The Changing Face of HVAC Motor Control

January 29, 2016 By Carl Weinschenk

hvac_motorThe drive toward energy efficiency is changing just about everything a facility manager has to track – including HVAC motor controls.

The use of variable frequency drives (VFDs) to control motors are a common approach to powering HVAC systems. A VFD, according to VFD.com, is a motor controller that uses frequency and voltage to adjust the speed of the unit.

The overall VFD market – which goes far beyond HVAC – is changing and growing rapidly. Technavio predicts that the sector, which is taking market share from mechanical and hydraulic motors – will experience a compound an annual growth rate (CAGR) of 8 percent through 2020. Another report – this one released earlier this month by Frost & Sullivan – suggested that the evolution is dramatic:

Homeowners and end users from the construction and commercial verticals are increasingly seeking out technologically innovative solutions as replacement products. Consequently, HVAC equipment suppliers are diversifying their portfolios with respect to system design and technology.

The design changes were discussed this week by McGuire Engineering’s John Yoon at Consulting-Specifying Engineer. Yoon’s piece is a highly technical. The bottom line, however, is that facility managers – or the on-staff or outside people who advise them on difficult engineering-based buying decisions – should not underestimate the importance of these changes.

The move to energy efficient operations is made real by legislators and regulators in changes to codes and standards. Those who are charged with designing and installing HVAC systems should keep abreast of these changes. Writes Yoon:

Design engineers are often caught off guard by energy-code changes. In many cases, the changes seem to add unjustified expense and complexity to HVAC systems that worked fine before. While engineers usually focus on specific aspects of designs, there is a need to take a step back to get a broader perspective on the external influences that will continue to push the designs toward increased energy efficiency.

The world of HVAC motors is not a simple one. There are several concerns, according to Dave Morse, the Director of Sales and Operations for Delta Product’s Industrial Automation Group. “Some systems may use variable speed blowers or constant speed blowers with variable dampers,” he told Energy Manager Today. “Many HVAC systems use Induction motors, yet others are using Electrically Commutated Motors (ECM) with embedded controls. There are also needs for Plenum rating for use in the duct, or special features such as Purge mode and BACnet communication.  To help make the facility managers workload easier, it is always better to find a VFD that incorporates many of these features into one drive.”

The details are, of course, quite complex. At the highest level, however, the basic point is simple: People in charge of HVAC systems must educate themselves.

Yoon provides the overview on how things are changing over time. Within that context, there have been several announcements during the past few weeks on HVAC power and related issues.

  • Delta used the Air Conditioning, Heating and Refrigeration Expo at the Orange County Convention Center in Orlando to introduce the NEMA 1 stacked bypass system. The company said in a press release before the show that the device is designed for drop-in HVAC applications. It offers the capabilities of the company’s CP2000 series VFDs, hand-off-auto switch capabilities and other features.
  • EC Fans & Drives, which is a division of Epec Engineered Technologies, used the same show to introduce the EConomy and the EXRi50 motors. The motors, the press release says, have finished six-month beta tests with several companies. The EXRi50 has a slim profile that can be deploy in areas too small for many current motors. The EConomy is a single speed, single direction entry level motor with an output power of 1 to 16 watts. The EXRi50 is a single speed, single direct motor with EC fan assembly. It is available as a fan pack with an integrated fan ring.
  • While not a motor itself, Fluke’s new 902 FC True-rms HVAC Clamp Meter tests HVAC systems, which is deeply related to motors and their operation. The press release says that the meter is rated for CAT III and CAT IV (600V and 300 volts, respectively) and performs what the release calls all the essential measurement of an HVAC system. The 902 FC can send measurements to a mobile device for subsequent analysis.

Energy efficiency is a goal and a high level concept. At the end of the day, it only becomes real when it codified and companies produce gear that fulfill those mandates. That seems to be happening in the realm of HVAC powering.

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