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Machinery Industry Standard of the People's Republic of China
JB/T 7087-1997
Electric Tool Switch
Published on September 5, 1997
Ministry of Machinery Industry of the People's Republic of China
Implemented on January 1, 1998
JB/T7087-1997
This standard is the first revision of JB7087-1993 "Electric Tool Switch". This standard puts forward specific requirements for the classification, model, technical requirements and test methods of electric tool switch products in accordance with GB1502.1--1994 "Appliance Switch Part 1: General Requirements"; at the same time, on the basis of JB708793, the model, mark, electric shock protection and breaking capacity test of electric tool switches have been revised. This standard is proposed and managed by the Appliance Switch Branch of the National Technical Committee for Standardization of Electrical Accessories. This standard was first issued in 1993.
This standard is entrusted to the National Electrical Accessories Standardization Technical Committee Appliance Switch Branch for interpretation. The drafting unit of this standard: Shanghai Electric Tool Research Institute of the Ministry of Machinery Industry. The drafters of this standard: Zhang Weichang and Liu Jiang. 1 Scope
Standards of the Machinery Industry of the People's Republic of China
Electric Tool Switches
JB/T7087-1997
Replaces JB7087-1993
This standard mainly specifies the classification of electric tool switches (hereinafter referred to as switches), basic requirements for safety and performance, and corresponding test methods and inspection rules.
This standard is applicable to electric tool switches used under general environmental conditions, with a maximum working voltage of no more than 440V AC, a frequency of no more than 400Hz, and a rated current of no more than 63A. This type of switch is installed on the electric tool body or accessories to connect and disconnect current or change the rotation direction of the electric tool, limit the no-load speed, adjust the operating speed, and other protection and control purposes. Switches used for DC electric tools can refer to this standard. Switches used in special environments or for special purposes must be supplemented with regulations in product standards. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T2828-1987
GB3883.191
GB4208—1993
GB15092.1—94
GB/T13862—92
GB/T192—1981
GB/T193—1981
GB/T19 6—1981
GB/T197-1981
JB/T6212—92
ZBK64 009—88
JB7079—93
3 Definition
Count sampling procedure and sampling table for batch inspection (applicable to inspection of continuous batches) Safety of hand-held electric tools Part 1 General requirements (idtIEC745-1) Degrees of protection of enclosures (IP code) (eqvIEC529—1989) Part 1 General requirements (idtIEC1058—1—1990) Appliance switches
Appliance switches
Ordinary thread||t t||Ordinary thread
Ordinary thread
Basic test method
Basic tooth profile
Diameter and pitch series (diameter 1~600mm) Basic size (diameter 1~600mm)
Tolerance and fit (diameter 1~355mm)
Ordinary thread
Method for compiling model of appliance switch
Internal wiring connector of power tool
Spring-driven impact tester and its calibration The following definitions apply to this standard.
3.1 Forward and reverse switch change-overswitch A switch that has the ability to connect and disconnect current, changes the connection state of the internal circuit of the power tool, and thus changes the direction of operation of the power tool. 3.2 Forward and reverse device changeoverdevice A device that does not have the ability to connect and disconnect current, and only changes the connection state of the internal circuit of the power tool when no current flows, thereby changing the direction of operation of the power tool.
3.3 Speed regulator switch switch with speed regulator A switch that adjusts and controls the speed of the power tool. 3.4 Speed limit switchbzxZ.net
swith with speed restraint
Approved by the Ministry of Machinery Industry on September 5, 1997
Implemented on January 1, 1998
JB/T 7087 -1997
A switch that can limit the no-load speed of the power tool and has little effect on the load speed. Automatic reset
biased return
When sufficient external force acts on the switch's operating member, it causes the moving contact in the switch to move. When the external force is removed, the moving contact automatically returns to its original state.
