PT. BINTANG LESTARI PERSADA
Electro Mechanical Workshop
ELECTRO MOTOR TESTING PROCEDURE AC LOW – MEDIUM VOLTAGE 1. Record name plate and perform visual inspection and reporting. 1.1. Part listing (terminal, fan, pulley / coupling, thermostat, etc). 1.2. Rotate shaft with hand (noise, jammed part, foreign object). 1.3. Cooling device (damage, crack, leak) 1.4. Complete condition 2. Perform Insulation Resistance test. 2.1. The recommended insulation resistance to ground, R min, when measure at or corrected to 40° C is given by :
R min : n + 1, in Megohm. When n is the rated machine potential in kilovolt. A 500V Megohmmeter is suitable for testing of machine rated up to 2400V. above that voltage, a 1000V Megohmmeter is recommended. Test voltage should be applied for one minutes ( ref IEEE std. 43). 2.2. If test are pass, continue to step 3 2.3. If test are fail, follow this step : 2.3.1.Dismantling electro motor to perform complete inspection. 2.3.2.Measuring Insulation resistance of Stator after rotor has been removed 2.3.3.Perform inspection and documented for evidence of damage or degradation such as : 1. Puffiness, cracking, separation or discoloration as indication of thermal aging. 2. Contamination of coil and connection surface. 3. Abrasion or other mechanical stresses. 4. Evidence of partial discharge (Corona). 5. Loose wedge, filler, ties, banding, or surge rings. 6. Fretting of supports, Bracing, or Crossings (an indication of looseness and movement). ( ref IEEE std. 432 sec. 5. ) 2.3.4.Turn to Turn resistance or phase balance test (must equal, tolerance is ± 0,3 Ω). 2.3.5.Surge test wave form Using wave diagram as describe below to analyze winding condition. BAKER Surge Winding Analyzer ( ref BAKER Tech – Surge Test ).
2.3.6.Perform Interlaminar insulation test with growler test. 2.3.7.Polarity and ball rotation test. Doc. SOP TESTING Low-Med Voltage AC Motor By. Mirza Aminudin
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Electro Mechanical Workshop
2.3.8.Complete reporting of electrical condition
3. Polarization Index (P-I) test. 3.1. P-I test should be performed at the same voltage as the test in paragraph 2.1 for 10 minutes. The recommended minimum value of polarization index for winding rated class B and higer is 2.0.
PI=10 Minute Result1 Minute Result= ≥2.0 ( ref : IEEE std. 43 sec 9.2 ) 3.2. P-I test below 2.0 is acceptable if insulation resistance result is more than 5000 Megohm ( ref : IEEE Std. 43.2000. 12.2.2.2 ) 4. Surge Test – Winding analyzer. Reference to paragraph 2.3.5. from the wave graphic we can determine is winding are in good condition. Perform full reporting with print out or photograph of the result. 5. Perform No-Load Test. 5.1. Speed No-load running test should be made at rated voltage and frequency. Measure and compare with nameplate speed. 5.2. Current No-Load current should be compared with full load current. 5.3. Cooling system The cooling system must be verified as being operational 5.4. Sound level Test may be made for sound level as an indication of fault or as an irritation to those in the machine ambient. ( ref. NEMA stds. MG 1-12.53, 1-12.81, and 1-20.50 )
Doc. SOP TESTING Low-Med Voltage AC Motor By. Mirza Aminudin
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PT. BINTANG LESTARI PERSADA
Electro Mechanical Workshop
5.5. Bearing temperature Ambient and bearing housing temperatures may be measured periodically until temperatures are stabilized. 5.6. Frame temperature Ambient and Frame temperatures may be measured periodically until temperatures are stabilized. 5.7. Vibration test The vibration test should be in accordance with NEMA std. MG 1-7 for standard machine, as arrange with customer, or as necessary to check the operating characteristics of the machine. When there are special requirements, NEMA std. MG 1-7 for special machine is recommended. The unfiltered vibrations limits for resiliently mounted on standard machine (having no special vibration requirement), and based on rotational speed, are shown in next table. Vibration levels for speed above 1200 rpm are based on peak velocity of 0.15 inch/s (3.8 mm/s). Vibration limit for speed below about 1200 rpm, are based on the peak-to-peak velocity equivalent of 0.0025 inch (0.0635 mm) peak-to-peak displacement. For machine with rigid mounting, multiply the limiting value by 0.8. To obtain approximate metric rms equivalent, multiply the peak vibration in in/s by 18. Doc. SOP TESTING Low-Med Voltage AC Motor By. Mirza Aminudin
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PT. BINTANG LESTARI PERSADA
Electro Mechanical Workshop
