- Record initial and corrected values on Motor Testing Record sheet. Record the lowest reading. Insulation resistance varies very little with rating. Three-phase motors: measure the resistance line-to-line for all three combinations. 2. H��W�n7�߯�yȺ� �d�Er�M. 137 0 obj <>/Filter/FlateDecode/ID[<9D9EBC62EF019E42A82C33BDF3C2C770><9D9EBC62EF019E42A82C33BDF3C2C770>]/Index[113 70]/Info 112 0 R/Length 120/Prev 540273/Root 114 0 R/Size 183/Type/XRef/W[1 3 1]>>stream scale. %PDF-1.6 %���� For rated voltage below 1KV, measured with a 500VDC Megger. Usually, if it’s open, it is infinite or well above 2K ohms. 4 Internal connection of the motors If the motor winding resistance needs to be measured the diagrams below show the internal connections for the motors used on Copeland™ semi-hermetic compressors. h��VYo�6�+|LPH��CE`���hv�q�5��ȌW]Y2d�X���P��h��E03�pF3��#ͥ%�p��@�$'�� QZ���h2"ƢT�*�`c �J�NK������O1"$:����� B�=�d��~��[�@#9���˜��� �ۮ�uV8?�\��)u�K�*K�. The Winding Arrangement section also displays the following values (in electrical degrees): Transient FEA Input Data This information is used when calculating the motor performance using the 2D time transient finite ele-ment field solver. connect to measure the resistance of each winding lead to ground. Curve A shows test values as measured; Curve B shows same values corrected to 20°C (see page 22), giving a definite downward 1. On 2-wire motors: measure the resistance from line-to-line. With the help of Ohm meter, detach the power supply from the motor. Here I assume a two pole distribution because it makes the explanation eas-ier. The test current should not exceed 10% of the nominal winding current. application/pdf 2-wire vs 4-wire measurement You can detect burned motors winding by unique smell (smells like burned lacquer). Resistance between two winding and winding - frame should be more than 1,5 Mohm. See table below. At C, the insulation resistance value after the motor has been rewound. If you open the single phase motor , you will find out that your motor have two types of winding in which one is made from thick wire gauge and one thin. Something on the order of 0.01 ohms or so. Figure 4–Typical record of insulation resistance of a mill motor. Winding Resistance. Acrobat Distiller 5.0.5 (Windows) Motor voltage also plays a part. A 24 volt motor will be low, 4160 will be quite high. If someone works with AC 3-phase motors, then it is important to know how to connect these motors in Star and Delta connection, and how to detect an electrical problem. At B, the sharp drop indicates an insulation failure. 4.1 Present motor versions (C, E &A) Single-phase: motor code C Star-Delta (Y/Δ): motor code E Part Winding 2/3:1/3: motor code A For rated voltage above 1KV, measured with a 1000VDC Megger. reference data such as a guide to Insulation Resistance Readings. Resistances of three winding should be same (+/- 5%). 4 3 2 1 TO GROUND DISCHARGE THE MOTOR WINDINGS T1 T2 T3 INCREASE METER SETTING BY 500 V; RECORD READING ON GRAPH AFTER 60 SECONDS LOWEST READING ON WINDING WITH Motors of all hp, voltage, and phase rating have similar values of insulation resistance. The winding resistance measured at the motor should fall within the values in Tables 13, 22, 24, 25, & 27. endstream endobj 19 0 obj <> endobj 24 0 obj <> endobj 1 0 obj <> endobj 4 0 obj <> endobj 7 0 obj <> endobj 10 0 obj <> endobj 13 0 obj <> endobj 16 0 obj <> endobj 18 0 obj <>stream Place meter on ohms: T1 to T2 T2 to T3 T1 to T3 The scope generally expected is.3 to 2.0 ohms, although most are all about .8ohms. Winding resistance of three-phase AC motors is measured between their terminals (all three combinations). require additional external excitation. Winding resistance measurement – How Decide if single or 2-ch measurement/current injection is appropriate Connect