Closed locking switch
\on\locked switch
Automatic reset switchWhen the contacts are in the on position under the action of external force, the operator can lock it with the same hand through a simple operation. After the external force is removed, the contacts remain in the on position and can be unlocked through another simple operation. 3.7
\off\locked switch
Disconnected locking switch
The switch contacts are originally in the off position. The operator must first unlock them before operating the actuator to close the contacts. When the external force acting on the actuator is removed, the contacts automatically return to the off position and are automatically locked. 3.8Instantaneous action
instantaneousaction
The closing or opening speed between the moving and static contacts is determined by the mechanism itself and has nothing to do with the movement speed of the operating part. 3.9
Plug-in switch
The switch is electrically connected to the power tool. The switch is inserted into a dedicated plug through the plug on it. Basic parameters
The basic parameters of the switch are specified in Table 1.
Table 1 Basic parameters
Power type and voltage
100,150:200
250;300;400
Classification, model and mark
5.1 Classification
5.1.1 According to the nature of the power supply
Maximum working voltage
) AC power (50Hz/60Hz) switch: b) AC medium frequency (>60~400Hz) switch. 5.1.2 According to the ambient temperature:
Rated voltage priority
a) Switches used in the maximum ambient temperature not exceeding 55°C; b) Switches used in the maximum ambient temperature between 55°C and 85°C c) Switches used in the minimum ambient temperature not less than -40°C Rated voltage of resistive load and motor load A
4,6;10,16;25;32#40;63
2;4,6#10#16:25:32
1,2,4;6:10:16;25
1+2; 4:6:10,16
4:6:10:16#25#32:40,63
2#4#610#16;25;32
1; 2: 4; 6# 10# 16; 25
d》Switches used in the lowest environmental temperature range of -40℃~-20℃ including -20℃; e) Switches used in the lowest environmental humidity range of -20℃~-15℃ including -15℃, divided by the number of operating cycles:
a) 100000 times;
b) 50000 times;
c) 25000 times;
d) 10000 times.
JB/T 7087 - 1997
Note: Usually the number of operating cycles of electric tool switches is 50000 times, divided by protection level:
As part of the tool housing, the switch should be installed according to the manufacturer's regulations to prevent the harmful intrusion of solid foreign objects and water, divided into (according to the provisions of GB4208):
a) Protection greater than 1.0mm solid foreign body (IP4X), b) dustproof (IP5X);
c) dusttight (IP6X)
d) non-waterproof (IPXo);
e) drip-proof (IPX1);
f) anti-tilt 15 degrees (IPX2):
g) rainproof (IPX3);
h) splashproof (IPX4);
i) spray-proof (IPX5);
j) immersion-proof (IPX7).
5.1.5 According to function:
a) Momentary action switch;
b) Non-momentary action switch (M);
c) Non-automatic reset switch (F);
d) Automatic reset non-self-locking switch (W);
e) Automatic reset closed locking switch (B); f) Automatic reset open locking switch (D);
g) Speed regulating switch (E);
h) Speed limiting switch (S);
i) Forward and reverse switch (K);
j) Forward and reverse device (Z);
k) Vibration-resistant switch (N);
1) Switch with grounding terminal (J);
m) Switch with transition grounding terminal (G):
n) Plug-in structure switch (C).
1The letters in brackets are auxiliary codes.
Most electric tool switches are instantaneous. To simplify the model, this type of switch is not given a code. 2
5.1.6 Classification by level:
a) single pole (1);
b) two poles (2);
c) three poles (3).