( ref. NEMA std. MG 1-7.08.). 5.7.1.If the test pass, continue to next step 5.7.2.If the test fail, proceed to check from paragraph 2.3 then continue to paragraph 7 5.8. Performance test Full load test may be made as arrange with the customer or as necessary to check the operating characteristic of the machine. ( ref. IEEE std. 112 and 115 and NEMA std. MG-1 ) 6. Complete of testing 6.1. Providing electrical and mechanical report to customer To check and analyze result of testing or repair with customer, each report must be have detailed item name plate, workshop ref number, and specific test or repair have been perform. To give evidence that the specific repair are perform, must give photograph report. 6.2. Providing warranty letter to customer 6.3. Packaging as appropriate handing of electro motor 7. Mechanical check After dismantling motor unit that not pass electrical or testing we should verified the problems, with mechanical check we will find source of each failed criteria. 7.1. Shaft Shaft should be check for wear, cracks, scoring and straightness. 7.1.1.Shaft Extension Shaft extension should be smooth, polished and concentric with the shaft diameter. Shaft extension diameter should be checked. 7.1.2.Diameter tolerance 7.1.2.1.NEMA Frame machine
7.1.2.2.IEC frame machine
7.1.3.Permissible Run-Out 7.1.3.1.NEMA Frame machine
Doc. SOP TESTING Low-Med Voltage AC Motor By. Mirza Aminudin
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Electro Mechanical Workshop
7.1.3.2.IEC frame machine
7.1.4.Keyway width tolerance 7.1.4.1.NEMA Keyway
7.1.4.2.IEC Keyway
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Electro Mechanical Workshop
7.2. Bearing 7.2.1.Ball or Roller Bearing Check when operated for temperature, noise and vibration condition. See reference to each bearing manufacture standard for acceptance clearance. 7.2.2.Sleeve Bearing Sleeve bearing should be uniform in diameter or proper fit in the housing, smooth internally, and suitably grooved for adequate distribution of lubricant. When sleeve bearing are remanufactured or replaced by new bearings, the diametral clearance should be set to original equipment manufacturers specification if available. Otherwise, the value in table below are provided as guide.
7.2.3.Sleeve bearing end thrust Bearing of horizontal machine should be positioned on the shaft to eliminate end thrust against either bearing. 7.2.4.Oil Ring Oil ring should be true and rotate freely. Retainer, when provided, should be inspected or replaced if necessary. 7.2.5.Seals
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PT. BINTANG LESTARI PERSADA
Electro Mechanical Workshop
Seal clearance should be set to original equipment manufacturers specification if available. otherwise the value in table below provided as a guide, measure the final seal dimension.
7.3. Lubrication 7.3.1.Grease Grease passage and pipe should be clean, grease inlet should be equipped with fittings. Grease should be compatible with customer lubricant. In the absence of the machine manufacturers lubrication instruction, the grease reservoir should be filled with approximately 1/3 capacity 7.3.2.Oil Oil should be compatible with customer’s lubricant, there should be a means to determine oil level, such as oil sight gauge. 7.4. Frame and housing bearing Frame and housing bearing should be examine for defects. Cracks and breaks should be repaired and fits restored to manufacturers specification. Mounting surface tolerance, eccentricity and face run-out
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PT. BINTANG LESTARI PERSADA
Electro Mechanical Workshop
7.5. Lamination The rotor lamination should not be loose on the shaft, sleeve or spider on which the lamination stack is assembled. The fit should be restored if it is found to be loose. The outer diameter of the rotor laminations should be true and concentric with bearing journals. The stator lamination should not be loose in frame. The bore of stator laminations should be true and concentric with the rabbet (spigot) diameter of the frame. 7.6. Unbalance Dynamic balancing should be to the level specified by customer. In absence of requested level, dynamic balancing to balance quality grade G 2.5 (ISO 1940/1) should enable the machine to meet final vibration limits. Locate balance weights so they do not interfere with other components. 7.7. Rotor center Doc. SOP TESTING Low-Med Voltage AC Motor By. Mirza Aminudin
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PT. BINTANG LESTARI PERSADA
Electro Mechanical Workshop
Assemble both of housing bearing into frame and measure bearing to bearing length, compare result with rotor bearing to bearing.
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