8520-3SA12

The Allen-Bradley 8520-3SA12 is the servo amplifier power unit for the Allen-Bradley 9/440 3-axis CNC system. The defining feature of this kind of system is the integration of a CNC device and a digital drive into one system. This integrated system offers many benefits including an enhanced performance as well as reduced expense, a reduced time necessary for system integration, and reduced cabling requirements. The 9/440 3-axis CNC system can support as many as 3 axis modules, up to 3 resolver feedback ports and 2 analog outputs but only 1 encoder feedback port. The 9/440 system is comprised of the following two modules: a system module such as the 8520-3SA12 and an axis module.

The CNC assembly, the power assembly, and the interconnected power and CNC assembly make up the whole Allen-Bradley system module. The CNC assembly is composed of a processor board with connections to the Allen-Bradley 9/Series fiber optic I/O rings, serial ports marked as Port A and Port B, an emergency stop feature, the ability to support video connections, and with a feedback board which provides connection to the resolvers on 1326 series motors. The power assembly is the part of the system that supplies electrical power to the 8520-3SA12 system module and to all of the axis modules. The interconnected power and CNC assembly have a wiring board that can interface with the 9/440 CNC assembly and with the power portions of the 9/440 system. DC power is available at the 8520-3SA12 system module’s output. The CNC assembly’s axis modules are mainly responsible for converting this DC power to AC power (the AC power has controlled phase, amplitude, and frequency). This voltage is used for controlling the speed, the torque, and the direction of the 1326 AC servomotors which are connected to the 8520-3SA12 and the 9/440 system.