Note: The numbers in brackets are auxiliary codes, see 5.2.2.5.2
Model composition
FO-O/OXXO
JB/T7087-1997
Derived code (expressed in Arabic numerals) Function code (expressed in Chinese phonetic capital letters) Number of poles (expressed in Arabic numerals)
Specification code (expressed in Arabic numerals) Design code (expressed in Arabic numerals) Feature code (expressed in Chinese phonetic capital letters) Category code
5.2.1 The category code, feature code, design code and specification code of the switch shall comply with the provisions of JB/T6212. 5.2.2 The number of poles, function code and derived code of the switch shall be expressed in accordance with the numbers in brackets in 5.1.6. The function code shall be expressed in accordance with the letters in brackets in 5.1.5. Derived codes are used for derived products and can be used to indicate the switch handle type, size, self-locking type, size, color, etc. For example: a push-button switch installed in an electric tool to control the motor has a design code of 4, a resistive load rated current of 6A, and a two-pole automatic reset closed locking switch. Its model is: FA4-6/2B. 5.3 Markings on the switch
5.3.1 Marks that should be on the switch:
a) Manufacturer's name or trademark;
b) Model:
c) Maximum working voltage (or rated voltage), rated current and power type (according to the provisions of 5.3.2); d) Power terminal symbol: The terminal for connecting the power cord must be marked with a small arrow pointing to the terminal in a conspicuous place next to the terminal. If there is no small arrow, it means that the terminal for connecting the power cord can be arbitrary or marked with a wiring diagram; e) Disconnect mark (only applicable to non-automatic reset switches), usually ○ indicates the disconnect position; f ）The terminal connected to the ground wire shall be marked with the ground symbol (), g) Operation cycle number mark (the representation method shall be in accordance with the provisions of 5.3.4), the switch with an operation cycle number of 10,000 times does not need this mark; h) Ambient temperature limit mark (the representation method shall be in accordance with the provisions of 5.3.3), if there is no temperature mark, it means that the rated ambient air temperature range is 0~55℃,
i) Protection level mark (in accordance with the representation method specified in GB4208), which can be expressed in the form of a document; i) Certification mark, when the certification license has been obtained, it can be marked on the switch according to the relevant provisions of the certification mark; k) Class 1 structural symbols should not be used on the switch. 5.3.2 The maximum working voltage (or rated voltage), rated current and power supply type can be expressed in the following way. The rated current of the motor load is enclosed in parentheses, the resistive load current is not enclosed in parentheses, and is written first, followed by the current unit A, the voltage value is placed to the right of A and then marked with the voltage unit V, and the power supply type symbol is on the right, AC is ~, and the AC switch other than 50Hz or 60Hz is marked with the frequency number and unit Hz. For example: 6 (4) A 250 V ~ 400 Hz; if the frequency is 50 Hz or 60 Hz, it can also be expressed as: 6 (4) / 250 ~ or 250
6 (4)
5.3.3 Expression of rated ambient temperature:
The letter T is used as the boundary, the left side represents the limit below zero, and the right side represents the upper limit. For example: the rated ambient temperature of the switch is between -20 ° C and 85 ° C, which can be expressed as 20T85;
5.3.4 Expression of rated number of operating cycles: E is used as the boundary, the left side of E is the numerical value, and the right side of E represents the power of 10. For example: the rated number of 4
operating cycles is 50,000 times, which can be expressed as 5E4. JB/T7087-1997
5.3.5 The mark of the switch shall be marked on the main body of the switch. It is allowed to be marked on non-detachable parts, but not on screws, washers or other parts that may be removed during switch wiring and installation. The mark of small-sized switches can be marked on different surfaces of the main parts. 5.3.6 The mark of the switch shall be clear and durable. The mark shall withstand the following wiping test. a) Use a piece of absorbent cotton soaked in distilled water to wipe 15 times back and forth in about 15 seconds: b) Then use a piece of absorbent cotton soaked in No. 200 solvent gasoline to wipe 15 times back and forth in about 15 seconds. During the test, the soaked absorbent cotton should be pressed on the mark with a pressure of about 2N/cm. The mark should still be easily recognizable after the test. 6 Technical requirements and test methods
6.1 General requirements
6.1.1 The switch should be able to work normally under the following general environmental conditions; a) not more than 2000m above sea level;
b) within the rated ambient temperature range;
c) relative humidity of air not more than 90% (25℃). 6.1.2 The switch should be manufactured according to the drawings and technical documents approved by the prescribed procedures. 6.1.3 The switch should be safe and reliable when the power tool is in normal use, and will not cause danger to people and the surrounding environment even if negligence may occur during normal use.
