It should come as no shock to hear that a plethora of equipment and systems exist to assure the delivery of safe, reliable electricity — there surely is a demand for it. In fact, the average U.S. household uses 920 kWh of electricity per month. Overall, 4,178,000,000 kWh of electricity is generated within the nation.
With the myriad of components that support our electricity-powered society, lingering issues with any given system can ultimately lead to alarmingly expensive and time-consuming solutions. However, maintenance testing can identify potential problem areas before their ill-effects can inexorably reach disastrous ends. The NETA standard for maintenance testing specifications, ANSI/NETA MTS-2019, exists to assure that tested electrical equipment and systems are operational.
The ANSI/NETA Standard for Maintenance Testing Specifications
The current edition of this American National Standard is ANSI/NETA MTS-2019: Standard For Maintenance Testing Specifications For Electrical Power Equipment & Systems. Developed for those responsible for the operation of existing electrical systems and equipment, this standard helps to guide workers in performing the necessary tests to assure that the equipment performs satisfactorily, and it also aids in minimizing downtime and maximizing life expectancy.
ANSI/NETA MTS-2019 is an expansive document, and the real meat of its guidance emerges in Chapter 7. This chapter offers a comprehensive series of tests, with specific information on the inspection and maintenance testing of electrical power equipment and systems. This includes tests for equipment such as switchgear assemblies, transformers, cables, switches, circuit-breakers, metal-enclosed busways, network protectors, protective relays, instrument transformers, metering devices, regulating apparatus, grounding systems, ground-fault protection systems, rotating machinery, motor control, direct-current systems, surge arrestors, capacitors, emergency systems, and fiber-optic cables.
Within the sections for these equipment types, there are typically four main bodies of information:
- A. Visual and Mechanical Inspection
- B. Electrical Tests
- C. Test Values – Visual and Mechanical
- D. Test Values – Electrical
Please note, however, that this document is not intended to explain how to test specific pieces of equipment or systems. Furthermore, some inspections have an associated value or result, and certain tests are assigned an optional classification. There are other factors to consider when making use of this standard, many of which are summarized in the following paragraph in ANSI/NETA MTS-2019:
“The guidance of an experienced testing professional should be sought when making decisions concerning the extent of testing. It is necessary to make an informed judgment for each particular system regarding how extensive a procedure is justified. The approach taken in these specifications is to present a comprehensive series of tests applicable to most industrial and larger commercial systems. In smaller systems, some of the tests can be deleted. In other cases, a number of the tests indicated as optional should be performed.”
Changes to ANSI/NETA MTS-2019
ANSI/NETA MTS-2019 revises the 2015 edition of the same American National Standard. As a substantial update, some of the changes made to the 2019 version include:
- The standard clarifies that its purpose is to identify necessary field tests and inspections for the evaluation of service-aged electrical equipment.
- Normative references were updated.
- Section 5.3, “Test Instrument Calibration,” was updated to reflect that that all test instruments should be calibrated within 12 months of the date of test.
- Section 5.4, “Test Report,” was updated to include device settings and inspection and test data.
- New section 5.5, “Test Decal,” was added to cover color-coding and other necessary information to include on a test decal affixed to the exterior of the equipment or equipment enclosure.
- Section 6.3, “Arc-Flash Hazard Analysis,” from ANSI/NETA MTS-2015 was renamed “Incident Energy Analysis.”
- For the visual and mechanical inspection procedure for switchgear, switchboard, and panelboard assemblies, a new step was added to verify that wiring connections are tight and wiring is secure. In addition, for electrical tests, steps were added to perform online partial-discharge survey and system function tests.
- New optional step was added during electrical tests for transformers, dry type, air-cooled-large, to perform online partial-discharge survey on winding rated higher than 600 volts.
- New optional step was added during electrical tests for transformers, liquid-filled, to perform sweep frequency response analysis.
- New optional step was added during electrical tests for metal-closed busways and switches, air, medium-voltage, metal-enclosed, to perform online partial-discharge survey.
- New step for electrical test values for various switch types to investigate fuse resistance values that deviate from each other by an amount specified in the standard.
However, these are only some of the changes made to the ANSI/NETA MTS-2019 standard. Users can see where an insertion, deletion, or alteration of text has taken place, as these areas are marked with a black vertical line to the left.
ANSI/NETA MTS-2019: Standard For Maintenance Testing Specifications For Electrical Power Equipment & Systems is available on the ANSI Webstore.