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Silence of the Drives - Motor Drive Manufacturer Highlights from AHR 2009
Motor Drive Manufacturers Highlight Low Harmonics & Network Interfaces
By Bill Lydon - Contributing Editor
Variable Frequency Drive suppliers at the 2009 AHR Expo demonstrated quieter drives, network interfaces, and other improvements. Variable Frequency Drives (VFD) are now widely used in HVAC systems as an accepted method to improve efficiency and comfort by modulating air and fluid flow to save energy. Products demonstrated focused on reducing physical size, increasing efficiency, network interfaces, and lowering electrical noise.
Electrical noise from the wide use of variable speed drives has created an industry of companies selling electrical filters to protect other electrical equipment. The protection of computers in particular has become important to eliminate operating faults and damage. Drives that create less electrical noise attack the problem at the source.
There is an increasing concern among end users and power companies about the harmful effects of harmonics. Harmonic distortion may disturb or even damage sensitive equipment connected in the same environment. Harmonic standards are becoming stricter and there is a growing demand for low harmonic solutions. It takes time for users and specifiers to learn and understand new technology before adopting it, and low harmonic drives are no exception. Suppliers told me that low harmonic drives are now being specified about 30% of the time in projects.
In particular, suppliers are addressing the IEEE (Institute of Electrical and Electronics Engineers) guidelines, IEEE 519-1992, for applying limits to the level of harmonic distortion that a utility customer may inject into the power system. The guidelines pertain to percent harmonic current and voltage distortion at the Point of Common Coupling (PCC), which is defined as the point where the utility connects to multiple customers. View IEEE Guidelines.
What are Harmonics anyway?
Any distorted voltage and current waveform that deviates from the ideal sinusoidal waveform presents the potential to harm electrical components, resulting in costly repairs and equipment downtime. Non-linear loads connected to the electrical supply in industrial and commercial facilities insert harmonics (waveform distortions) on the power distribution system. Common non-linear loads include solid state motor soft starters, variable speed drives, computers, electronic lighting, and uninterruptible power supplies.
The impact of harmonic distortion can appear in many ways: it can cause distribution transformers and supply cables to overheat, resulting in insulation breakdown and failure; electronic displays and lighting may flicker; nuisance tripping of circuit breakers is possible; and damage can occur to electronic equipment, and may even distort readings provided by metering equipment.
The effects of harmonic distortion are not limited to the facilities where electrical equipment is installed. Situations where electrical equipment is installed in residential areas (pumping stations, waste water treatment plans, cooling towers, and HVAC systems) present the potential for equipment in residential and commercial buildings to be impacted and even damaged.
AHR 2009 Drive Products Demonstrated
These vendors have been refining their offerings for the HVAC industry over a number of years.
Yaskawa Electric America, Inc.
Yaskawa Electric America demonstrated the AC7 Matrix Converter that produces a direct AC/AC conversion without the need for a DC link circuit. The AC7 converts AC input voltage into variable AC output voltage to provide efficient operation. The AC7 Matrix Converter uses an array of semiconductors known as insulated gate bipolar transistors (IGBTs) to connect the three phases of supply directly to the motor. By correctly sequencing the operation of these solid state switches, the voltage and frequency of the output to the motor can be precisely controlled. The input current waveforms are sinusoidal, allowing for a dramatic decrease in current harmonics. Yaskawa claims there is 82% less distortion with an AC7 Matrix Converter compared to that of a conventional general-purpose AC drive, resulting in less than 7% distortion with the AC7.
Yaskawa AC7 Drive
The AC7 Matrix Converter is significantly smaller than a traditional AC drive package with equivalent harmonic filtering. The AC7 has a 45% smaller installation footprint, has 70% fewer wires, and is 62% lighter than a conventional AC drive with required harmonic mitigation peripherals.
Yaskawa also demonstrated the E7N Narrow Bypass Package for higher horsepower ratings that is plenum-rated for commercial HVAC applications. The E7N Narrow Bypass Package is designed for ease of mounting in very narrow locations and includes touchpad controls, and a range of control, communication, and power options. Communications options are LonWorks Serial and BACnet Serial.
