Application Update: A/C controls handle the heat of a growing shop floor
YH America Inc. (YHA) hums along producing automotive fluid conveying products, sealants, and both power steering and brake components, in Bluegrass Country amid stables breeding champions. After lugging through a historical low, the automotive sector is picking up speed and the heat is on—literally—for Versailles, KY-based YHA.
“Production dropped in 2009, and we weren’t at full capacity,” explained John Martin, electrical controls specialist at YHA. Now, “it’s back to full-speed, and we’ve added 30 new tube-forming machines, each with its own 20-hp hydraulic pump motor.” Adding 600 hp of additional heat to the burgeoning 120,000-sq-ft production facility meant YHA had to quickly find a way to keep 280 employees spread among two shifts cool.
Syncing the setpoints
To cope, YHA relied on 22 roof-mounted air conditioner units, each controlled by a lockbox-enclosed, programmable thermostat under each duct. Seemingly simple, this proved disruptive.
“The programmable thermostats did not have battery backups,” Martin explained. “So, if we had a power flicker—even one that didn’t shut off our manufacturing equipment—we’d have to readjust every A/C unit. It seemed like we never had all those setpoints synced.”
Staff scrambled to check each thermostat and feel air flowing from each duct. Then, there were other variables: Was a unit low on coolant? Did its compressor kick on? Compounding this was reliance on humans for efficiency. Were units idled properly at shift’s end? Dialed back six degrees to 86°F for the weekend? YHA needed a unified way to monitor and control each duct, prompting removal of stock thermostats from each rooftop A/C unit.
Martin chose Pro-Face HMI (Saline, MI), Air Hydro Power Inc. (Louisville, KY), and Wago Corp. (Milwaukee) to assist with the design of a comprehensive A/C control system. This led to 22 Wago PFCs (and I/O modules), a Wago power supply, and Wago Topjob terminal blocks to tie it all together. To ensure maximum efficiency, YHA performed the entire project, from installing the enclosures to control programming, entirely in-house. Routine A/C service and repairs are performed by contractors.
“We installed Wago IP65 enclosures on each major support beam under the ducts,” he explained, also using 22 Wago 750-841 Ethernet TCP/IP Programmable Fieldbus Controllers (PFCs) and associated I/O, and for temperature control, Wago’s 750-512 relay output modules were used.
YHA’s A/Cs move heated/cooled air in two stages: stage 1 (2 compressors) and stage 2 (all 4 compressors). Wago’s 750-461 2-channel RTD inputs were paired with sensors that monitor temperature at each duct and at each rooftop unit zone via second RTD input. That helped because the facility, essentially one large area, is split into zone 1 (open production floor and break rooms served by 16 A/C units) and zone 2 (offices served by six A/C units).
Coordinating coverage between zones are two Wago 750-871 Ethernet TCP/IP Programmable Fieldbus Controllers. Each PFC ensures the A/Cs reliably engage night or comfort modes as programmed. The PFCs were also insurance, “functioning as a backup for each A/C unit’s 750-841 PFC. So, if we have an outage, the 750-871 Ethernet PFC ‘directors,’ take control,” Martin said. That flexibility wouldn’t have been available, Martin suggested, with I/O systems built around one master controller.
YHA selected an 8-inch Pro-Face HMI to tie into the Wago PFC Web browsers for real-time system feedback on operating status, stage (such as cool 1/cool 2 or heat 1/heat 2), and temperatures for the 22 ducts. The system allows remote access.
“Head of maintenance or floor personnel can walk by and get all that info at a glance,” Martin said. “Is a blue LED blinking? Is a unit calling for cool? If a duct’s temp is constant despite a programmed change, we call our contractors. This is really great for diagnostics and, if necessary, troubleshooting.”
Martin’s primary role at YHA is in control design, machine modifications, and manufacturing engineering. He learned CoDeSys programming software, using one cooling and one heating output function block and additional function blocks for two-stage heating and cooling.
The new A/C control system helped YHA meet its commitment to the ISO 14001 Environmental Management System. YHA personnel meet monthly to trim waste and consumption and advance recycling. And the controls reduced A/C costs.
“In the past, we’ve just allotted $10,000/month in the summer just for A/C, based on last six or seven years,” Martin admitted. But that’s just a ‘bucket;’ we really don’t know precise HVAC energy usage and associated costs.”
Eight Wago 750-493 3-Phase Power Measurement Modules will measure actual HVAC kilowatthours used, a move advocated by Martin and YHA President Ed Behn.
“Right now, our initial energy goal with the HVAC control system was to save $20,000 annually,” Martin said. “Return on investment on the HVAC system is an estimated two years; however, this may change when the 750-493 comes online and provides feedback.”
As of May 2010, Martin estimated energy use at slightly below YHA’s historical baseline before HVAC automation, despite the additional 600 hp worth of heat. Data will assist with future expansion. When equipment is added, YHA can measure the impact. Beyond enhancing decision-making, the data will also assist with troubleshooting.
Beyond accounting, “if a machine starts using more electricity, we can identify it as an ‘energy hog,’ ” then, “we can change motors or look at other modifications.”
Although power measurement modules are not yet installed, YHA is performing more modifications. Each A/C unit is equipped with a sensor-driven economizer that minimizes compressor usage by drawing in and moving cool air via fan if ambient temperatures and humidity permit. However, stock sensors were reluctant to rely on fans alone. So, Martin is tying them to the Wago-driven A/C controls, and expecting greater savings from more fan-only cooling.
As the A/C automation project nears completion, Martin noted: “HVAC is a big energy user, so my advice is to install metering first. Then, you can make the best decision for allocation of resources.”
The automotive sector is accelerating into a future wrought with fluctuating consumer preferences and increasingly stringent emission and economy guidelines. A more comfortable workforce, cooler machines, and lower energy costs will help YHA keep pace.
– Paul Garcia is creative/technical writer, Wago Corp., www.wago.com.