Refurbishing Aged MCCs Proves Beneficial
Joseph C. Pearson and Dilip A. Pandya, United States Postal Service
Innovative ideas improve 276 buckets, save $1.8 million
In 1999-2001, the New Jersey International & Bulk Mail Center (NJI&BMC) in Jersey City, one of the largest United States Postal Service facilities, was concerned about its eight 33-year-old motor control centers (MCCs). Events forced a decision to pursue options for replacing or refurbishing the 276 cells that provide power primarily to 58 heating, air conditioning, and ventilation air handling units (HVAC AHUs) for the 1.8-million-sq-ft facility.
The in-house maintenance project was completed in November 2004 without any plant shutdowns, injuries, or delays in mail processing operations or exceeding the allotted budget. The project improved safety and security for employees and facility equipment, extended overall life of the MCCs, enhanced skills of the craft crew and employees, and saved an estimated $1.8 million.
NJI&BMC usually processes more than 1 million pieces of mail daily, on a 24 hour/7 day basis. The mail volume has increased significantly for the past 20 months because of the heavy mail volume from Iraq, and other military activities.
The largest of 21 bulk mail centers, the facility’s main buildings have about 1100 conveyors, and parcel sorting and sack sorting machines, that would stretch up to 25 miles if placed end-to-end. After being sorted, mail is distributed to various postal facilities and international shipping docks on a daily basis from 305 truck bays.
In 1999-2001, the facility experienced three incidents where aged components in various MCC cells malfunctioned, resulting in minor explosions and fire. Maintenance personnel were successful in containing the fires and preventing any additional property damage or any personnel injuries. Based on these experiences, it was decided to explore cost-effective options for replacing or refurbishing the 276 buckets.
33-year-old MCC before refurbishment
MCC at completion of project
Internal components of original MCC
Internal components of refurbished MCC
Option one: replacement
Option one was the traditional and easiest option—procuring and installing new MCCs. This would require intensive on-site field work including disconnecting approximately 3000-4000 wires, removing eight MCC cabinets from the fourth floor penthouse location, reconnecting all load and line sides of the MCC cells, and then testing, validating, and accepting all field wiring. This would also result in costly electricians’ field hours and overtime.
An electrical engineering consultant conservatively estimated the cost of replacing all eight MCCs/276 cells at approximately $1.5 million: $560,544 for material, $680,000 for labor (disconnecting, removing, disposing, reconnecting, and testing 276 cells), and $250,000 for architect/engineering services, project management, design, engineering, contingency, and construction. Other incidental costs, such as downtime, utilization of facility resources, restoring the facility to normal conditions, and shutdown costs, were not included in this estimate.
This option would require several planned shutdowns. Since the facility operates on a 24/7 basis, any inadvertent switching actions or faulty wiring would impact the routine and severely hamper mail processing operations. Scheduling and coordinating active MCC outages in a safe and secure manner also would require additional maintenance resources and manpower. Facility shutdown costs, based on past experience, are approximately $75,000/hr, and directly impact revenue.
Option two: revitalization
The possible plant shutdowns, high costs, and the potential for jeopardizing safety and security of employees and equipment forced investigation of an alternate option. Discussions with the maintenance technical and craft personnel who ultimately would be responsible for any work led to the decision to examine revitalization and refurbishment of the internal consumable components of the MCCs. This option immediately relieved the staff from scheduling and coordinating outages of complete MCCs, and there would be no plans for any restoring and normalizing of plant operations.
The estimated cost for this option was $435,000. The Purchasing and Supply Chain Management office in Windsor, CT, reviewed, analyzed, and processed this concept for final installation and estimated that the project saved $1.8 million for USPS.
One of the main reasons for this significantly lower cost was that this option re-used nonmoving existing components (bus work, metal frames, power and control cables, conduits, cable trays, approximately 3000-4000 external wires, etc.) without disrupting or jeopardizing any field wiring. This concept replaced all consumable items and moving parts such as contactors, relays, fuses, circuit breaker, selector switches, indicating lights, and internal wiring.
