Test Methods Comparison NEMA MW1000 VS IEC 60851 – Enameled Wire
The NEMA MW 1000 standard is developed by the National Electrical Manufacturers Association and is widely used in North America. It specifies the requirements for magnet wire, including various tests to ensure quality and performance.
The IEC 60851 series, developed by the International Electrotechnical Commission, is internationally recognized and specifies test procedures for winding wires, including enameled wires.
| NEMA OR IEC TEST | Comparison to IEC Method | Comments | ||
| Technically | Minor | Major | ||
| Equivalent | Difference | Difference | ||
| DIMENSIONS | X (?) | MEASURING FORCES DIFFERENT; NUMBER AND LOCATION OF MESUREMENTS NOT THE SAME.. | ||
| ADHERENCE & FLEXIBILITY | X | X | ‘RECTANGULAR WIRES TESTED WITH OTHER METHOD; MANDREL WINDING RATES LISTED IN 60851, | |
| (Rect.) | NOT IN NEMA; 3 TO 5 TESTS PER SAMPLE REQUIRED IN 60851; “ADHERENCE TEST” ONLY IN 60851. “JERK TEST” NOT IN NEMA. | |||
| ELONGATION | X | SAMPLE LENGTH SLIGHTLY DIFFERENT: NEMA 254 mm, IEC 200 TO 250 mm | ||
| HEAT SHOCK | X (Rect.) | X (Round) | TOTAL SAMPLE ELONGATION DIFFERENT: EXAM. MAGNIFICATION LOWER IN NEMA; MANDREL WRAP USED IN NEMA UP TO 10 AWG | |
| RECTANGULAR WIRE BENT FLATWISE TO 180 DEGREES IN IEC METHOD; . | ||||
| SPRINGBACK | X | X | GROOVES ALLOWED IN MANDRELS IN 60851 TESTER. LOADS USED ARE DIFFERENT AND NEED TO BE COMPARED. | |
| (>AWG 14) | (< AWG 14) | |||
| DIELECTRIC BREAKDOWN | X | X | X | RATE OF VOLTGE RISE DIFFERENT; LARGE ROUND (> 10 AWG, 2.5 mm) |
| (<AWG 38) | (AWG 37-10) | (Rect.) | TESTED USING FOIL ELECTRODE IN NEMA AND SHOT IN IEC. RECT. TESTED DIFFERENTLY; 5 SPECIMENS REQUIRED PER TEST. | |
| HIGH-VOLTAGE CONTINUITY | X | USE OF CONDUCTIVE BRUSH ELECTRODES ELECTRODES RECOGNIZED IN NEMA AND IEC STANDARDS | ||
| LOW- VOLTAGE CONTINUITY | X | PRIMARY DIFFERENCE IS CONDUCTIVE MEDIUM: MERCURY VERSUS SODIUM SULFATE. | ||
| COMPLETENESS OF CURE | X (?) | ‘NO TEST IN IEC 60851 FOR POLYVINYL ACETAL (TOLUENE-ETHANOL BOIL METHOD); DIELECTRIC LOSS TANGENT TEST (TEST # 19) | ||
| ‘IS NOT RESTRICTED TO POLYIMIDE MATERIALS IN IEC. | ||||
| SOLDERABILITY | X | TWISTING OF 8 STRANDS REQUIRED FOR < 0.05 mm (AWG 44) IN IEC; TWISTING REQUIRED FOR WIRES < 0.02 mm (AWG 52) IN NEMA. | ||
| IMMERSION DEPTHS DIFFERENT, 32 VERSUS 20 mm; IEC ALLOWS FOR TESTING BUNCHED WIRE, NOT IN NEMA. | ||||
| THERMOPLASTIC FLOW | X | DIFFERENCE IN PREHEATING, IEC – 1 OR 2 MIN., NEMA APPROXIMATELY 10 MIN. WITH TEMPERATURE RISING FROM 55 DEGRESS BELOW | ||
| (CUT-THOURGH) | THE EXPECTED TEMPERATURE. | |||
| SOLUBILITY | X | NEAREST EQUIVALENT TEST IS “SOLVENT TEST”, CLAUSE 3.1 OF 60851-4. | ||
| DIELECTRIC STRENGTH AT |
(<AWG 38) |
X | X | RATE OF VOLTAGE RISE DIFFERENT; LARGE ROUND (> 10 AWG, 2.5 mm) TESTED USING FOIL ELECTRODE IN NEMA |
| RATED TEMPERATURE | (AWG 37-10) | (Rect.) | AND SHOT IN IEC. RECT. TESTED DIFFERENTLY; 5 SPECIMENS REQUIRED PER TEST. | |
| TRANSFORMER OIL RESISTANCE | X | TESTS WERE DEVELOPED AND MODIFIED IN PARALLEL WORK IN IEC AND NEMA. | ||
| AND HYDROLYTIC STABILITY | ||||
| REFREIGERANT EXTRACTION | X | ONE OF TWO TESTS INCLUDED UNDER “RESISTANCE TO REFRIGERANTS”, CLAUSE 4, TEST 16 OF 60851-4. | ||
| RETAINED DIELECTRIC AFTER | X | VERSIONS IN IEC AND NEMA VERSION NEARLY IDENTICAL. | ||
| RFRIGERANT EXTRACTION | ||||
| BOND | X | NEMA TESTS ONLY THREE SIZES OF WHICH ONLY AWG 36 (0.125 mm) IS TESTED SAME METHOD AS IEC; ELEVATED TEMPERATURE. | ||
| BOND RETENTION (STRENGTH) NOT SIMILAR. TWISTED COIL METHOD IS NOT IN NEMA PROCEDURE; SOLVENT BONDING METHOD | ||||
| THERMAL ENDURANCE | X | IEC 60172 = ASTM D2307. | ||
| SCRAPE RESISTANCE | X | TESTS IDENTICAL EXCEPT FOR VOLTAGE IN TEST CIRCUIT: 7.5 VERSUS 6.5. | ||
| LOSS OF MASS | N/A | TEST ONLY IN IEC 60851-6 | ||
| ELECTRICAL RESISTANCE | N/A | NO EQUIVALENT TEST IN NEMA. (FOUND IN ASTM TEST METHODS.) | ||
| LAP SHEAR BOND STRENGTH | X | IEC AND NEMA VERSIONS ARE TECHNICALLY EQUIVALENT | ||
| NOTE: “EQUIVALENT” MEANS THAT TESTING METHODS ARE ESSENTIALLY THE SAME; “MINOR DIFFERENCE” MEANS THAT PROCEDURE DIFFERENCES PROPABLY DO NOT AFFECT TEST RESULTS; |
| “MAJOR DIFFERENCE” MEANS THAT PROCEDURES ARE DIFFERENT ENOUGHT TO AFFECT RESULTS. |
Both NEMA MW 1000 and IEC 60851 provide comprehensive guidelines for testing enameled wire, ensuring high-quality and reliable products. While they share many similarities, the differences in test details and conditions reflect their regional focuses and target markets. Manufacturers often need to adhere to both standards to ensure their products meet the diverse requirements of global markets.
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