6.1.4 The switch should be fully assembled, with a smooth appearance, no defects, and uniform color. 6.2 Protection against electric shock
6.2.1 The switch shall have adequate protection against electric shock. When installed and used in accordance with the method specified by the manufacturer, the human body shall not touch the live parts. The parts of the switch that can be touched by the human body, such as the handle and self-locking button, shall be made of insulating materials. If they are made of metal materials, the metal parts and the live parts shall meet the requirements of reinforced insulation or double insulation, except for switches used for tools. 6.2.2 If the live parts can be touched after the actuator is removed, the switch operating parts shall be fully tightened. If the live parts can only be touched in the following cases, the operating parts are considered to be fully tightened: a) The actuator is broken or split;
b) The actuator cannot be removed by using a tool that can turn a screw or threaded part, and other tools must be used to remove the operating parts. Check by observation.
6.2.3 Paint, ordinary paper, cotton fabric, oxide film or sealant that softens when heated shall not be used as protection against accidental contact with live parts. 6.2.4 If the switch contains a capacitor, it shall not be connected to any accessible metal parts. If the casing of the capacitor is made of metal, additional insulation shall be used between the casing and the accessible metal. 6.3 Grounding terminals and transition terminals
Terminals for grounding continuity are allowed in switches, but switches used for Class II appliances shall not have devices for grounding the switch or its parts.
Terminals for transition wiring are allowed in switches. Grounding terminals, grounding terminals and other grounding devices shall not be electrically connected to the neutral terminal. The connection between grounding terminals, grounding terminals and other grounding devices and the parts connected to them shall be low resistance, and the contact resistance shall not exceed 50mQ. The measurement method shall be carried out in accordance with the provisions of 10.4 of CB15092.1. The grounding clamping device shall not be loosened without using tools, and the clamping device shall be fully locked to prevent accidental loosening. All parts of the grounding terminal shall not cause corrosion due to contact with copper or other metal of the grounding conductor. 6.4 Terminals
6.4.1 General requirements
6.4.1.1 The terminals should be fixed and should not become loose when the wires are removed or installed. 5
JB/T7087-1997
Floating terminals are allowed, but their floating shall not hinder the normal operation of the switch. The test is conducted by clamping and loosening a wire with the maximum cross-sectional area specified in Table 2 10 times each. The torque applied to the screw-type terminals shall be as specified in Table 7.
6.4.1.2 The terminals should be able to connect the wires specified in Table 2, and the wires should not slip out of the terminals. Connect the wires with the maximum cross-sectional area specified in Table 2 to the terminals, tighten the clamping device with the torque specified in Table 7, and then connect the wires with the minimum cross-sectional area specified in Table 2 to the terminals. Repeat the above test. The wires should not slip out of the terminals. Table 2 Current and wire cross-sectional area
Electrical current carried by terminals1
3<≤6
6≤10
10<≤16
16<≤25
25<≤32
32≤40
40≤63
Cross-sectional area
Panzi gauge
Cross-sectional area
Terminal gauge
6.4.1.3 The switch terminals used to connect flexible cables or cords should ensure that when part of the core wire comes out, it will not touch the live parts of different polarities or accessible metal parts, nor will it cause a short circuit between terminals that can only be electrically connected through the action of the switch. The test method is as follows:
Strip 8mm of insulation from the end of the soft wire with the minimum cross-sectional area specified in Table 2, leaving one strand of wire outside, and insert and clamp the rest into the terminal. Without causing the insulation to crack, turn the strand of wire left outside in all possible directions. If there is a grounding terminal in the switch, the strand of wire left outside must also be turned in all possible directions. 6.4.1.4 The selected terminal must comply with the relevant provisions of GB15092.1, and the terminal for connecting the power supply must be a threaded terminal.