Furthermore, the plan indirectly enhanced in-house skills by using the facility’s own employees. From the beginning, the craft personnel were interested in replacing the aging cells. They actively participated in configuring component layout, testing experimental cells, and modifying wiring and component layout that enhanced safety and ease of maintenance. They also participated in ranking and selecting the supplier for the refurbished buckets.
Field-testing prototype cells
Since this retrofitting concept had not been undertaken on such a large scale in any postal facility or any other industrial site, the maintenance staff asked three suppliers who had experience in completely re-building MCC cells to make prototype test cells and install them at the site for actual field testing. Maintenance employees prepared and completed design, wiring diagrams, and sketches to suit the existing field wiring and layout. They removed three existing cells, gave them to the suppliers, and asked them to retrofit for variable frequency drive (VFD) applications. The cells were chosen because they were more complex, congested, and difficult to work on.
The retrofitted cells were field tested for approximately 4 months. The original VFD cell design was problematic, so the cable routing from VFD to contactor, starter, and motor was reconfigured. All suppliers provided new contactors, LED indicating lights, control transformer, breaker, control switch, timer, wiring, stabs, etc. However, the component layout and wiring configuration varied per supplier’s preference and design.
Selecting a supplier
After completing the initial field testing and validating the concept, the Purchasing and Supply Chain Management office prepared and issued a complete bid solicitation package, including scope of work and terms and conditions. In conjunction with procurement personnel, the maintenance team evaluated bids. Craft personnel provided primary input, specifically looking for ease of maintenance and maintaining plant safety requirements. They provided significant recommendations on maintenance issues regarding performing PM or replacing the cell.
From a previous project—replacing 150 600V FPE circuit breakers—the team learned the value of selecting a supplier within the metropolitan area of the facility. Its 24/7operation demands immediate services in instances where the supplier is needed on-site for emergencies.
Five team members—a procurement specialist, the electrical engineer, the preventive maintenance engineer, the manager of maintenance operations, and an electronic technician—actively participated in ranking and selecting Gavan-Graham Electrical Products Corp., a local panel board assembler who agreed to meet requirements and satisfy terms and conditions as specified in the bid solicitation package. The company was helpful in satisfying and accommodating changing schedules and site-specific requests.
In the last week of November 2002, the maintenance team removed approximately 50 existing cells and the supplier picked them up for retrofitting. At the factory, technicians removed all internal components, discarded all wiring, and cleaned, anodized, and painted the cell structures.
Based on the approved wiring schematic, the technicians rebuilt the cells, using new control transformers, new LED indicating lights instead of regular bulbs, control selector switch, contactors, timers, solid state relays, fuses, plug in terminal blocks for both power and control wiring, etc. This batch of cells was to be retrofitted for VFD applications.
Designing a test-bench cell
The maintenance staff wanted to standardize a unique testing procedure for each of the 276 cells. Using technicians to test individual wiring induced human errors and higher costs. The supplier resolved the problem by designing and assembling a separate test-bench cell in the factory to bench test all wiring and to simulate various operating conditions displaying proper LED lights. The supplier also agreed to test every cell prior to final shipment to NJ&BMC. This innovative idea was beneficial for the maintenance crew because it reduced significant manpower and field wiring headaches at NJ&BMC.
All 276 cells were bench tested at the factory to ensure workability.
On February 11, 2003, the team completed acceptance testing of the test-bench cell at the factory. The electronic technician selected two random cells from the 30 cells that were ready for final shipment. One cell failed the testing protocol and required wiring changes. This test demonstrated various operating parameters that were validated by the red, green, and white LED lights. Bench testing each of the 276 cells prior to final shipment prevented any inadvertent wiring errors and damage at NJ&BMC.
Replacing MCC cells
Removing existing cells from the working MCCs and installing retrofitted cells in a safe and secure manner needed close coordination among various departments because of the major hurdles to overcome. The team realized that retrofitting 276 cells would be difficult and would take more time than earlier estimated, especially since it was accomplishing this work while the facility was operating at its optimum capacity, and without imposing any major impact on mail processing operations.
During the second week of February 2003, the team successfully completed installing the first set of 30 VFD cells without any problems, and continued replacing additional cells as feasible. Initially, it had minor problems retrofitting two cells because the back stabs did not align with MCC buses. The supplier noted and corrected deficiencies immediately.