current and voltage measurement cables to the actual transformer winding(-s) Select test current Start test Wait for measurement results to stabilize When stable value, stop measurement/store result, discharging starts automatically where R is resistance in Ohms, V is voltage applied in Volts and I is the resulting current in Amperes. A motor with high resistance will not run - or not run with speed control (as is the case when a 3-phase motor winding opens while running). Place the meter lead on the winding that has the lowest reading. endstream endobj startxref Here’s a real world example. X\�X|'�| $���ص�$��$ ��*�� �*�{iE�|���T!�30�{ Cold electrostatic fluid bed, hot venturi spray, or hot fluid be dip for fractional horsepower motor stators and armatures: 1.7 >340°C (644°F) 160 (18.1) 8-12 s: 1300 (V/ml2) Green: B: 5388: Electrostatic fluid bed process, superior cut-through resistance and well heat, chemical and moisture resistance: 1.57 >340°C (644°F) 35 (11.3) 100: 25-35 s: 1100 (V/mil) Blue: B winding check with ohmmeter1.pdf - Free download as PDF File (.pdf), Text File (.txt) or read online for free. 113 0 obj <> endobj Motor resistance Ra (ohms) Motor inductance La (Henries) Motor inertia Jm (lb-in-sec^2) Load inertia reflected to the motor armature shaft Jload (lb-in-sec^2) Total inertia=Jm+Jload Jtotal(lb-in-sec^2) Note that the above values are stated for a single winding with dc motors, and are the phase values for a BLDC motor. Minimum insulation resistance of the winding to ground is measured with 500 V DC. 3 shows a typical scale, which reads increasing resistance values from left up to infinity, or a resistance too high to be measured. h�b```f``��������A���2,@�1��������]���^,��mXe�k�9�L]�p����m�zM־�}hrA�>t��b BL � �L J� �� �x�Gr�(30�dd�j�u@��� ,9Lz���* R6p,hq_#)T������J���G΂����*��8��A�Lr@ڔ����gd0 �\C� Measure resistance for each winding, resistance between two different winding and resistance between winding and motors frame. When measured through the drop cable, the resistance of the drop cable must be subtracted from the ohmmeter readings to get the winding resistance of the motor. - Winding DC Resistance Test - Follow USACE procedure - Three sets of results total (A to B phase, B to C phase, C to A phase) - Correct values to 40°C using the formula in step 8. 3. h�bbd```b``.�% ���d]"����0��f� f���"�`v?�9"��@� Take each resistance reading after 60 sec. %%EOF Capacitor Start Motor. 2008-10-20T14:19:06-04:00 Place meter on ohms and generally the range can be expected from 3 to 2 ohms. a Rated line-to-line voltage for three-phase ac machines, line-to-ground voltage for single-phase machines, and rated direct voltage for dc machines or field windings.. b kV is the rated machine terminal to terminal voltage.. Reference: ANSI/NETA MTS-2015 Table 100.11 - Insulation Resistance Test Values Rotating Machinery for One Minute at 40° C. Values based on IEEE Std 43-2013. uuid:f91e1a75-4ab9-4e78-aea7-f694061f3e38 (Four and six pole motors run at 1720 to endstream endobj 114 0 obj <> endobj 115 0 obj <> endobj 116 0 obj <>stream Check the motor frame (earth) from phase to phase (U to E, V to E, W to E). A three phase 460 volt 400 HP motor usually has a winding resistance so low that it takes a special four-wire micro-ohm meter to accurately measure it. (See 4 and 6 pole distri-butions on the handout from class.) Example of the variation of insulation resistance over a period of years: At A, the effect of aging and dust accumulation is shown by decreasing values. If you read zero, a brief between phases exists. Winding check....for motor connections ( Four and six pole motors run at 1720 to Minimum insulation resistance is 1 meg (... Given by the changes in stator windings temperature failed opened values greater this... 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