GB 14711-1993 General safety requirements for small and medium-sized rotating electrical machines
Some standard content:
National Standard of the People's Republic of China
Safety of small and medium size rotating electrical machineswwW.bzxz.Net
General requirements
General requirements for safety of small and medium size rotating electrical machines1 Subject content and scope of application
This standard Specifies general safety requirements for the design, manufacture and use of small and medium-sized rotating electrical machines. This standard applies to general-purpose small and medium-sized rotating electrical machines that require safety certification. This standard can also be used for general safety requirements for other special-purpose motors. This standard does not apply to traction motors and control motors. The special safety requirements for various types of motors should be established in separate standards. 2 Reference standards
5 Basic technical requirements for rotating motors
GB755
Eye screws
GB825
GB1169 Universal rubber sheathed flexible cable
GB1971
GB1981
Motor wire end mark and direction of rotation
Test method for solvent insulating paint
GB2423.4
GB2951.19
GB4207
GB 14711—93
Basic Environmental Testing Procedures for Electrical and Electronic Products Test Db: Alternating Damp Heat Test Method Wire and Cable Combustion Test Method
Compared leakage of solid insulating materials under humid conditions Determination method of tracking index and tracking index of resistance to leakage GB4942.1
GB5169.4
GB5169.6
GB5169.7
Motor housing protection classification|| tt||Fire hazard test for electrical and electronic products
Glow wire test methods and guidelines
Bad contact test method using heater
Fire hazard test for electrical and electronic products
Fire hazard test for electrical and electronic products
Bunsen burner flame test method
GB8170 Numerical rounding rules
GB12113 Measurement of contact current and ground wire current GB/T14048.1 Low-voltage switchgear and control equipment general principles JB/Z293 AC high voltage motor stator winding inter-turn insulation test specification JB/Z293
JB/Z294. AC low-voltage motor scattered embedded winding inter-turn insulation test method JB/Z346 AC low-voltage motor scattered embedded winding inter-turn insulation test Limit value JB/T5810 Motor pole coil and field winding inter-turn insulation test specification JB/T5811 AC low-voltage motor formed winding inter-turn insulation test method and limit value ZB/TK23002 DC motor armature winding inter-turn insulation test specification National Technical Supervision Bureau 1993- 11-20 Approved 1994-06-01 Implementation
3 Terms
3.1 Contact Current
GB14711-93
Figure 1 representing the current flowing into the human body impedance network in GB12113 . 3.2 Polarization index (PI)
When measuring insulation resistance, the ratio of the measured value when the test voltage is applied for 10 minutes to the measured value when the test voltage is applied for 1 minute (R1omin/Rimin). 3.3 Absorption ratio
When measuring insulation resistance, the ratio of the measured value when the test voltage is applied for 60s to the measured value when the test voltage is applied for 15s (R60s/R15). 3.4 Bad contact method
A test method for assessing the fire risk of electrical and electronic products. A special heater is used to simulate fault conditions that cause abnormal heating of a joint or terminal due to vibration, insufficient contact pressure, installation that does not meet specifications, and overcurrent, in order to evaluate its impact on the fire hazard of the insulating material holding the joint or terminal. 3.5 Glow wire method
A test method for assessing the fire risk of electrical and electronic products. The electric heating wire in the glowing state is used to simulate the heat source or ignition source of the glowing component in the faulty product, so as to evaluate the impact on the fire hazard of the insulating materials in contact with or adjacent to it in a short period of time. 3.6 Bunsen burner flame method
A test method for assessing the fire risk of electrical and electronic products. The Bunsen burner flame burning gas with a specified calorific value is used to simulate early fire conditions in the surrounding environment to evaluate the impact on the fire hazard of product shells, insulated cables, and parts. 4 Marks
4.1 Each motor should be equipped with a nameplate and rotation direction mark in accordance with the requirements of Chapter 10 of GB755. 4.2 When the allowable temperature rise of the motor insulation is higher than the assessment temperature rise, both the insulation level and the assessment temperature rise should be marked on the nameplate. 4.3 If the motor has a terminal block dedicated to the neutral line of the power supply, it should be marked with the letter symbol "N". 4.4 The protective grounding graphic symbol "" should be marked near the motor protective grounding terminal, and the letter symbol "PE" should be used when necessary. These signs should be securely fixed.
