Everyone talks about the high cost of hospital care, but for medical centers across the country, the cost to operate the building on a daily basis also continues to climb. As the largest regional medical center in San Joaquin County, St. Joseph’s Medical Center in Stockton, Calif., knows this well. The 359-bed facility employs over 400 physicians and more than 2,400 employees providing medical, surgical and diagnostic services. Operating the HVAC mechanical equipment for a facility this large is a huge energy-conservation challenge. That’s why in the 1980s, St. Joseph’s made the decision to use variable-frequency drives on HVAC pump and fan motors — a decision that continues to pay off today, thanks to an innovative upgrade plan using Danfoss VLT® variable frequency drives (VFDs).
“Starting in the 1980s, St. Joseph’s began applying VFDs on pumps and air handlers to save energy,” says Bruce Kreiss, chief engineer for plant maintenance and operations. “Over the years, that investment has paid off by minimizing electricity costs — which is especially important given recent electric rate increases in California. But after 20 years of operation, we were looking for an affordable upgrade path.”
Thinking outside the box to control costs
Rather than opt for short-sighted short-term first-cost savings of single- or two-speed motors, St Joseph’s Medical Center elected to go with the long-term energy savings obtained with VFDs. VFDs offer substantial energy savings when applied to centrifugal fan and pump motors. In fact, due to the physics of Affinity Laws, reducing fan or pump speed by 20 percent provides a potential energy savings of 50 percent.
Hospitals operate 24 hours a day, seven days a week, so most HVAC fans and pumps run well below 100 percent load, making variable-speed-drive technology an ideal solution to generate energy savings.
In the 1980s and early 1990s, St. Joseph purchased VFDs from Graham Company in Milwaukee. Danfoss acquired Graham in 1995. In 1998 and 1999, the hospital purchased 30 Danfoss VLT 6000 drives. After enjoying nearly two decades of VFD energy savings, it was clear that St. Joseph’s needed a strategy to replace these older drives.
“Danfoss drives are designed and manufactured to provide the longest service life available in the industry. Like all electronic devices, electrical component life span is determined by duty cycle, load characteristics, ambient temperatures and other environmental factors,” says Tim Smith, Danfoss DrivePro service sales manager. “In this case, the Danfoss VLT® drives were in operation over 10 years. That’s good value. But now we had to put on our thinking hats to create an affordable way to stage the replacement of the installed base.”
Due to budget constraints and the quantity and age of the drives, St. Joseph’s was looking for a flexible, long-term solution for managing its VFD assets. In 2003, Danfoss proposed a program to replace 15 old Graham drives with new Danfoss drives over a multi-year period as part of its SmartStep program.
SmartStep provides a proactive upgrade path
“The beauty of the SmartStep program is that St. Joseph’s can lock in the price of the drive and service at current costs while replacing equipment over a multi-year period,” says Smith. “In this case, the drives were legacy products from Graham, so we have a unique specific understanding of each drive. However, the program can provide service support and an equipment migration strategy regardless of the original drive’s manufacturer.”
Smith explains that SmartStep is a customizable program that can meet a wide range of customer’s long-term needs. The plan allows drive replacements to be scheduled to fit into the maintenance budget and minimizes unpredictable service expenditures. Replacing drives over a multi-year period also eliminates the huge upfront capital expense of replacing all the drives at once.
Based on the success of the 2003 SmartStep program, in 2011 St. Joseph’s purchased a program covering 47 drives — practically its entire installed base of VFDs — with 50 percent used for fans and the other 50 percent used for pumps. Sizes ranged from 100 hp for cooling tower fan motors to 1.5 hp for small pump motors. The first four drives installed under the plan were VLT® HVAC Drive FC102 models.
The FC102 drive series was developed by Danfoss dedicated for HVAC with features specifically for controlling pumps and fans — from auto-tuning, energy optimization, and monitoring. For hospital applications involving sensitive high-tech equipment, the FC102 drive incorporates protection to minimize harmonic and electromagnetic interference (EMI)/radio frequency interference (RFI) noise. These features make it easier to comply with local harmonic limitations and reduce the risk of needing to retrofit harmonic mitigation measures in the future.