6.4.2 Threaded terminals
6.4.2.1 Forms and dimensions of threaded terminals a) The type of screw terminals is shown in Figure 1, and the dimensions shall comply with the provisions of Table 3; b) The type of bolt terminals is shown in Figure 2, and the dimensions shall comply with the provisions of Table 3; 6
JB/T7087-1997
A-fixing component, B-washer or pressure plate; C-clamping plate, D-wire placement space: E-screw: F-wire; G-maximum spacing between parts that constrain the wire Figure 1
Screw terminal
Table 3 Parameters of screw and bolt terminals
Connectable wire carrying area
0. 75~1.5
Minimum
Nominal
D of the thread, the minimum nominal diameter of the screw thread, the maximum thread length on the screw, the maximum thread length in the screw hole, the minimum space size D of the safety conductor, the minimum nominal
diameter between the screw head and the rod, A-enclosing component; B-washer Ring or pressure plate; C- clamping plate, D—wire placement space; E--bolt, F wire; G-maximum gap between parts that constrain the wire Figure 2 Bolt terminal
Constraining wire
Between parts
Maximum gap
Screw head
JB/T7087-1997
The dimensions of washers or pressure plates used in screw and bolt terminals shall comply with the requirements of Table 4. Table 4 Dimensions of washers or pressure plates used in screw bolt terminals Thread nominal diameter
Maximum difference between thread diameter and washer inner diameter mm
Minimum difference between thread diameter and washer outer diameter mm.
c) The type of column type terminals is shown in Figure 1 of GB15092.1. The dimensions should comply with the provisions of Table 5. Table 5 Dimensions of column type terminals
Wire carrying area
Minimum thread
Nominal diameter
Wiring hole size
d) The type of lug type terminals is shown in Figure 3. The dimensions should comply with the provisions of Table 6. Length of thread in column
Minimum value
A-locking device; B-electrical terminal, C-screw or bolt; D-fixed partg-distance between hole edge and both sides of clamping;-minimum distance between hole edge and fixed part Figure 3 Lug terminal
Minimum distance between wire end and clamping screw
Circuit current1
10≤16
16≤25
32<≤40
6. 4. 2. 2
JB/T7087-1997
Minimum nominal diameter of thread
Dimensions of lug-type terminals
Maximum difference between thread diameter and lug
Aperture diameter
Minimum distance between hole edge and connection edge
Minimum distance between hole edge and fixed part
Threaded terminals should be able to reliably clamp the wire on the metal surface, which is checked by the following test. The terminals are connected to the wires with the minimum and maximum cross-sectional areas specified in Table 2, respectively, and tightened with 2/3 of the torque shown in the corresponding column of Table 7. If the screws are slotted hexagon head screws, 2/3 of the torque shown in the second column of Table 7 is applied to tighten each wire. The axial tension specified in Table 8 lasts for 1 min. The tension should not be applied suddenly, and the wire should not be obviously displaced in the terminal. Table 7 Torque for tightening screws
Nominal thread diameter
Applicable to headless screws that do not protrude from the hole after tightening; screws that cannot be tightened with other screwdrivers with a blade width larger than the screw diameter; Applicable to other screws tightened with screwdrivers; Applicable to screws not tightened with screwdrivers
Cross-sectional area of wire
Tension force N
Except for column-type terminals, other types of threaded terminals should be equipped with spring washers to prevent loosening 6.4. 2. 3
6.4.2.4 The end of the screw that clamps the wire in the column terminal should be made into a spherical or inclined plane, and there should be no flanges or sharp corners that damage the wire. After the wire damage test, the wire clamping part should not be broken or have obvious cracks. The wire damage test uses the structure shown in Figure 4 (the H value in Figure 4 is specified in Table 9), and the soft wire is clamped with the torque specified in Table 7. The wire is subjected to the tension specified in Table 8, and the wire is rotated in a balanced manner within 5s, and then rotated in the opposite direction within 5s. During the rotation process, the wire should not be subjected to torque. After the test, the wire should not have obvious cracks. 91 Forms and dimensions of threaded terminals a) The type of screw terminals is shown in Figure 1, and the dimensions shall comply with the provisions of Table 3; b) The type of bolt terminals is shown in Figure 2, and the dimensions shall comply with the provisions of Table 3; 6
