The Allen-Bradley 1336R-PRE-SP1A pre-charge printed circuit board (PCB) is one of the 2 main components comprising the 1336 REGEN line regeneration drive accessories series, This board prevents the excessive accumulation of voltage in the DC Bus of variable frequency drives (VFDs). This type of line regeneration device is employed in dynamic applications where motors are constantly starting, stopping, braking, deaccelerating, and overhauling (such as when a motor is rotating faster than its designated speed) such as downhill conveyors, cranes, flywheels, elevators, and centrifuge applications. Motors are complex machines that convert electrical energy into mechanical energy, but they can also act as generators and produce a counter-electromotive force that is normally dissipated as heat. With the use of regenerative drives, the energy produced by a motor in the generator mode (when the motor’s synchronous speed is less than its rotor speed) can be fed back onto the 3-phase AC utility line, so that it can be re-used by other equipment, unlike what normally happens with traditional dynamic brake systems.

The 1336R-PRE-SP1A pre-charge PCB contains a 3-phase contactor with a monitoring circuit in place to send information about the phase and magnitude of the AC line to the control board in the 1336R converter. Another important function of the 1336R-PRE-SP1A PCB is to limit the inrush current to the system. With an operating voltage of 460 Volts, and a current rating of 48 to 78 Amps, the 1336R-PRE-SP1A pre-charge PCB must be treated with all the necessary precautions and only experienced and qualified technicians should be allowed to perform maintenance routines or inspections in the board.