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JB/T 6526-1999 Electronic speed control switch for electric tools

Basic Information

Standard ID: JB/T 6526-1999

Standard Name: Electronic speed control switch for electric tools

Chinese Name: 电动工具用电子调速开关

Standard category:Machinery Industry Standard (JB)

state:Abolished

Date of Release1999-08-06

Date of Implementation:2000-01-01

Date of Expiration:2007-04-01

standard classification number

Standard Classification Number:Electrical Engineering>>Electrical Equipment and Apparatus>>K64 Power Tools

associated standards

alternative situation:Replaces JB/T 6526-1992; replaced by JB/T 6526-2006

Publication information

publishing house:Mechanical Industry Press

Publication date:2000-01-01

other information

Focal point unit:National Electric Tools Standardization Technical Committee

Introduction to standards:

JB/T 6526-1999 Electronic speed control switch for electric tools JB/T6526-1999 Standard download decompression password: www.bzxz.net

Some standard content:

Mechanical Industry Standard of the People's Republic of China
Electronic Speed ​​Regulating Switch for Electric Tools
JB/T 65261999
Replaces JB/T6526-92
This standard mainly specifies the classification, model, basic requirements for safety and performance of electronic speed regulating switches for electric tools and the corresponding test methods and inspection rules.
This standard is applicable to single-phase electronic speed regulating switches for electric tools (hereinafter referred to as switches) with a maximum working voltage of no more than 250V AC, a frequency of 50/60Hz, and a rated current of no more than 32A, which are used under general environmental conditions. Such switches are installed on the body or accessories of electric tools to connect and disconnect current or change the direction of rotation of electric tools, limit no-load speed, and adjust the operating speed. Switches used in special environments or switches for special purposes must be supplemented 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 the standard, the versions shown are all valid. All standards are subject to revision and parties using this standard should investigate the possibility of using the most recent versions of the following standards. GB/T192~197—1981 Ordinary Thread
GB/T2828—1987
GB3883.1—1991
GB4208—1993
GB/T13384--1992
GB/T13862—1992
GB/T15092.1—1994
JB/T6212—1992
JB/T7087—1997
JB7079—1993
JB/T9604—1999
Batch Inspection Count Sampling Procedure and Sampling Table (Applicable to Inspection of Continuous Batch) Hand-held Power Tools Safety of Part 1: General requirements (idtIEC60745-1: 1991) Degrees of protection of enclosures (IP code) (idtIEC60529: 1989) General technical conditions for packaging of electromechanical products
Basic test methods for appliance switches
Appliance switches Part 1: General requirements (idtIEC61058-1: 1990) Methods for compiling appliance switch models
Electric tool switches
Spring-driven impact tester and its correction Electric tool internal wiring connectors
Appliance switches Part 2: Particular requirements for change-over selectors IEC61058-2-5: 1994
3 Definitions
The following definitions apply to this standard.
3.1 Printed-board
A printed-circuit board dedicated to speed switches, with certain electronic components and conductive circuits. 3.2 Forward and reverse device change-over device does not have the ability to connect and disconnect current, and only changes the internal circuit connection state of the power tool when there is no current flowing, thereby changing the direction of operation of the power tool.
3.3 Speed ​​regulator switch with speed regulator adjusts the switch that controls the speed of the power tool. 3.4 Speed ​​limit switch switch with speed restraint can limit the no-load speed of the power tool, and has little effect on the load speed. Approved by the State Bureau of Machinery Industry on August 6, 1999, implemented on January 1, 2000. This standard is the first revision of JB/T6526-92 "Electronic speed control switch for electric tools". This standard is in accordance with GB15092.1-1994 "Appliance switches Part 1: General requirements" and JB/T7087-1997 "Electrical tool switches", and puts forward specific provisions on the classification, model, technical requirements and test methods of electronic speed control switches for electric tools; at the same time, it makes major revisions to JB/T6526-92 in terms of specific content. This standard is written in accordance with GB/T1.1-1993 "Guidelines for standardization work Unit 1: Basic provisions for drafting and expression rules of standards". This standard is proposed and managed by the National Technical Committee for Standardization of Electrical Accessories. This standard was drafted by: Shanghai Electric Tool Research Institute. This standard was drafted by: Zhang Weichang, Liu Jiang. This standard is entrusted to the National Technical Committee for Standardization of Electrical Accessories for interpretation. Part 1: Standard