JB/T7087-1997
A-fixing component, B-washer or pressure plate; C-clamping plate, D-wire placement space: E-screw: F-wire; G-maximum spacing between parts that constrain the wire Figure 1
Screw terminal
Table 3 Parameter table of screw and bolt terminals
Connectable wire carrying area
0. 75~1.5
Minimum
Nominal
D of the thread, the minimum nominal diameter of the screw thread, the maximum thread length on the screw, the maximum thread length in the screw hole, the minimum space size D of the safety conductor, the minimum nominal
diameter between the screw head and the rod, A-enclosing component; B-washer Ring or pressure plate; C- clamping plate, D—wire placement space; E--bolt, F wire; G-maximum gap between parts that constrain the wire Figure 2 Bolt terminal
Constraining wire
Between parts
Maximum gap
Screw head
JB/T7087-1997
The dimensions of washers or pressure plates used in screw and bolt terminals shall comply with the requirements of Table 4. Table 4 Dimensions of washers or pressure plates used in screw bolt terminals Thread nominal diameter
Maximum difference between thread diameter and washer inner diameter mm
Minimum difference between thread diameter and washer outer diameter mm.
c) The type of column type terminals is shown in Figure 1 of GB15092.1. The dimensions should comply with the provisions of Table 5. Table 5 Dimensions of column type terminals
Wire carrying area
Minimum thread
Nominal diameter
Wiring hole size
d) The type of lug type terminals is shown in Figure 3. The dimensions should comply with the provisions of Table 6. Length of thread in column
Minimum value
A-locking device; B-electrical terminal, C-screw or bolt; D-fixed partg-distance between hole edge and both sides of clamping;-minimum distance between hole edge and fixed part Figure 3 Lug terminal
Minimum distance between wire end and clamping screw
Circuit current1
10≤16
16≤25
32<≤40
6. 4. 2. 2
JB/T7087-1997
Minimum nominal diameter of thread
Dimensions of lug-type terminals
Maximum difference between thread diameter and lug
Aperture diameter
Minimum distance between hole edge and connection edge
Minimum distance between hole edge and fixed part
Threaded terminals should be able to reliably clamp the wire on the metal surface, which is checked by the following test. The terminals are connected to the wires with the minimum and maximum cross-sectional areas specified in Table 2, respectively, and tightened with 2/3 of the torque shown in the corresponding column of Table 7. If the screws are slotted hexagon head screws, 2/3 of the torque shown in the second column of Table 7 is applied to tighten each wire. The axial tension specified in Table 8 lasts for 1 min. The tension should not be applied suddenly, and the wire should not be obviously displaced in the terminal. Table 7 Torque for tightening screws
Nominal thread diameter
Applicable to headless screws that do not protrude from the hole after tightening; screws that cannot be tightened with other screwdrivers with a blade width larger than the screw diameter; Applicable to other screws tightened with screwdrivers; Applicable to screws not tightened with screwdrivers
Cross-sectional area of wire
Tension force N
Except for column-type terminals, other types of threaded terminals should be equipped with spring washers to prevent loosening 6.4. 2. 3
6.4.2.4 The end of the screw that clamps the wire in the column terminal should be made into a spherical or inclined plane, and there should be no flanges or sharp corners that damage the wire. After the wire damage test, the wire clamping part should not be broken or have obvious cracks. The wire damage test uses the structure shown in Figure 4 (the H value in Figure 4 is specified in Table 9), and the soft wire is clamped with the torque specified in Table 7. The wire is subjected to the tension specified in Table 8, and the wire is rotated in a balanced manner within 5s, and then rotated in the opposite direction within 5s. During the rotation process, the wire should not be subjected to torque. After the test, the wire should not have obvious cracks. 91 Forms and dimensions of threaded terminals a) The type of screw terminals is shown in Figure 1, and the dimensions shall comply with the provisions of Table 3; b) The type of bolt terminals is shown in Figure 2, and the dimensions shall comply with the provisions of Table 3; 6