The SmartStep plan includes removal of the existing drives, installation of the new drives, commissioning service and customer training. Additionally all 47 drives are covered under the Danfoss DrivePro-tection program for the length of the contract. DrivePro-tection is a premium coverage program which not only covers defects and normal wear but also covers accidental drive damage such as lightning strikes or exposure to water.
“Our goal was to create a plan that would provide for a replacement and service path so the entire drive infrastructure could be managed as a maintenance expense,” Kreiss explains. “So I was glad Danfoss had the flexibility to customize SmartStep and DrivePro-tection to accommodate our budget and timetable.”
Customizing the upgrade plan and maintenance coverage
Normally, the SmartStep program is offered for three-, four-, or five-year periods. DrivePro-tection typically provides an extended warranty for new drives up to six years. But given St. Joseph’s budget constraints, the periods for both SmartStep and DrivePro-tection coverage were extended to 10 years.
“We preferred not to replace all 47 drives over a five-year period,” say Kreiss. “I appreciate Danfoss had the flexibility to create a custom 10-year program. Dividing 47 drives over a 10-year period, we’re replacing four or five drives a year. We select which drives to replace. If a drive fails ahead of schedule, we just bump back the drive that would have been replaced. With the DrivePro-tection coverage, Danfoss will replace additional drives if needed in a given year.” This kind of turnkey solution covering replacement and maintenance allows St. Joseph’s to continue using VFDs to save energy.
“There is an energy efficiency boost with the new drives,” adds Smith. “The old drives are 96 to 97 percent efficient. The new FC102 models are about 98 percent. In addition, the FC102 includes several energy optimizing benefits. Danfoss Automatic Motor Adaptation (AMA), Automatic Energy Optimization (AEO) and VVCPLUS Output Switching features maximize energy efficiency. Real-time energy monitoring incorporated in the FC102 can provide customers with payback information. The Danfoss MCT10 motion control tool available at no additional cost enables customers to link the drive to a PC for monitoring and printing reports. In Kreiss’ case, he took advantage of the built-in serial communications for Siemens Apogee® FLN to connect multiple drives with one communications cable for monitoring over the building management system.”
Danfoss SmartStep not only includes the latest advances in drive technology, but Smith emphasizes the real value of the program is the single point of contact for drives support and the price protection against inflation. SmartStep is an all inclusive solution for customers, providing DrivePro-tection to minimize disruption due to breakdowns, turn-key replacement and budgetary management.
As a turnkey solution, SmartStep includes retrofit kits that enable the drive to be adapted to the existing bypass, saving the cost of bypass replacement. Installation and commissioning work is performed by local Danfoss-authorized service partner companies. Reusing existing bypass enclosures often eliminates the expense of replacing control, line and motor wiring. In Kreiss’ case, he took advantage of the built-in serial communications for Siemens Apogee® FLN to connect multiple drives with one communications cable for monitoring over the building management system.
SmartStep can include Preventive Maintenance (PM) performed by a Danfoss partner. PM Service maximizes product longevity and optimizes performance. In this case, St Joseph’s opted to include training for their maintenance staff. Migrating to the latest generation of Danfoss drives provides the additional benefit of a single drive control to utilize.
“With the SmartStep program, we’re using money from the maintenance budget as opposed to making capital expenditures,” says Kreiss. “By covering every drive in the program with a service agreement that includes parts and onsite labor for the 10-year term, we get outstanding cost predictability.”
“Compared to traditional replacement and service plans, SmartStep and DrivePro-tection will probably save us 20 to 30 percent over the 10-year period,” concludes Kreiss. “Locking in the purchase and labor price for 47 drives at today’s prices, plus counting on predictable maintenance costs for ten years, have been a budgetary life-saver for St. Joseph’s Medical Center.”