!
A typical electric door lock (strike) will require approximately 250 mA. (.250 amps) to control. The relay
contacts on all Apollo relays are capable of switching up to 24 volts DC at up to 2 amps. If the particular
locking device requires more that 2 amps to control, a separate, external relay capable of switching the
required amount of current must be installed.
The AAN-4 provide two methods of strike control for each reader. The first method is by use of the internal
strike relay. Four such relays are provided on the AAN-4—one for each reader input. Each is rated for
switching 2 amps at up to 24 volts DC. Connection of this internal relay is covered in Part 3.5.3 The reader
also has the capability of connecting external, high security relay modules (ADA-10/11) for control of the
electric lock as well as other outputs. Connection of these external relays is covered in the following sections.
Use of the internal relay provides for a simple, cost effective method for connection of the door strike with a
reduced level of security. If someone physically access the strike relay wiring, they may be able to release
the door. The external relays (ADA-10/11) are designed to eliminate this possible security breach.
Wiring between the strike power supply, strike relay (internal or external) and the electric lock should be of
sufficient gauge to prevent excessive voltage drop under all circumstances.
ALL ELECTRIC LOCKS MUST HAVE A SUPPRESSION CIRCUIT INSTALLED TO PREVENT EXCESSIVE
INTERFERENCE WITH OTHER SYSTEM COMPONENTS WHEN THE POWER IS REMOVED. SEE THE
FOLLOWING SECTION FOR INFORMATION ON SUPPRESSION INSTALLATION.
3.6.2 Strike Suppression Installation
Most electric locks consist of several components, one of which is usually a coil of wire that acts as an
electro-magnet to either release the door (Fail-Secure) or hold the door closed (Fail-Safe). This coil of wire
acts as a large inductor. When DC power is applied to a large inductor, energy is stored in the inductor.
When the circuit is broken (power is removed) this stored energy is converted to a very large voltage and
attempts to travel down the wires connected to the strike. IF SOME METHOD IS NOT UTILIZED TO
REDUCE OR SUPPRESS THIS VERY LARGE VOLTAGE, IT CAN CAUSE COMMUNICATIONS
PROBLEMS, PERMANENT DAMAGE TO THE STRIKE RELAY, AND PERMANENT DAMAGE TO OTHER
SYSTEM COMPONENTS!
The most common method of suppression used on DC power strikes is installation of a reverse biased diode
as close a possible to the strike itself. Any type of general purpose diode (1N4001 – 1N4006, etc.) will work