JB/T7087-1997
A-fixing component, B-washer or pressure plate; C-clamping plate, D-wire placement space: E-screw: F-wire; G-maximum spacing between parts that constrain the wire Figure 1
Screw terminal
Table 3 Parameter table of screw and bolt terminals
Connectable wire carrying area
0. 75~1.5
Minimum
Nominal
D of the thread, the minimum nominal diameter of the screw thread, the maximum thread length on the screw, the maximum thread length in the screw hole, the minimum space size D of the safety conductor, the minimum nominal
diameter between the screw head and the rod, A-enclosing component; B-washer Ring or pressure plate; C- clamping plate, D—wire placement space; E--bolt, F wire; G-maximum gap between parts that constrain the wire Figure 2 Bolt terminal
Constraining wire
Between parts
Maximum gap
Screw head
JB/T7087-1997
The dimensions of washers or pressure plates used in screw and bolt terminals shall comply with the requirements of Table 4. Table 4 Dimensions of washers or pressure plates used in screw bolt terminals Thread nominal diameter
Maximum difference between thread diameter and washer inner diameter mm
Minimum difference between thread diameter and washer outer diameter mm.
c) The type of column type terminals is shown in Figure 1 of GB15092.1. The dimensions should comply with the provisions of Table 5. Table 5 Dimensions of column type terminals
Wire carrying area
Minimum thread
Nominal diameter
Wiring hole size
d) The type of lug type terminals is shown in Figure 3. The dimensions should comply with the provisions of Table 6. Length of thread in column
Minimum value
A-locking device; B-electrical terminal, C-screw or bolt; D-fixed partg-distance between hole edge and both sides of clamping;-minimum distance between hole edge and fixed part Figure 3 Lug terminal
Minimum distance between wire end and clamping screw
Circuit current1
10≤16
16≤25
32<≤40
6. 4. 2. 2
JB/T7087-1997
Minimum nominal diameter of thread
Dimensions of lug-type terminals
Maximum difference between thread diameter and lug
Aperture diameter
Minimum distance between hole edge and connection edge
Minimum distance between hole edge and fixed part
Threaded terminals should be able to reliably clamp the wire on the metal surface, which is checked by the following test. The terminals are connected to the wires with the minimum and maximum cross-sectional areas specified in Table 2, respectively, and tightened with 2/3 of the torque shown in the corresponding column of Table 7. If the screws are slotted hexagon head screws, 2/3 of the torque shown in the second column of Table 7 is applied to tighten each wire. The axial tension specified in Table 8 lasts for 1 min. The tension should not be applied suddenly, and the wire should not be obviously displaced in the terminal. Table 7 Torque for tightening screws
Nominal thread diameter
Applicable to headless screws that do not protrude from the hole after tightening; screws that cannot be tightened with other screwdrivers with a blade width larger than the screw diameter; Applicable to other screws tightened with screwdrivers; Applicable to screws not tightened with screwdrivers
Cross-sectional area of wire
Tension force N
Except for column-type terminals, other types of threaded terminals should be equipped with spring washers to prevent loosening 6.4. 2. 3
6.4.2.4 The end of the screw that clamps the wire in the column terminal should be made into a spherical or inclined plane, and there should be no flanges or sharp corners that damage the wire. After the wire damage test, the wire clamping part should not be broken or have obvious cracks. The wire damage test uses the structure shown in Figure 4 (the H value in Figure 4 is specified in Table 9), and the soft wire is clamped with the torque specified in Table 7. The wire is subjected to the tension specified in Table 8, and the wire is rotated in a balanced manner within 5s, and then rotated in the opposite direction within 5s. During the rotation process, the wire should not be subjected to torque. After the test, the wire should not have obvious cracks. 9
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