Activity based costing

Dear Guys,

In maintenance workcenter in the costing tab,I have maintained Cost center 500(admin cost center)with activity INST(I have definedRs 500 /hr in KP26).

Iam using this workcenter in Maintenance order for equipment XXX(cost center-200 in account assignment) and upon releasing the order , settlement rule will get created for cost center 200.

The total operation hours confirmed is 20 hours and on settlement ,Rs 10000(500x20) is settled on cost center 200(responsible costcenter for equipment).

Then what is the point of giving Admin cost center in Maintenance Workcenter?

Is it required only for assigning activity type in KP26?

I request you to clarify this please .

Regards

ISWARI