As indicated previously, certain portions of this job were more complicated. When staff opened the size 5 starter’s buckets for inspecting internal components and for disassembling one of the largest cells, it could not pull out the buckets because the main breakers were directly connected to the main MCC buses. These buckets, as compared to other buckets, did not use easy pull-out stabs. Instead, the circuit breaker was directly connected to main buses via heavy cables. Power was shut down for removal and installations of these buckets.
Furthermore, reconfiguring and rerouting load and line side power cables and auxiliary control cables were challenging for the on-site crew. It also found that all of the size 5 buckets were not identical as previously thought. The supplier had to rewire each bucket to suit the individual bucket wiring design, and craft personnel had to reconfigure load and line side cables.
The retrofit concept was challenging and difficult for maintenance because the maintenance function, in general, is mandated to conduct periodic PM and to maintain the buildings, equipment, and grounds. Usually an architect/engineer would design, engineer, manage construction, and complete installation. Instead, maintenance staffers managed maintenance resources successfully and completed design, engineering, removal, and installation themselves. Project-related work such as this is considered lower priority and usually takes longer to complete.
Combining small starters
Approximately 100 size 1 starters were designated for exhaust fans and door heaters. The exhaust fan motors, in general, were drawing 0.9-4.2 A, whereas the door heater fan motors varied from 4-10 A. It was decided to combine and standardize two lower-A-drawing cells into one cell. This combined cell would be retrofitted with one circuit breaker, two control switches, two sets of LED indicating lights, separate wiring, two contactors, and one control transformer. The electrical architect/engineer (Triad Consulting Inc.) verified that the short circuit rating and other safety parameters were within the acceptable ranges, and the combining concept would increase the number of spare starters by 50 percent.
External and internal views of combined small starters cells
In the last week of March 2003, the supplier retrofitted one of the prototype combination cells and it was installed in the MCC-F-1, 6A for bay door heater fan motor 37 and 38. This concept was proven successful, and resulted in increasing existing power distribution capability in the MCCs by approximately 50 percent. The facility gained these advantages without any major modifications to the MCC cabinets, and at minimal cost to the USPS.
From March to August 15, 2003, there were no problems with this experimental cell and the team continued combining cells where feasible. As of April 2005, there have been no operational problems with these combined starters cells.
Based on its limited experience, the maintenance team recommends the following key items when replacing/retrofitting MCCs:
• Encourage maintenance craft personnel input from the beginning of any retrofitting on-site projects.
• Complete thorough investigations of existing equipment, inspect and validate consumable and nonconsumable parts.
• Realize that retrofitting and replacing internal MCC components can save capital cost and maintenance resources and extend life expectancy of the equipment.
• Perform extensive field testing of prototype cells on-site prior to authorizing additional work.
• Assess need for an on-site standby power source, if shutdown is inevitable.
• Emphasize on-site immediate response from the supplier when necessary.
• Prepare detailed planning and step-by-step procedures to minimize operational impact.
• Review safety and environmental issues with on-site experts prior to initializing the project
Checking, validating field testing, and revitalizing the 33-year-old MCCs did improve life expectancy, enhance safety and security, reduce maintenance resource requirements, improve maintenance skill sets, and lower overall costs.
The authors appreciate the support from the following organizations and USPS personnel:USPS NJ&BMC: Frank P. Tulino, plant manager; Edward P. Pfeiffer, preventive maintenance engineer; Tom Finan, electronic technician; senior maintenance operations supervisors; and managers of maintenance operations. Windsor, CT, P&SCM: William F. Blazinski and Manager Robert A. Bress. USPS NewYork area maintenance support: Leon Roszkowski, Nick Borg, and Manager Guy Miata. Gavan-Graham: Emerson Crooks. Triad Consulting: Paul Witwick and Ron Regan.
Joseph C. Pearson has been the manager of maintenance at the United States Postal Service’s New Jersey International & Bulk Mail Center for the past 15 years. The facility’s maintenance department consists of approximately 500 managers, engineers, and craft employees. Dilip A. Pandya has been the electrical engineer at NJ&BMC for the past 5 years and manages electrical requirements for the facility. He is responsible for investigating and implementing innovative cost-effective technologies. He can be contacted at (201) 714-6727.