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1: GENERAL DESCRIPTION
1:1 Switchgear:
The AST3225 transfer switch mechanism consists of a basic mechanical switching
assembly that can be configured to satisfy various application requirements. (UL listed
E200939 Switch Mechanism). This manual describes the AST3225-2 model. (General
Arrangement page 14)
1:1:1 Specifications for AST3225-2 model
Normal/Emergency/Neutral Lug Connections 300
MCM MA Load connections 320 MCM (Max Wire
Size)
VOLTAGE NORMAL
208/240
EMERGENCY
208/240
Amperage 225 225
Hz 60 60
Ph Single
Single
Poles 2 2
Transfer Motor: 120V 60 HZ 2.3 amps thermally protected
Withstand/interrupting rating: symmetrical 10 KA. for loading at 100% of nameplate
current Enclosure: 24” wide x 30” high x 9” deep. NEMA 4.
1:1:2 Operation:
The AST3225 includes the suitable sensing circuitry for automatic transfer of an
electrical load to a stand-by power supply in the event of a drop or loss of voltage of any
or all phases of the normal power supply. Upon the restoration of the normal supply, the
electrical load is automatically re-transferred to the normal power supply.
The transfer motor utilizes power from the source to which the electrical load is being
transferred. The mechanism provides a positive mechanical interlock to prevent both
switches from being closed at the same time. The AST3225 also incorporates the basic
actuating motor control switches, terminal blocks, and voltage sensing connection points
for Utility Line sensing. Provision is also made for manual transfer of the power sources
if necessary. Instructions for the manual procedure are located on the operating arm of
the mechanism. The AST3225 mechanism is a lever-operated device controlled by a 120
volt unidirectional gear-motor.
The transfer motor drives a crank that in turn operates an aluminum lever arm, by sliding
a nylon slider between the top and bottom parts of the arm assembly. The lever, in turn,
operates the two switch handles by means of a unique spring and roller arrangement. The
travel position of the aluminum lever is detected by two micro switches, which in turn
disconnect power to the transfer motor, when appropriate.
Manual for AST3225
Automatic
Transfer Switch