4.5 The color of the protective grounding cord must be green and yellow. This color code is prohibited for non-grounding cords. 4.6 The motor line end mark, direction of rotation, and the relationship between the direction of rotation and the line end mark should comply with the regulations of GB1971. 4.7 The motor should be equipped with a wiring mark diagram, and its wire end marks should be consistent with the motor's wiring terminal marks. The wiring diagram made of conductive material in the motor junction box must be reliably fixed to prevent accidents caused by falling off. 4.8 All marks on the motor can be made by printing, engraving, pressing or other effective marking methods. The marking materials and marking methods should ensure that the marks are clear and durable, and should not be indelible or fall off during the entire service life of the motor. 4.9 Whether the mark meets the requirements should be determined through observation and testing as follows. First, wipe the mark with a wet cotton cloth soaked in water for 15 seconds, then wipe it with a cotton cloth soaked in gasoline for 15 seconds, and wipe it back and forth once every second. After passing the above-mentioned tests and all the tests specified in this standard, the motor's markings should still remain clear and legible, cannot be easily removed, and should have no curling that is easy to move or can cause falling off. 5 Protection
5.1 The motor should have good shell protection. When determining the protection and adaptability of motor shells in different places of use, mechanical strength, impact resistance, moisture resistance, flame retardancy, corrosion resistance, thermal deformation resistance and power supply fire prevention capabilities need to be considered. 5.2 The protection level of the motor shell should be in accordance with GB4942.1 and should be clearly specified in each product standard. 5.3 Users should correctly select the protection level of the motor shell based on the motor installation location, operator level, whether it is maintained by the operator, etc. GB14711-93
5.4 If it is necessary to make holes on the motor during use, the size, number and location of the holes should consider the following factors a.
Use environment;
b.| |tt||Exposure level:
Protection against involuntary contact with live parts (including magnet wires); c.
d. Protection against the escape of molten metal, combustible insulators, particles of combustible materials or other similar combustible materials during use. 5.5 For the exposed surfaces and rotating parts of the motor, protective measures should be installed when necessary to prevent contact and burns. 5.6 The approval conditions for enclosure protection test shall be in accordance with the provisions of Chapters 5 to 7 of GB4942.1. 6 Heating
6.1 The motor should operate according to the environmental conditions specified in GB755 and product standards. The temperature rise of motor windings, cores, commutators and collector rings and the temperature limits, measurement methods and correction values ??of bearings are in accordance with Chapter 5 of GB755. 6.2 The maximum temperature inside the motor junction box and its leading flexible cables (wires) should not exceed the requirements in Table 1. Table 1 The maximum temperature allowed in the junction box
: The heat resistance grade of the motor insulation structure
The maximum temperature allowed in the junction box and on the lead soft cord
(wire)
c
Fully enclosed non-ventilated enclosure
Other enclosures
6.3 The heat test in Article 6.2 shall be conducted as follows. 6.3.1 The room temperature during the heat test should be 0~40℃. E
75
75
B
90
75
F
110
90| |tt||H
110
110
6.3.2 The external power supply wire should be a copper core insulated flexible cable (wire), and its cross-sectional area should be in accordance with Article 14.2 and the appendix of GB1169 Asked to make a selection.
6.3.3 The length of the cable (wire) led out from the junction box should not be shorter than 1.2m. 6.3.4 Power cables (wires) should be placed in cable tubes. 6.3.5 All unused openings on the junction box should be closed. 7 Contact current
7.1 The motor should have good insulation properties. When the motor is operating normally, its contact current should not exceed the specified value. For AC motors of 660V and below and frame size 160 and below, the hot contact current should not be greater than 5mA. The contact current limits and measurement methods of other motors should be specified in the product standards if necessary. 7.2 Contact current measurement wiring
Single-phase and three-phase motor measurement wiring diagrams are shown in Figure 1 and Figure 2. M in the measurement wiring diagram adopts the measurement network in Figure 1c in GB12113.
7.3 Contact current measurement method
7.3.1 The contact current should be measured after the temperature rise test. The test voltage is 105% of the maximum rated voltage of the motor, and the test frequency is the motor operating frequency.
