2903 Power Supply
Installation Instructions
I-EA00003
FEATURES
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Filtered/Regulated 24 Volts DC
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Up to Full 2 Amps Load Capacity
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Class 2 Rated Outputs
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Overload, Over Voltage, and Short Circuit Protection
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Automatically Accepts 120VAC or 240VAC Input Without Requiring to Move Jumpers or Set
Dip Switches
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Controls Fail Safe or Fail Secure Locking Devices
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Interface Relay Isolates Locking device current from control switch
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Auxiliary 24VDC Constant Voltage Output for Powering Stand Alone Devices, Such as
Keypads, Motion Detectors, and Status Indicators
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Surge Suppression on Fail Safe & Fail Secure Outputs
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UL Listed and Tested to 294 Standard for Access Control System Units and to Canadian
Standard CSA C22.2 No. 205 for Signal Equipment
REV 2
Page 1 of 4
INSTALLATION INSTRUCTIONS
The unit must be mounted indoors and away from any moist or wet areas.
(For Canada, this unit shall be installed in accordance with the "Canadian
Electrical Code, Part I".) Some common locations for mounting 2903 would
be in the plenum near the door containing the electric locking device or in a
nearby closet or electrical room.
When installing the unit in the plenum, wires must either be of plenum rating
or contained inside conduit. The unit must be mounted in a vertical position
with the power supply module located at the top, as shown in the photograph
above. Four 1/4” holes are provided for mounting the box to the wall or other
rigid surface. If the surface material is wood, it must be at least 1 inch thick.
Use either a truss or pan head, 1 inch long sheet metal screw (#10 or larger)
for fastening the box to the wood surface. When mounting the unit to 1/2
inch or 5/8 inch dry wall, it is recommended that 3/16 inch or 1/4 inch
diameter toggle bolts be used for maximum support. Use the same size
toggle bolts for mounting the unit to hollow concrete blocks. For mounting to
concrete, solid block, or brick, it is recommended to use 1-3/4 inch long
(minimum) x 1/4 inch diameter hex head bolt anchors (sometimes called
power-bolts) in 18-8 stainless steel or Grade 5 zinc-plated steel. The sub
plate can be removed from the box for easier access to the mounting holes.
To remove the sub plate, locate the four #6 locknuts near each corner of the
plate and remove. The 6-32 studs, from which the sub plate mounts to, are
held in place to the box by threaded standoffs.
Wiring the AC Input
The 2903 power supply is rated for use with a 20 amp branch circuit and is
capable of accepting either 120VAC or 240VAC input without the need for
making any changes, or reconfiguring to convert from one input voltage to
the other. Because the power supply module contains Class 2 double
insulation, an earth ground wire is not required. For wiring 120VAC or
240VAC input, run 14 AWG 2-conductor to the power supply module’s input
terminals marked L (Line) and N (Neutral). Ensure that the conductors are
fully inserted into the input terminals with no bare metal exposed. (Refer to
the wire stripping instructions included on the wiring diagram attached to the
cover plate of this power supply.)
Caution: It is important to maintain separation between the primary (high
voltage AC) wiring and secondary (low voltage DC) wiring as they
are routed inside the power supply enclosure. The primary wiring
must be run inside conduit; and the conduit must be connected to
one of the knockouts located towards the left end of the top wall of
the enclosure (above and to the left of the power supply module’s
input terminals). All secondary wiring must be routed through any
one of the knockouts located along the bottom wall of the
enclosure.
Note:
This unit is not equipped with a battery standby power feature.
Control Switch
Used for indirectly switching power to fail safe and fail secure locking
devices, a control switch can be momentary or maintained action, depending
on the application. A control switch can be in the form of relay contacts, such
as used in card reader systems, motion detectors, or stand alone keypads.
Key switches, push-button switches, and emergency release type switches
(including fire alarm contacts) can also be used as a control switch for local
or remote switching of electric locking devices. It is important to ensure that
the switching device be in the form of “dry” contacts only (no voltage riding on
the switch contacts, usually referred to as “wet” contacts).
The control switch actually energizes and de-energizes an on board interface
relay. The purpose for the relay is to isolate locking device current from the
control switch contacts. Using this method of control, switches with low
current ratings can be used without the risk of becoming damaged from the
higher current of the locking device, which can be 0.5 amp or greater. The
control switch will only see low relay current (15mA) passing through its
contacts. The higher current drawn from the locking device will be switched
through the heavy duty 7 amp rated contacts of the interface relay.
Note:
To keep line drop (voltage lost due to resistance in the field wire)
to a minimum, it is recommended that an 18 gauge stranded two
conductor cable be run from the 2903 to each electrified locking
device (or two locking devices if required on pair door
applications). Each separate run must not exceed 500 feet. The
control switch, however, can be located several hundred feet
further from the power supply with hardly any voltage lost on
account of the high impedance of the relay coil (1,600 ohms).
