ANSI/NETA MTS-2023: Maintenance Testing Specifications For Electrical Power Equipment

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, 4,243,000,000 kWh of electricity was generated within the nation in 2022.

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-2023, 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-2023: 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-2023 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-2023:

“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-2023

ANSI/NETA MTS-2023 revises the 2019 edition of the same American National Standard. As a substantial update, some of the changes made to the 2023 version include:

• Former section 7.24.1 was moved to 7.23, “Communication,” and expanded.
• Former section 7.24.2 was moved to 7.24.1, “Automatic Circuit Reclosers and Line Sectionalizers, Automatic Circuit Reclosers, Oil/Vacuum,” and expanded.
• References were updates.
• Section 3 was expanded to include qualifications of both the testing organization and personnel.
• In Section 4, “Division of Responsibility,” the user was changed to the owner’s representative.
• CSA Z462, Workplace Electrical Safety, was added to the list of workplace safety practices.
• Short-circuit studies are now to be performed in accordance with IEEE 3002.3-2018: IEEE Recommended Practice For Conducting Short-Circuit Studies And Analysis Of Industrial And Commercial Power Systems.
• Load-flow studies are now to be performed in accordance with IEEE 3002.2-2018: IEEE Standard For Recommended Practice For Conducting Load-Flow Studies And Analysis Of Industrial And Commercial Power Systems.
• Harmonic-flow studies are now to be performed in accordance with IEEE 3002.8-2018: IEEE Recommended Practice For Conducting Harmonic Studies And Analysis Of Industrial And Commercial Power Systems.

However, these are only some of the changes made to the ANSI/NETA MTS-2023 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-2023: Standard For Maintenance Testing Specifications For Electrical Power Equipment & Systems is available on the ANSI Webstore.

Changes to ANSI/NETA MTS-2019

The 2019 edition of this standard was also a significant revision. To assist past users of this American National Standard, we’ve listed some of the changes made between the 2015 and 2019 versions here:

• 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.