3.5 Automatic reset biased return
JB/T6526—1999
When sufficient external force acts on the operating part of the switch, the moving contact in the switch is caused to move. When the external force is removed, the moving contact automatically returns to its original state.
3.6 Closed locked switch "on" locked switch automatic reset When the switch 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-lock switch "off" locked switch The switch contacts are originally in the off position. The operator must first unlock 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. 3.8 Instantaneous action 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 actuator. 3.9 Plug-in switch The switch is plugged into a dedicated socket through its plug-in, so that the switch and the power tool are electrically connected. 3.10 Electronic disconnection The switch uses semiconductor devices to cut off the circuit at at least one pole, but it is neither completely disconnected nor slightly disconnected. 3.11 Rated load
Rated load
The load that ensures the rated current of the switch at the highest working voltage. Basic parameters
The basic parameters of the switch are specified in Table 1.
Table 1 Basic parameters
Power supply type and rated power
Classification, model and mark
5.1 Classification
5.1.1 According to the purpose:
Maximum working voltage
a) One-way electronic speed control switch;
b) Two-way electronic speed control switch.
Rated voltage priority value
One-way electronic speed control switch refers to the switch that makes the power tool rotate in one direction,1
2Two-way electronic speed control switch refers to the switch that makes the power tool rotate in both positive and negative directions. 5.1.2 According to the speed control type:
a) Stepless electronic speed control switch;
b) Stepped electronic speed control switch.
5.1.3 According to the operation mode:
a) Manual electronic speed control switch;
b) Foot-operated electronic speed control switch.
5.1.4 Classification by ambient air temperature:
Resistive load, motor load rated current A
4;6;10;16;25;32
2;4:6;10;16;25
1;2;4;6;1016
a) Switches used in ambient air temperatures between 0°C and 55°C;15
JB/T6526—1999
b) Switches used in ambient air temperatures above 55°C and 85°C; c) Switches used in ambient air temperatures below 0°C. 5.1.5 Classification by number of operating cycles:
a) 10,000 times;
b) 25,000 times;
c) 50,000 times.
5.1.6 According to the mechanism of the switch:
a) Switch with contact mechanism;
b) Switch without contact mechanism.
5.1.7 According to the cooling conditions during use:
a) Switch without forced air cooling;
b) Switch with forced air cooling.
5.1.8 According to function:
a) The code of the automatic reset non-self-locking speed control switch is "WE"; b) The code of the automatic reset closed locking speed control switch is "BE"; c) The code of the automatic reset open locking speed control switch is "DE"; d) The code of the electronic speed control switch is "E"; e) The code of the electronic speed limit switch is "S"; f) The code of the forward and reverse device is "Z". 5.1.9 According to the number of poles:
a) The code of single pole is \1\
b) The code of 2 poles is \2".
5.1.10 According to performance:
a) Half-wave speed control;
b) Full-wave speed control.
5.2 Composition of model
FO-O/OXXO
Derived code (expressed in Arabic numerals) Function code (expressed in Chinese Pinyin 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 Pinyin 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 The number of poles shall be expressed in the numbers specified in 5.1.9. The function code shall be expressed in the letters specified in 5.1.8. The derived code is used for derived products and can be used to indicate the switch handle form, handle size, self-locking form, self-locking size, color, etc. 16
JB/T6526—1999
Example: A push-button electronic speed control 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 single-pole automatic reset closed locking switch. Its model is: FA4-6/1BE. 5.3 Markings on the switch
5.3.1 Markings that should be on the switch:
a) The manufacturer's name or registered 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 line must be marked with a small arrow pointing to the terminal in a conspicuous place next to the terminal. It must also be marked with a wiring diagram;
e) Disconnection mark (only applicable to non-automatic reset switches), usually "0\" is used to indicate the disconnected position, or driven in the "disconnected" direction; f) Operation cycle number mark (the representation method is in accordance with 8.7 of GB15092.1-1994), switches with an operation cycle number of 10,000 times do not require this mark;