7.3.2 The contact current should be measured between the metal parts on the motor that are easily accessible at the same time, and between the metal parts that are easily accessible on the motor and the ground.
a.
For single-phase motors, both ends of the motor winding should be switched to different polarities of the power supply in sequence (using switch P), and the protective grounding (using switch E) and When the neutral line is disconnected (use switch N), measure the maximum value of the contact current; b. For a three-phase motor, any one of the phases should be disconnected in turn (use switch L), and the protective grounding (use switch L) should be disconnected. In the case of E), measure the maximum value of the contact current.
?
N (neutral disconnection point)
?
GB 14711-93
P (polarity)
E( Ground wire disconnection point)
Figure 1
L (phase wire disconnection point)
E (ground wire disconnection point)
Figure 2||tt| |PE
PE
The motor should be insulated from the ground during measurement. The measuring electrode is a test rod. Each time the terminal A electrode is connected, the terminal B electrode should be connected to the ground first, and then connected to every other accessible component (or ground) for measurement. 8: Insulation resistance
The motor should have sufficient insulation resistance value at room temperature, hot state and after being damp. 8.1 The insulation resistance of the motor winding in the hot state or after the temperature rise test should not be lower than the provisions of Article 6.1 of GB755. 8.2 After the motor winding undergoes the damp heat test specified in Chapter 10, its thermal insulation resistance shall not be lower than that specified in Article 8.1. 8.3 Before the motor is subjected to the power frequency withstand voltage test, its room temperature insulation resistance should not be lower than that specified in GB755 6.2.1. 8.4 The dryness and cleanliness of the motor insulation can be judged by measuring the polarization index (PI) or absorption ratio. For a dry and clean motor, its polarization index (PI) is not less than 2.0 or the absorption ratio is not less than 1.3. 8.5 Insulation resistance measurement method
8.5.1 The measurement voltage of insulation resistance should be selected according to Table 2. Motor winding rated voltage
Insulation resistance measurement voltage
GB1471193
Table 2
<500
500
500~3300||tt ||1000
>3300
≥2500
For motors with embedded thermometers, the measuring voltage should not be greater than 250V when measuring the insulation resistance of the thermometer to the windings and chassis. . V | Shell, press the measurement button or turn the megohmmeter smoothly and evenly to the rated speed, and measure the insulation resistance according to the provisions of Article 8.5.3.
8.5.3 The insulation resistance Rimin of the motor winding should be measured when the test voltage is applied for 1 minute. If necessary, the insulation resistance R10min or R15s should be measured for 10min or 15s according to the requirements of Article 8.4. 8.5.4 For motor windings that need to be directly connected to the casing or connected through a protective capacitor during operation, these windings must be disconnected from the casing or protective capacitor during measurement.
8.5.5 The insulation resistance of the stator winding and rotor winding should be measured separately for pairs of wound rotor motors. 8.5.6 For motors with multiple sets of windings, the insulation resistance of each set of windings (except windings without ground insulation) should be measured separately. 8.5.7 After the insulation resistance measurement, the winding should be fully discharged to the ground. 9 Dielectric strength
The motor insulation should have sufficient dielectric strength and should be able to withstand the withstand voltage tests specified in Articles 9.1 and 9.2 without breakdown or flashover.
Safety protection measures must be taken during this test to prevent touching the test circuit and the motor under test. 9.1 Power frequency withstand voltage test
9.1.1 Before the motor winding is subjected to the power frequency withstand voltage test, the insulation resistance should be measured according to the requirements of Articles 8.3 and 8.5. 9.1.2 The test shall be carried out on the assembled motor. The state of the motor and wiring requirements during the test are in accordance with Article 6.2.1 of GB755. If the neutral point of the three-phase winding is difficult to separate, the test voltage should be applied to all outlet terminals of the three-phase winding at the same time. 9.1.3 For motors with solid components that are not designed to prevent electric shock or are easily damaged during the withstand voltage test, a withstand voltage test should be conducted before electrical connection.
9.1.4 During the test, surge capacitors, lightning arresters, current transformers, etc. connected to the motor line terminals should first be disconnected from the line terminals and connected to the core. 9.1.5 The capacitor of a capacitor motor should remain connected to the winding in the normal manner when the motor is running or starting. 9.1.6 When conducting voltage withstand tests on the field windings of brushless exciters and synchronous motors, the electronic components (diodes, thyristors) in the circuit should first be short-circuited themselves and not grounded.
