AVO is hitting the road! Come visit us from May 21-23 at booth 1028 in Orlando, Florida at the AFPM Reliability & Maintenance Conference.
We’ll be at the Marriott Orlando Word Center Resort & Convention Center ready to answer your questions and inform you about our courses, on-site training, and Arc Flash Hazard Analysis services. To set up an appointment with us while we are in Florida, contact us at (877) 832-5234, or at info@avotraining.com. We look forward to seeing you!
Enhance your system reliability with Megger’s updated SMRT series.
As utilities and manufacturers get smarter equipment, a smarter grid and smarter system components, Megger continues to listen to the industry and evolve the company’s SMRT relay testing equipment to adapt to immediate needs.
Already a rugged, reliable tester, the SMRT system now includes firmware and software upgrades for an easier operator experience.
The SMRT system (SMRT1, SMRT36, and SMRT410) now offers overall adaptations as well as a devilish look at the firmware details, which make all the difference out in the field. In the all-important details category, Megger has adapted the SMRT36 current channels in a “push-push-push” series configuration that will provide up to 150 volts at four amps for testing high impedance loads, while improving general calibration at test currents down to 100 mA. And, Megger has added communications support for the SMRT410 double current generator (DIGEN) as well as the voltage-only generator (VGEN), making the SMRT series more interoperable and cost-effective.
Megger didn’t just polish the firmware in this update. The system’s integral interface also received a push up the evolutionary ladder.
The companion interface to our SMRT system received some requested upgrades as well, especially in the area of impedance relays. The revolutionary SMRT Smart Touch View Interface (STVI) now has improved click-on-fault functions for testing impedance relays. The operator can now import RIO files to the impedance relay selection screen. Another devilish detail is a sixth zone for impedance relays has been added within the selection window. The impedance-relay-setting screen, additionally, offers zone blinders within the updated STVI software. Megger’s modernized STVI also provides CT graphics for CT polarity connections, an ohms-per-loop and ohms-per-phase selection button, and separate zone timer settings for each fault type.
Listening to our users and industry insiders brought real change to the STVI with a new sequencer test screen with end-to-end dynamic test capabilities. All of these changes make the STVI one of the easiest-to-use interfaces available on the market today and adds to the functionality of the SMRT system.
Of course, even without these upgrades, the STVI offers a bevy of benefits to the operator of SMRT testers from its high-resolution color touch screen, which reduces errors, to its intuitive operation, which requires no special training for manual testing. The STVI is an essential component in the SMRT system, offering automatic ramp, pulse ramp and pulse ramp binary search options. More time curves from a larger variety of overcurrent relay manufacturers have been added to the hundreds of built-in time curves that are already provided. The STVI includes downloadable results that operators can transfer onto a thumb drive quickly and easily for NERC PRC-005-2 standard requirements.
For those times when you must have accurate readings, pinpoint accuracy and details, rely on SMRT relay testing with Megger. Click here to learn more about these amazing products.
Protective relays plan an integral part in the prevention of electrical hazards and to equipment and personnel. But these devices only operate during an abnormal electric power system condition, so it is difficult to determine if they are prepared to operate correctly. ANSI/NFPA70B states that the only way to assure correct operation is through a comprehensive inspection, maintenance and testing program.
NETA reports show that there is an average of 12% failure rates on protective relays tested. The typical cycle for maintenance and testing, as recommended by ANSI/NFPA70B is one to three years, but most manufacturers recommend an annual testing cycle.
Which tests to you run? There are different tests for different relays. NETA procedures include:
Ensuring you or your maintenance personnel are knowledgeable in these areas is essential to maintaining safety at your facility. The AVO Training Institute offers a number of classes including Protective Relay Maintenance courses and Microprocessor-Based Relay Testing courses to help address these needs. Contact us today to learn more.
We are proud to announce courses in North Carolina beginning in 2013. Courses include:
Visit our website for details. We plan on expanding throughout the year, so be looking for updates as we add new courses.
Class Schedule:
Protective Relay Maintenance, Basic – Feb. 4 – 8, 2013
Conducted at the Wake Electric Membership Corp.
228 Park Ave., Youngsville, NC 27596
For more information or to sign up, contact Paul Jackson at 214-330-3527, paul.jackson@avotraining.com .
Ground Fault Overcurrent Relays – Residual vs. Zero Sequence
There seems to be some confusion regarding the distinction between residually connected ground fault protective relays and zero sequence ground fault protection devices. As I understand this distinction, based in part on IEEE C37.2-2008 “IEEE Standard for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations”, it all has to do with how the relay is connected and what the relay responds to.
If the relay is connected in the residual (neutral return) path of the phase CT’s or the operating quantity is internally derived from the relay three phase current inputs the relay designation should contain the suffix “N” i.e. 50N, 51N, 67N.
If the relay is connected to a “ground sensor” CT or is connected to sensing in the path to ground the suffix should be “G” i.e. 50G, 51G.
The distinction between the two approaches is simply whether the relay will respond to only ground fault (zero sequence) current (suffix “G”) or the relay will respond to residual (unbalance phase) current whether caused by a ground fault or load unbalance current (suffix “N”).
All About AmpsVoltsOhms 