Mechanical Electrical Systems Inc. designed, assembled, and wired a web line system that will add 4 inverters to a existing plastic film web line.  These inverters will be controlling motors that will Unwind, Preheat, Pickoff Nip, and Cool the web line.  The system for the web line will be controlled with the Parker 890 series inverters.  The Parker 890’s  have been put together with a common DC bus configuration as seen below.

Parker 890 Series Inverter

The Parker 890 series inverter is commonly referred to as a bookshelf inverter.  This is because when assembled together, they have no spacing between inverters and looks like books on a shelf. The Parker 890 is a din rail mounted inverter, to ease installation and disassembly.  The first inverter on the left side is a common supply(CS) inverter, which takes in the AC voltage in the bottom of the inverter and converts it to DC.  The CS inverter then supplies DC power to the other inverters on the common DC bus.  This is done with the bus bar across the top of the inverters.  This web line system upgrade also has 2 spare inverters seen on the second row.

Web Line System Features

Mechanical Electrical Systems Inc. remote mounted the keypads on the door of the system.  This addresses the safety concerns of getting into the control cabinet of a system that is powered on. MES also mounted a braking resistor on the bottom of the control panel, which is connected to the common supply inverter.  With the braking resistor, the system can decelerate the motors without worry of the DC bus voltage getting to high.  If the braking resistor isn’t installed the inverter will try to decelerate the motor until the DC bus voltage goes above the threshold.  When the DC Bus voltage goes above the DC threshold the inverter will trip or fail.  Basically without the braking resistor installed the system will not perform as it was designed to do.