9.1.7 The space heater and temperature measuring device in the test motor should be connected to the iron core. 9.1.8 The test transformer should have sufficient capacity. The capacity of the test transformer should be selected according to the following requirements: a. For motors with rated voltage 1140V and below, the capacity of the test transformer should not be less than 1kV·A for every 1kV test voltage: b.
For motors with rated voltage above 1140V For motors, for every 5kV test voltage, the capacity (S) of the test transformer should not be less than 1kV·A or based on the capacitance (C) of the motor under test, calculated according to formula (1): ST=2 yuan fCUUTNX10-
In the formula, Sr——test transformer capacity, kV·A; f——power frequency, Hz;
C——capacitance of the motor under test, F;
U——test voltage V;|| tt||(1)
GB14711—93
UTN—the rated voltage of the high-voltage side of the test transformer, V. 9.1.9 The test voltage should be measured on the high-voltage side of the test transformer with an electrostatic voltmeter or voltage transformer or with a special measuring winding of the test transformer. The voltage on the low-voltage side of the transformer should not be converted through a transformation ratio. For motors with a rated voltage of 3kV and above, a discharge ball gap can be connected in parallel between the high-voltage terminal of the test transformer and the ground. The ball gap and ball diameter are selected according to the requirements of the high-voltage electrical equipment insulation test voltage and test method. The ball gap discharge voltage should be Adjust to 1.10~1.15 times the test voltage. 9.1.10 When the test sample breaks down, the test equipment should have sound and light indication and manual reset measures. 9.1.11 The test voltage and test time of various types of motors should be in accordance with Article 6.2.2 of GB755 and relevant product standards. After the test, the windings of the motor under test should be grounded for discharge.
9.1.12 The power frequency withstand voltage test has a damage accumulation effect on the motor insulation. Repeated tests and rewinding of the motor test values ??should be reduced to the values ??specified in Article 6.2.3 of GB755.
9.1.13 The test current of the motor under test should be measured and judged on the high-voltage side of the test transformer. The scattered windings of motors with rated voltages of 1140V and below should be judged according to the following requirements;
a For a 1-min test, when the test current on the high-voltage side of the test transformer is greater than or equal to 0.5A and lasts 2s, the motor is judged to have breakdown. ;
b. For the 1s test, when the test current on the high-voltage side of the test transformer is greater than or equal to 0.5A, the motor is judged to have broken down. 9.1.14 For motor windings with rated voltages of 6000V and above, when the DC withstand voltage test is used instead of the power frequency withstand voltage test, the DC test voltage shall not exceed the power frequency withstand voltage test voltage (effective value) specified in Article 9.1.11 1.7 times. 9.2 Impulse withstand voltage test
9.2.1 The inter-turn insulation of the motor winding should be subjected to an impulse withstand voltage test. 9.2.1.1 The impulse withstand voltage test method for inter-turn insulation of motors with a rated voltage of 1140V and below shall be in accordance with JB/Z294 or JB/T5811; the impulse test voltage peak value of inter-turn insulation of scattered windings shall be in accordance with JB/ Z346 stipulates that the peak impulse test voltage of the formed winding inter-turn insulation should be in accordance with JB/T5811. 9.2.1.2 The inter-turn insulation of the formed winding of a motor with a rated voltage of 3 to 10.5 kV shall be subjected to an impulse withstand voltage test in accordance with JB/Z293. 9.2.1.3 The inter-turn insulation of DC motor armature windings with rated voltages of 110V and above shall be subjected to impulse withstand voltage tests in accordance with ZB/TK23002.
