P-2. Design for lowest system cost

Choose cheapest drive system for variable speed operation of the centrifugal pump in water supply system.

Given parameters:

• Rated flow 50 l/s, head 200 m, pump efficiency 81%
• Speed range 0 - 1450 rpm
• Grid voltage – 400 V
• The pump works in its rated point
• Clean electric room for FC with abundant heat removal capabilities
• Distance from the electric room to the pump - 30 m
• Conditions at the place of the pump installation - wet
• Pump's mechanical configuration – horizontal

Sub-task: How would you design the system if we knew that normal working range of the pump is 30-80%?

Sub-task for this and other exercizes: Try to find real motors and FC in catalogues of provider from your region. e.g. Weg (for Brazil), ABB/Siemens/Danfoss (Europe).