Yaskawa E7N Narrow Bypass
ABB
ABB demonstrated their ULH (Ultra Low Harmonic) drives with a clever display, and gave attendees “ABB Harmonicas” to punctuate the harmonic theme. ABB Ultra-Low Harmonic (ULH) ACS800 drives do not require a multi-pulse transformer, external filters or other additional equipment for minimizing harmonics. The drive features an active converter with Direct Torque Control (DTC) to eliminate low-order harmonics. The ULH drive is available in both wall-mount and enclosed cabinet-built versions (depending on ratings and options selected).
ABB also featured the E-Clipse Bypass that allows building managers to keep motors in constant-speed operation when drives need maintenance.
ABB introduced a LonWorks interface for Low Voltage Drives, the FLON-01 LonWorks Adapter module for the company’s E-Clipse Bypass option for the ACH550 drive for HVAC applications. The option adapter mounts to the E-Clipse Bypass, allowing serial control and / or monitoring of the E-Clipse Bypass and ACH550 drive. Both the E-Clipse Bypass and ACH550 are given a unique node ID, allowing the building automation controller a network interface to the bypass, even if the ACH550 is out for maintenance or service.
ABB provides LonMark® certified adapter for interoperable LonWorks connectivity.
In addition, the interface supports pass-through I/O, allowing integrators to use the E-Clipse Bypass and ACH550 drive’s digital and analog inputs/outputs as free I/O points in their system. These I/O points can be used for monitoring and/or control of external devices such as dampers that may not be directly related to the E-Clipse Bypass HVAC application.
This new adapter makes the E-Clipse Bypass option for the ACH550 the first (and currently the only) VFD bypass to be LonMark product certified. For a listing of all ABB products that are LonMark product certified, visit the LonMark Certified Product Catalogue at http://www.lonmark.org/
EATON
Eaton featured drives, bypass, and disconnect products.
HVX9000 IntelliPass & IntelliDisconnectThe ultra-compact IntelliPass and IntelliDiconnect designed for the HVAC industry supports N2 Modbus, APOGEE, BACNET, and LonWorks communications interface protocols. The IntelliPass is an intelligent drive integrated with a bypass configuration and Eaton’s Intelligent Technologies (IT) contactors. The IntelliDisconnect drive combines a drive with an integrated circuit breaker disconnect. These products have an onboard start-up wizard to assist in start-up and commissioning.Available in NEMA 1, 12, 3R or customized NEMA 4X enclosures, Eaton’s HVAC drives are customized to specific requirements. Construction features allow for easy installation, reliable operation and serviceability. Software parameters utilize engineering units common to the HVAC industry. Both offer true, full network connectivity. The IntelliPass and IntelliDisconnect are 65AIC and UL508C approved for original equipment manufacturer (OEM) quality.CFX9000 Clean Power DrivesThe CFX9000 Clean Power Drives use tuned passive filters to reduce line harmonics at the drive input terminals. With a single enclosure for both drive and filter, the CFX9000 reduces field wiring and enables convenient bypass installation. Designed to meet the IEEE 519-1992 requirements for harmonic distortion, the CFX9000 is used for small and midsize drive applications where harmonics are a concern. In addition to reducing harmonic distortion, the CFX9000 drive also delivers True Power Factor - it prevents transformer overheating and overloading of breakers and feeders, which enables the application of adjustable frequency drives on generators and other high impedance power systems. The CFX9000 is offered in both standard and modified standard enclosed options, as well as custom engineered options.
Mitsubishi Electric Automation
Mitsubishi Electric Automation, Inc., introduced a new Pow-R-Gate HVAC bypass controller for applications that require low-harmonics on their electrical systems. The Pow-R-Gate relies on 18-pluse variable-frequency technology and is designed to meet IEEE 519-192 requirements at the input terminals. The Pow-R-Gate is suitable for NEMA 12 ventilated enclosures. The platform is rated up to 800HP at 460V systems. The platform offers a multifunction programming and display unit — the average set up is eight parameters. Operators can select either manual or automatic bypass. A three-contactor bypass configuration, built-in PID control, and disconnect are all standard features on all new Pow-R-Gates.
This platform offers RS485 and Modbus® RTU as standard network communications and one of the broadest set of options available today for intelligent networking. These options include Ethernet/IPTM, LonWorks®, Siemens® FLN, Modbus® TCP/IP, Metasys® N2, and BACnet® IP or BACnet® MSTP.