9.2.1.4 The inter-turn insulation of motor pole coils and field windings shall be subjected to impulse withstand voltage tests in accordance with JB/T5810. 9.2.2. The main insulation of the casing (ground) of motor windings, wiring boards and other insulating parts should be subjected to impulse withstand voltage tests. 9.2.2.1 For the main insulation of the formed winding of motors with a rated voltage of 3kV and above, randomly select 2 coils and embed them in the slots or wrap the slots with well-grounded conductive tape or metal foil, and apply 9.2.2.4 between the coil leads and the ground. The impulse test voltage specified in Article 9.2.2.6 shall be applied 5 times, and the interval between each time shall not be less than 1 s. 9.2.2.2 For the ground insulation of scattered or formed windings of motors with rated voltages of 1140V and below, the impulse test voltage should be applied between the winding lead terminals and the chassis in accordance with the provisions of 9.2.2.4~9.2.2.6. 9.2.2.3 For the motor wiring device, the impulse test voltage should be applied between the terminals and between the terminals and the chassis in accordance with the provisions of 9.2.2.4 to 9.2.2.6.
9.2.2.4 The test voltage waveform should be a standard lightning impulse voltage waveform, with a wavefront time of 1.2us (tolerance ±30%) and a half-peak time of 50μs (tolerance ±20%).
9.2.2.5 The positive and negative polarities of the impact test voltage are applied three times each, and the interval between each time should be no less than 1s. 9.2.2.6 The peak value of the impulse test voltage should be calculated according to formula (2), and rounded to the nearest thousand digits according to GB8170. Us=40+5000
Where: Us—motor-to-ground insulation impact test voltage (peak value), V: U motor rated voltage (effective value), V.
(2.
10 Damp heat test
GB14711-93
10.1 The motor should be able to withstand the humid conditions that may occur during normal use. 10.2 Whether the motor meets the requirements, except Unless otherwise specified, the 6-cycle test shall be carried out according to the 40°C alternating damp heat test method specified in GB2423.4. After the test, the thermal insulation resistance of the motor shall not be lower than that specified in Article 8.2, and shall pass the power frequency withstand specified in Article 9.1. For voltage test, the test voltage value should be 85% of the value specified in Article 9.1.11. 11 Durability
11.1 During normal use, the motor should not cause electrical or mechanical failures that are harmful to safety, and the insulation should not be damaged. The connecting parts should not be loose, and the elastic parts and housing parts should not age and fail. 11.2 The non-metallic materials in the motor and the motor housing parts made of it should be able to withstand weather aging for 5 years or the working period specified in the product standard. No cracking, brittleness or peeling will occur. Whether it meets the requirements shall be evaluated by functional testing according to relevant standards. 11.3 Elastic parts (such as gaskets, sealing rings, etc.) made of rubber or similar materials in the motor should be able to withstand aging. Whether it meets the requirements should be tested and evaluated according to the following method: 11.3.1 Place the elastic component in a heating chamber at 70 ± 2°C for 240 hours. The indoor atmospheric pressure and composition are the same as the surrounding air, and there is natural circulation ventilation; ||tt| |11.3.2 Place the test sample in an environment with room temperature and relative humidity of 45% to 55% for no less than 24 hours; 11.3.3 After the test, the visual test sample should have no surface cracks, shrinkage, sticky or oily phenomena. 11.4. The motor insulation structure should be resistant to electrical and thermal aging. 11.4.1 At the temperature specified by the motor insulation grade, the heat aging resistance life of the motor insulation structure should be no less than 20000h. 11.4.2 The heat aging resistance life of the motor insulation structure should be as normal. Or rapid thermal aging test standard evaluation. 12 Structure
12.1 The motor should have a wiring device that electrically connects the motor to the power supply or load, which can be in the form of fixedly installed conductive connecting bolt (wiring) terminals or chip terminals. and scattered lead wires. 12.2 The motor junction box can be an independent enclosure installed outside the motor, or it can be partially or entirely a part of the motor enclosure. The junction box should have a removable cover or cover for inspection and wiring. The cover or cover cannot be provided with measures for wires to enter and exit. The fixation of the junction box and the chassis should be separated from the fixation of the junction box cover and the junction box. The protection level of the small motor junction box should not be lower than IP44. 12.3 For rated voltage 660V For motors with auxiliary wiring and above, an additional auxiliary junction box should be installed and separated from the motor junction box, exclusively for the secondary wiring of the voltage transformer and current transformer in the junction box, or for normal operation. The lead ends of components with a voltage not greater than 50V are allowed to be wired in the junction box, but they should be separated from the motor lead ends by insulating partitions to prevent accidental contact. 12.4 The motor junction box should have appropriate available volume to accommodate the wiring device and enable it. Its electrical clearance and creepage distance shall not be less than those specified in Chapter 20 and it shall be able to withstand the impulse voltage test specified in Article 9.2.2.3. 12.5 If the motor junction box has a wire entry screw hole, it can be sealed with straight or tapered pipe threads, and the screwing length should be no less than 3.5 pitches. The number of wire entry screw holes should be specified in the product standard. The cable entry hole should be equipped with an insulating sleeve, and the cable entry hole should be sealed with rubber or similar materials before leaving the factory. 12.6 Capacitors, switches or similar devices in the motor should be firmly installed and easy to replace. Capacitors should be placed in protective covers and should not come into contact with easily accessible metal parts. If the capacitor casing is made of metal, additional insulation shall be used to separate it from accessible and ungrounded metal parts. The capacitor or its additional casing shall be able to prevent the occurrence of flying debris, sparks or material melting in the event of damage to the capacitor. The thickness of the capacitor cover made of thin steel plate should not be less than 0.5mm.
