FROM: James D. Herberg, General Manager
Originator: Riaz Moinuddin, Director of Operations & Maintenance
SUBJECT:
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MAIN SEWAGE PUMP VARIABLE FREQUENCY DRIVE TRANSFER SWITCH AND UNINTERRUPTABLE POWER SUPPLY SYSTEM IMPLEMENTATION AT PLANT NO. 2
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GENERAL MANAGER'S RECOMMENDATION
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RECOMMENDATION:
A. Approve a Sole Source Purchase Order Contract to One Source/Rockwell Automation for modifications to the six main sewage pump Variable Frequency Drives for a total amount not to exceed $103,628; and,
B. Approve a contingency of $10,363 (10%).
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BACKGROUND
The Orange County Sanitation District (OC San) Plant No. 2 headworks facility is designed with seven main sewage pumps. Variable Frequency Drives (VFD) are used to control the speed of the main sewage pumps to maximize efficiency of the pumping operation. These VFDs have integrated Uninterruptable Power Supply units. These integrated Uninterruptable Power Supply units are obsolete and no longer available.
One of the seven integrated Uninterruptable Power Supplies failed in 2020. It was determined that off the shelf replacements have compatibility issues with the existing internal VFD communication network that results in a failure of these critical pumps to start when switching from primary to back-up power. In 2020, a solution was developed by the original equipment manufacturer and was implemented successfully on the failed main sewage pump VFD.
RELEVANT STANDARDS
* Maintain a proactive asset management program
* Maintain a culture of improving efficiency to reduce the cost to provide the current service level or standard
PROBLEM
The Main Sewage Pumps at Plant No. 2 pump sewage into the treatment plant. Six of the seven VFDs that power these critical pumps contain obsolete Uninterruptable Power Supplies that are no longer available. Failure of these units limits the availability of this critical pumping system.
PROPOSED SOLUTION
Approve a Sole...
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