g) Ambient temperature limit mark (the representation method is in accordance with 8.5 of GB15092.1-1994), if there is no temperature mark, it means that the rated ambient air temperature range is 0~55℃;
h) 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; j) The switch should not Use Class 1 structural symbols. 5.3.2 The maximum operating voltage (or rated voltage), rated current and power type can be expressed in the following way. The rated current of the motor load is enclosed in parentheses, and 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 to the right is the power type symbol, ~ for AC. For example: 6(4)A250V~ can also be expressed as: 6(42
6(4)/250~ or
5.3.3 The switch mark should 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 marks of small-sized switches can be marked on different surfaces of the main parts. 5.3.4 The marking of the switch should be clear and durable, and the marking The sign must be subjected to 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 sign with a pressure of about 2N/cm. The sign 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 operate normally under the following general environmental conditions: a) The altitude shall not exceed 2000m;
b) Within the rated ambient temperature range;
c) The relative humidity of the air shall not exceed 90% (at 25°C). 6.1.2 The switch shall be manufactured according to the drawings and technical documents approved by the prescribed procedures. 6.1.3 The switch should be in normal use of the power tool Safe and reliable, even if the careless use permitted by this standard occurs in normal use, it will not cause danger to people and the surrounding environment. 6.1.4 Even if the electronic speed control part of the switch fails during use, it will not cause danger to people and the surrounding environment. 6.1.5. The switch should be fully assembled, smooth in appearance, without defects, and uniform in color. 6.2 Electric shock protection
JB/T6526—1999
6.2.1, the switch should have sufficient protection against electric shock, and the human body should not touch the live parts when installed and used according to the method specified by the manufacturer; the human body touchable parts such as the handle and self-locking button of the switch should be made of insulating materials; if made of metal materials, the metal parts and the live parts should meet the requirements of reinforced insulation or double insulation, but switches used for heavy tools are exempted. Verify by observation and relevant tests of this standard. 6.2.2 Paint, ordinary paper, cotton fabric, oxide film or sealant that softens when heated cannot be used as protection against accidental contact with live parts. Verify by observation.
6.2.3 The electrodes of the capacitor in the switch shall not be connected to any accessible metal parts. If the shell of the capacitor is made of metal, additional insulation shall be used to separate the shell from the accessible metal. Verify by observation and relevant tests of this standard. 6.2.4 Except for the heat sink of the semiconductor device, the metal shell of all electronic components on the switch printed circuit board shall not be connected to any accessible metal parts. The creepage distance and electrical clearance between them shall meet the requirements of this standard. Note: All electronic components on the printed circuit board are well encapsulated into a whole with insulating materials, which can be considered to meet the requirements of this clause. Grounding terminal and transition terminal
a) It is allowed to have a terminal for grounding continuity in the switch, but the switch used for such appliances shall not have a device for grounding the switch or its parts;
b) It is allowed to have a wire terminal for transition wiring in the switch;c) The grounding terminal, grounding terminal and other grounding devices shall not be electrically connected to the neutral terminal;d) The connection between the grounding terminal, grounding terminal 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 GB15092.1--1994;e) The grounding clamping device shall not be loosened without using tools. The clamping device shall be fully locked to prevent accidental loosening;f) All parts of the grounding terminal shall not cause corrosion due to contact with the copper or other metal surface of the grounding wire. Verify the requirements of a), b), c), e) and f) by observation. 6.4 Terminals
6.4.1 General requirements
6.4.1.1 The terminals shall be fixed and shall not become loose when the wires are removed or installed. Unfixed terminals are permitted, but shall not interfere with the normal operation of the switch. The test shall be 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 threaded terminals shall be as specified in Table 7.