12.7 Motors with commutators should be equipped with monitoring windows that are easy to disassemble. The structure of the brush holder assembly should ensure that when the brush is worn to the point that it can no longer continue to work, the brush, spring and other parts should not electrify nearby non-energized metal parts or touch live parts, and should be able to ensure replacement. Safety when brushing or brush holding.
GB 14711-93
12.8 Terminals should be firmly connected, their structure should be able to ensure good conductivity and sufficient contact pressure, and have the expected current carrying capacity. All contact and current-carrying parts should be made of metal materials with good electrical conductivity and should have sufficient mechanical strength. If ferrous metal is used for fasteners, they should be electroplated to prevent rust according to the requirements of Chapter 23. 12.9 The insulating materials used to support and fix current-carrying components should be flame-retardant, arc-resistant, impact-resistant, power-supply fire-proof, moisture-proof and have sufficient dielectric strength and mechanical strength.
12.10 The materials of any parts on the motor casing should be able to withstand the high temperatures and mechanical stress that may occur during working conditions, and should not cause the risk of fire or electric shock due to bending, creep, or deformation. 12.11 The motor casing, outer air cover, junction box, etc. made of non-metallic materials should be resistant to moisture, oil, flame retardant and temperature changes during operation, and have sufficient durability and resistance to thermal deformation. It should not be brittle at the low temperature specified in Article 4.1.2.2 of GB755, and should be able to withstand the tests specified in Articles 11.2, 13.9, 19.2 and 21.2.4. 12.12 The bearing structure should be able to prevent bearing oil from flowing along the axis to the motor windings, current-carrying components and other equipment, causing accidents. 12.13 The motor windings should be properly tied, fixed and insulated. There should be no bare copper at the insulated ends of the windings. 12.14 The motor insulation structure should have certain moisture-proof capabilities, reliable insulation performance and mechanical properties, and should be able to withstand the tests specified in Chapters 8 to 10.
12.15 Each component of the motor insulation structure, such as magnet wires, canal insulation, binding tapes, slot wedges, impregnating paint and lead cables, etc., should be selected with different temperature resistance indexes and continuity according to the parts where they are used. The material operating at the highest conductor temperature. The main components in the insulation structure should have good compatibility and should be tested and evaluated (including insulation component substitution and insulation process substitution evaluation). 12.16 The heat-resistant temperature of the motor terminal board and the terminal box made of non-metallic materials should not be lower than the requirements in Table 1. 12.17 Except for motors that cannot leak or do not accumulate water inside, the motor should have appropriate drainage devices to prevent internal water accumulation from reducing the ground clearance and creepage distance of the windings and current-carrying components. The diameter of the drainage hole shall comply with the provisions of Article 5.2. The motor vents also serve as drainage. 12.18 When a capacitor is used for power factor compensation, the total reactive dry volt-ampere used to compensate the load end of the motor controller should not exceed the value that increases the no-load power factor of the motor to 1.
13 Mechanical Strength
13.1 The motor casing and parts should have sufficient mechanical strength and rigidity to prevent fires caused by the reduction of electrical gaps and creepage distances caused by mechanical deformation, vibration or displacement. Or accidents such as electric shock. 13.2 The assembly of the motor balance weight should be firm and reliable, and the balance weight itself should have sufficient mechanical strength to prevent harmful effects under vibration during normal operation.
