Starter Units

As stated earlier, up to six motor starter units can be mounted in each vertical section. The components of each motor starter unit are mounted in a two-sided steel frame called a draw-out unit or bucket. All components needed to control a motor are mounted in this starter unit frame:

• The primary disconnect and the operator handle are mounted at the left side of the starter.

• A motor starter (magnetic contactor and overload relay) is mounted at the center of the back panel.

• Push buttons, indicator lights, and selector switches (as required) are mounted on a device bracket located on the unit cover door.

• Terminal blocks for power and control wiring are mounted vertically at the right side of the unit, adjacent to the vertical wireway, permitting interconnections between units, motors and remote control circuits.

On the rear panel of each starter unit, three sets of contact fingers (stabs) are mounted in an insulated bracket, forming a stab assembly. When the starter unit is installed, the stabs fit into the vertical bus assembly and make contact with the vertical power bus. This provides operating power to the unit components. Within the starter unit, the stabs are wired to the line side of that primary disconnect device. Power from the vertical bus is routed through the stab assembly and disconnect device to the other components in the unit.