6.4.1.2 The terminals shall be able to connect the wires specified in Table 2 and the wires shall not slip out of the terminals. The terminals shall be connected to the wires with the maximum cross-sectional area specified in Table 2, the clamping device shall be tightened with the torque specified in Table 7, and then the terminals shall be connected to the wires with the minimum cross-sectional area specified in Table 2. After the test in 6.4.2.2, the wires shall not slip out of the terminals. Table 2 Current and wire cross-sectional area
Resistive current carried by terminal1
6≤10
25<≤32
Cross-sectional area
Terminal specification number
Cross-sectional area
Terminal specification number
Switch terminals used to connect flexible cables or flexible wires should ensure that when part of the core wire comes out, it will not touch live parts of different polarities6.4.1.3
or accessible metal parts, nor should it cause a short circuit between terminals that are electrically connected only through the action of the switch. 18
The test method is as follows:
JB/T6526—1999
Strip off 8mm of insulation at the end of the soft wire with the minimum cross-sectional area specified in Table 2, leaving one wire outside, and insert and clamp the rest in the terminal. Without tearing the insulation, turn the wire left outside to all possible directions. If there is a grounding terminal in the switch, the wire left outside must also be turned to all possible directions. 6.4.1.4 The selected terminal must comply with the relevant provisions of GB15092.1, and the terminal connected to the power supply must be a screw-type terminal.
6.4.2 Screw-type terminal
6.4.2.1 Form and size of screw-type terminals a) The type of screw terminals is shown in Figure 1. The size should comply with the requirements of Table 3; A-fixing component, B-washer or pressure plate; C-clamping plate; D-wire placement space; E-pin; F-wire; G-maximum gap between parts that constrain the wire Figure 1 Screw terminals
Table 3 Parameters of screw and bolt terminals
Connectable wire cross-section area
0. 5~]. 0
0. 75~1. 5
0. 5~1. 0
The maximum clearance between the screw head for placing the conductor and the threaded nail support in the threaded screw hole on the nominal straight screw for zero thread
The minimum value of the minimum length
The minimum value of the space dimension D
b》The types of bolt terminals are shown in Figure 2, and the dimensions shall comply with the provisions of Table 3;
Minimum difference in nominal diameter
Screw head
JB/T6526—1999
A-fixing component; B-washer or pressure plate; C-clamping plate; D-conductor securing space:
E-screw inspection; F-conductor; G-maximum clearance between parts that constrain the conductor Figure 2 Bolt terminals
The dimensions of the screw and the washer or pressure plate used in the bolt terminal shall comply with the provisions of Table 4. Table 4 Sizes of washers or pressure plates used in screw terminals Nominal diameter of thread
Maximum difference between thread diameter and inner diameter of washer circle Www.bzxZ.net
Minimum difference between thread diameter and outer diameter of washer circle
c) The type of column terminal is shown in Figure 1 of GB15092.1-1994, and the dimensions shall comply with the provisions of Table 5; Table 5 Dimensions of column terminal
Conductor cross-sectional area ||tt ||Minimum value of nominal diameter of screw
Wiring hole size
d) The type of lug terminal is shown in Figure 3, and the size should comply with the requirements of Table 6 mm
Minimum value of thread length in column
A—locking device, B—electric lug: C—screw or bolt; D—fixed part; g—the distance between the hole edge and the two sides of the clamp; f—the minimum distance between the hole edge and the fixed part Figure 3 Lug Terminal
Minimum distance between the wire end and the clamping
screw
Circuit current
10≤16
Minimum value of the nominal thread diameter
JB/T6526—1999
Size of lug terminal
Maximum difference between the thread diameter and the lug
aperture diameter
Between the hole edge and the connection edge
The minimum distance g
The minimum distance f
between the edge of the hole and the surrounding part
6.4.2.2 The screw-type terminal should be able to reliably clamp the wire on the metal surface. This is verified by the following test. The terminal is connected to the wire with the minimum and maximum cross-sectional area specified in Table 2 respectively. It is tightened with 2/3 of the torque shown in the corresponding column of Table 7. If the screw is a slotted hexagon head screw, it is tightened with 2/3 of the torque shown in the second column of Table 7. Each wire is subjected to the axial tension specified in Table 8 for 1 min. The tension should not be applied suddenly. The torque for tightening the screw in Table 7
