Title
Resolution to Approve the Purchase of Two Allen Bradley, Power Flex 700, Variable Frequency Drives from McNaughton-McKay Electric Co. for Effluent Pump Motors at the Wastewater Treatment Plant ($46,080.00)
Memorandum
Your approval is requested to authorize a purchase order with McNaughton-McKay Electric Company for the acquisition of two variable frequency drives (VFDs) to replace two failing obsolete VFDs on effluent pump motors at the Wastewater Treatment Plant (WWTP) in the amount of $46,080.00.
These machines were installed nearly 30 years ago and have exceeded their useful life. Two of four old VFDs were replaced last year. Replacing the last two VFDs will complete the renovation of all the effluent pump motor VFDs.
VFDs are used to improve energy efficiency and maximize operational control of alternating current motors. The WWTP uses Allen Bradley, 1336 Classic, VFDs to control four of six 150 H.P. effluent pump motors in the plant's water reclamation tertiary treatment process. Failure of a VFD at this stage in the process would be detrimental to the control of effluent flow to the sand filters by increasing the frequency of filter backwashing to keep the filter free of solids. Without VFD control, flow through the ultra-violet disinfection system would not vary proportionally to required disinfection demand causing higher operational costs. Plant energy utilization would also be adversely impacted by such a failure because these large motors draw correspondingly large currents at each startup.
Over the past five years the VFDs have failed several times for reasons associated with the electronic circuit boards and power transistors. The Allen Bradley, 1336 Classic, VFD is listed by the manufacturer as a discontinued and obsolete product. Since the manufacture of the Allen Bradley, 1336 Classic, VFDs have been discontinued, the production of circuit boards for the drive has ceased. No new circuit boards are available for immediate replacement. A faulty circuit board has to be returned to the manufacturer for repair at a cost that represents a large fraction of the cost of a new VFD.
WWTP staff has worked with engineers from McNaughton-McKay Electric Co. and Rockwell Automation, the parent company of Allen Bradley, to determine if retrofitting a new VFD into the existing drive enclosure with its associated manual and by-pass control circuits was feasible. After investigation, it was determined that an Allen Bradley, Power Flex 700 VFD could replace, with minor alteration, the 1336 Classic VFD maintaining the plant's existing cabinet, by-pass circuits and manual controls. Rockwell Automation engineers would provide installation drawings, electric schematics and startup support if the drives are purchased.
The Wastewater Treatment Plant has standardized on Allen Bradley VFDs because they are reliable, meet the operational standards required for use with the plant's computerized process control system, allow the plant to purchase and store spare parts cost effectively and train staff more efficiently for the operation and maintenance of this equipment.
After reviewing performance specifications, WWTP staff recommends the purchase of two, Power Flex 700, VFDs from McNaughton-McKay Electric Co at a unit price of $23,040.00 and a total cost of $46,080.00.
McNaughton-McKay Electric Co. is the sole distributor of Allen Bradley, variable frequency drives in Michigan; competitive bids were not solicited.
McNaughton-McKay Electric Co. received Human Rights approval on January 8, 2010 and complies with the city's living wage requirements.
Funds to finance this purchase are included in the approved FY10 WWTP Operation and Maintenance Budget for the Sewage Disposal System.
Staff
Prepared by: Ed Sajewski, WWTP Contract and Project Services Manager
Reviewed by: Sue F. McCormick, Public Services Administrator
Approved by: Roger W. Fraser, City Administrator
Body
Whereas, Variable Frequency Drives (VFD) are used to improve energy efficiency and maximize operational control of alternating current motors;
Whereas, the Wastewater Treatment Plant uses Allen Bradley, 1336 Classic, VFDs to control motors in the tertiary treatment facility and they have exceeded their useful life;
Whereas, retrofitting new Allen Bradley, Power Flex 700, VFDs into the existing enclosures is feasible and recommended by city staff;
Whereas, McNaughton-McKay Electric Co. is the only distributor of Allen Bradley, Power Flex 700, VFDs in Michigan;
Whereas, McNaughton-McKay Electric Co. received Human Rights approval on January 8, 2010 and complies with the city's living wage requirements; and
Whereas, Funds to finance the purchase are included in the approved FY10 WWTP Operation and Maintenance Budget for the Sewage Disposal System;
RESOLVED, That City Council approve the purchase of two Allen Bradley, Power Flex 700, VFDs from McNaughton-McKay Electric Co. in the amount of $46,080.00, and
RESOLVED, That the purchase be funded from the approved FY10 Operation and Maintenance Budget for the Sewage Disposal System.