13.3 The rotating parts of the motor shall be subjected to overspeed testing in accordance with Article 7.4 and Chapter 15 of GB755. After the test, there should be no permanent abnormal deformation or other defects that hinder the normal operation of the motor. The rotor winding should also meet the dielectric strength requirements of Chapter 9. 13.4 The motor should be able to withstand the short-time over-torque test specified in Article 7.2 of GB755 and Chapter 15 without sudden speed changes, stalling or harmful deformation.
13.5. The motor junction box should be solid, durable and firmly installed, without harmful deformation or looseness. Whether the motor junction box meets the requirements should be tested according to the following method. 13.5.1 When the motor is installed at any predetermined position, the junction box should be able to withstand the following vertical static pressure on its horizontal plane for 1 minute without damage. This force is exerted through a metal plane with a diameter of 50mm. a. For motors with a frame size of 100 and above, the vertical static pressure is 1060N; b. For motors with a frame size of 90 and below, the vertical static pressure should be calculated based on the pressure per unit horizontal area of ??the junction box of 139kPa, with a maximum of 1060N.
13.5.2 If the junction box is deflected or deformed after the test, the electrical clearance and creepage distance between the box and any terminal block still meet the requirements of Chapter 20 or pass the test of Article 9.2 , then the junction box is considered to be qualified. 13.6 Junction box conduit bushings that are not integrally molded with the metal enclosure, or threaded conduit openings used to install rigid metal conduit, shall have adequate mechanical strength.
Bad.
GB14711-93
Whether it meets the requirements should be tested according to the following method. Screw a short rigid metal conduit into the bushing according to the usage method, and apply the test torque in Table 3 on the pipe. The thread should not have any breakage. Table 3
Inlet Threaded Conduit Specifications
M12×1.5
M20X1.5
M24×1.5
M30×2
M36×2
M52×2
Test torque
N·m
34
57
80
113
136
181
13.7 Terminal boards and terminal blocks should have sufficient mechanical strength and rigidity and should not be damaged when withstanding the tightening torques in Table 4. Table 4
Terminal diameter
mm
Tightening torque
N·m
1.2
5
2.0
6
3.0
8
6.0
10
10.0
12
15.5|| tt||16
30.0
13.8 The outer windshield and fan of the motor should have sufficient mechanical strength and should be firmly installed without harmful deformation or looseness. 20
52.0
24
80.0
13.9 The non-metallic motor housing (including junction box and outer wind cover) should be able to withstand a weight of 0.5kg at room temperature Impact test of steel ball from any angle. The impact energy is 6.7J, and the test method is in accordance with Article 8.1.10 of GB/T14048.1. After the test, there should be no damage that affects its continued use, or no reduction in electrical clearances and creepage distances (surface cracks, dents and chips that are not harmful to protection against electric shock below the specified value can be ignored).
13.10 The thickness of the motor base and feet should be selected according to the motor frame size, protection level, structural form, material and processing technology, and should have sufficient mechanical strength, rigidity and stability. 13.11 The lifting rings or similar devices used for lifting the motor and its components should have sufficient mechanical strength and will not cause permanent deformation or rotation due to load.
The installation place of the lifting ring should be strengthened, the screw hole should have sufficient screwing length, and have a flat surface that matches the lifting ring. For motors with a single lifting point, they should be able to be lifted at any angle between 0° and 30° from the designed lifting direction; for motors with multiple lifting points, they should be able to be lifted at any angle between 0° and 45°. When there are multiple lifting rings, the force angle during lifting should be considered. The allowable static load and test methods of lifting rings are in accordance with GB825. 13.12 When lifting several lifting points at the same time, use row hooks to reduce the lifting angle and prevent damage to the motor casing. 13.13 When lifting, measures should be taken to prevent overload risks caused by acceleration, deceleration or impact. 4. When the motor is assembled on a common bottom plate, the lifting device of the bottom plate should be used for lifting. Do not use the lifting device of the motor alone to lift the unit and the 13.14
bottom plate.
13.15
When lifting or loading and unloading below 0℃, attention should be paid to the impact of low temperature on the toughness of the lifting device.
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