Nominal thread diameter
The wire should not be significantly displaced in the terminal.
Applicable to headless screws that do not protrude out of the hole after tightening and other screws that cannot be tightened with a screwdriver with a blade width larger than the screw diameter. Applicable to other screws that are controlled by a screwdriver. Applicable to screws or nuts that are not tightened with a screwdriver. Table 8
Terminal specification number
Tensile force of threaded terminals
Except for column-type terminals, other types of threaded terminals shall be equipped with spring washers to prevent loosening. 6.4.2.3
6.4.2.4The ends of the screws that press the wires in column-type terminals shall be smooth and shall not have flanges or sharp corners that may damage the wires. After the wire damage test, the wire clamping parts shall not break or show obvious cracks. The wire damage test uses the mechanism shown in Figure 4 (the H value in Figure 4 is specified in Table 9). The soft wire is clamped with the torque specified in Table 7. The wire is subjected to the tensile force specified in Table 8. The wire is rotated smoothly within 5s for one circle, and then rotated in the opposite direction for one circle within 5s. The wire should not be subjected to torque during the rotation process. After the test, the wire shall not show obvious cracks. Table 9 Conductor cross section and H value
Conductor cross section
250±10
500±10
750±10
JB/T6526-1999
100±5
1-conductor; 2-turntable; 3-weight
Figure 4 Schematic diagram of conductor damage test
6.4.3 Screwless terminal
Screwless terminal adopts spring, wedge, eccentric block, cone or equivalent components and similar methods to realize electrical connection. No special tools are required for connection and disconnection.
6.4.3.1 The type of screwless terminal is shown in Figure 6 of GB15092.1--1994. The size is not specified. The cross-sectional area of ​​the soft wire allowed to be connected shall not exceed 2.5mm, and the cross-sectional area of ​​the hard wire shall not exceed 4mm. 6.4.3.2 When connecting wires to threadless terminals, the wires should be easy to insert; when pulling out the wires, in addition to pulling the wires, an additional operation must be performed to pull the wires out of the terminal. If the wires need to be pulled out with the help of tools and the wire hole and the tool hole are separate, the wire hole and the tool hole must be clearly different.
For terminals that connect multiple wires, each wire should only be inserted separately, and the operation of clamping the wires has nothing to do with other wires and cannot affect the clamping of the wires; when pulling out the wires, each wire can be pulled out separately or at the same time. 6.4.3.3 Threadless terminals should have a stopper to block the wires at the terminal to prevent excessive insertion of the wires. 6.4.3.4 When the insulating material may deform or shrink, and the elastic parts cannot maintain sufficient contact pressure, the contact pressure should not be transmitted through the insulating material (materials such as ceramics and pure mica can be considered as materials that will not deform or shrink). 6.4.3.5 The threadless terminal should allow the wire to be reliably clamped between metal surfaces. If the current of the connecting circuit does not exceed 0.2A, one surface is allowed to be non-metallic. After the following test, the terminal should not be damaged to affect its continued use. The thickest and thinnest wires allowed for connection are tested successively. a) For threadless terminals that can only connect hard wires, first use a single-core wire to plug and unplug 5 times, and then use a multi-strand twisted wire to plug and unplug once; b) For threadless terminals that can only connect soft wires, use a soft wire to plug and unplug 5 times; c) For threadless terminals that can connect both hard wires and soft wires, use a hard wire and a soft wire to plug and unplug 5 times respectively. In the above-mentioned plugging and unplugging situations, except for the fifth plugging and unplugging with the wire plugged and unplugged for the fourth time, a new wire is used for each plugging and unplugging. Each time, the wire should be inserted as far as possible to the bottom, and the wire should be twisted 90° after insertion before it can be pulled out. After the fifth insertion, the axial direction of the wire bears the tensile force in Table 8 for 1 minute. The wire shall not come out of the terminal and the tensile force shall not be applied suddenly. 22
JB/T6526—1999
