Earth-Leakage Relay protects VFDs from 0-15,000 Hz.
May 3, 2012 -
Able to detect ground current, even in resistance-grounded electrical systems, EL731 AC/DC Sensitive Earth-Leakage Relay is equally useful for AC, mixed AC/DC, and DC systems, including low-voltage 6-pulse variable frequency drives used on motors up to 250 hp. Model EL731 can be installed in place of existing ground fault relay without replacing current transformer. Unit can protect variety of applications including conveyor belts, cranes, compressors, pumps, and mixers.
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|Original Press release |
800 E. Northwest Hwy.
Des Plaines, IL, 60016
Littelfuse Introduces the EL731 AC/DC Sensitive Earth-Leakage Relay
First product on the market to provide complete range of ground-fault protection in variable speed drives from 0 to 15000 Hz in one device
CHICAGO, IL - Littelfuse, Inc., a leading expert in electrical safety, power distribution and power control products, today announced its new EL731 AC/DC Sensitive Earth-Leakage Relay, which can detect ground currents-even in resistance-grounded electrical systems-all the way down to 0 Hz. This makes it ideal for protecting variable-frequency drives (VFDs) that may operate at low speeds, during which AC current approaches DC.
The EL731 relay provides complete range of ground-fault protection in VFDs from 0 to 15000 Hz in one device, saving cost and panel space compared to other relays.
Unlike any relay previously available, the EL731 uses a patented approach that enables the relay to detect the location of ground faults and makes it equally useful for AC, mixed AC/DC, and DC systems, including low-voltage 6-pulse VFDs commonly used on motors up to 250 hp. It can reliably protect a variety of applications including conveyor belts, cranes, compressors, pumps and mixers found in demanding environments such as mining, oil sands operations, chemical plants, food processing, and other industrial facilities.
"This is the first relay to adequately address the common challenge of detecting ground faults in VFDs operating at low speed," said Tony Locker, P.E., Littelfuse Product Manager.
The new relay is ideal for protecting VFDs operating in resistance-grounded electrical systems, which are growing in popularity because of their ability to reduce arc-flash hazards. The on-board ground-fault protection that comes with VFDs is generally not sensitive enough to detect a ground fault in resistance-grounded systems.
The EL731 can be installed in place of an existing ground fault relay without replacing the current transformer. Two CTs are required for the entire frequency range, or one CT can be used for only low- or high-frequency detection. The relay has a temperature input, metering capabilities, password protected alarm and trip settings. Ethernet communications port is optional.
For more information on the EL731 visit www.littelfuse.com/acdc
For more information on Littelfuse Protection Relay Products, or any of Littelfuse's circuit protection devices, visit the Littelfuse protection relay website at www.littelfuse.com/ProtectionRelays or call our technical support line at 1-800-832-3873.
Founded in 1927, Littelfuse, Inc., the worldwide leader in circuit protection, offers the industry's broadest and deepest portfolio of circuit protection products and solutions. Littelfuse devices protect products in virtually every market that uses electrical energy, from consumer electronics to automobiles to industrial equipment. In addition to its Chicago, Illinois, world headquarters, Littelfuse has more than 30 sales, distribution, manufacturing and engineering facilities in the Americas, Europe and Asia. Technologies offered by Littelfuse include Fuses; Gas Discharge Tubes (GDTs); Positive Temperature Coefficient Devices (PTCs); Protection Relays; PulseGuard® ESD Suppressors; SIDACtor® Devices; Silicon Protection Arrays(SPA(TM)); Switching Thyristors; TVS Diodes and Varistors. The company also offers a comprehensive line of highly reliable Electromechanical and Electronic Switch and Control Devices for commercial and specialty vehicles, as well as underground Power Distribution Centers for safe control and distribution of electricity in mining operations.
For more information, please visit the Littefuse Web site at www.littelfuse.com.