Terminals for connecting multiple wires shall be able to reliably clamp all wires from one to the maximum number specified. 6.4.3.6 When threadless terminals clamp wires, they shall not cause excessive damage to the wires. Test according to the method in 6.4.2.4. 6.4.3.7 Threadless terminals shall have sufficient aging resistance and shall comply with the provisions of 11.1.1.3.4 in GB15092.1-1994. 6.4.4 Flat quick-connect terminals
Flat quick-connect terminals shall comply with the provisions of 11.1.2.4 in GB15092.1-1994. The fan-type quick-connect terminal should have sufficient current overload capacity, and the overload current is 1.5 times the maximum rated current of the switch. Under room temperature conditions, 45 minutes of power on and 15 minutes of power off constitute a cycle. The terminal should be able to withstand 500 cycles of overload current test. After the test, the heating test shall be carried out according to the provisions of 6.10. The temperature rise value shall not be greater than 55K. Then the contact voltage drop shall be measured. The overload test current shall be passed. The measured contact voltage drop shall not be greater than 2 times before the overload test. 6.5 Structure
6.5.1 After the switch has undergone the durability test, the creepage distance and electrical clearance on the supplementary insulation or reinforced insulation shall not be reduced to less than the specified values ​​in Table 18 of GB15092.1-1994. When the switch is in normal use, any wire, screw, nut, washer, spring, connector and similar parts on it, if it may become loose or fall off from the original position, shall also have creepage distance and electrical clearance not less than GB15092.11994 half of the value specified in Table 18. Note
Parts fixed by screws and nuts that will not be disassembled during maintenance and washers with locking properties can be considered as not loose or falling out. Springs or elastic parts can also be considered as not loose or falling out if they meet the requirements of 6.10 and 6.13. Soft wires fixed in terminals are considered to be easy to loosen or fall out unless additional fixing measures are taken within 3cm. Rigid wires can remain in their original position when the terminal screws are loose, so no additional fixing measures are required. 6.5.2 The rigidity, fixing and insulation of the internal wiring of the switch should be such that the creepage distance and electrical clearance will not be reduced below the specified value during normal use. If the internal wiring is insulated, the insulation should not be damaged during installation and normal use. Check by observation.
6.5.3 The cover or cover plate on the switch should be firmly fixed and cannot rotate. When the switch is installed on an electric tool for use, the operating part of the switch must be removed with a tool.
6.5.4 The operating part indicating the operating position after maintenance should not be installed in the wrong position. If the parts used for additional insulation or reinforced insulation are missing or installed in the wrong position, the switch should not work or be obviously incomplete. 6.5.5 The switch should have a certain vibration resistance performance. During and after the vibration test, the switch should not have any of the following situations: a) Parts break or cause unsafe deformation; b) Fasteners loosen or fall off, springs or other parts fall off; c) Switch operation fails;
d) Moving and static contacts jump:
e) Switches with self-locking mechanisms automatically release the self-locking. The vibration test uses three samples fixed on the vibration table in three states: vertical, horizontal and lateral. The bidirectional amplitude of the vibration table is 1.5mm, the vibration frequency is 50Hz, and the switch contacts are in the closed state and vibrate for 1h. In order to observe whether the contacts jump during the test, the circuit of Figure 5 can be used. Observe with an oscilloscope. Irregular pulse waves shall not appear continuously. The cumulative number of irregular pulse waves in the whole test shall not exceed 10 times.
6.5.6 The printed circuit board and electronic components in the switch shall be firmly fixed, and their insulation value shall not be reduced below the specified value during normal use. Check by observation.
6:5.7 The distribution of electronic components on the printed circuit board in the switch, the creepage distance and electrical clearance between them shall comply with the provisions of the relevant standards. 6.5.8 The forward and reverse device of the bidirectional speed regulating switch shall be structurally guaranteed to be converted only when the current is disconnected. 6.5.9 The speed regulating switch for electric tools should have a contact disconnecting mechanism. For the speed regulating switch without a contact mechanism, it should be connected in series with an ordinary switch with a contact mechanism and used in the electric tool.
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