GB 9378-1988 Safety requirements for audio, video and pulse equipment in radio and television studio systems
Some standard content:
1 cited
National Standard of the People's Republic of China
Safety requirements for video-audfo and pulse equipment of broadcasting television studio system1.1 Scope
GB 9378-88
1.1.1 This standard applies to the following AC and DC powered indoor (in-car) equipment used in radio and television studio systems: a.
Processing equipment (including program production and broadcast control equipment): pulse and timing equipment;
b.
c.
d.
Image signal source equipment:| |tt||Audio broadcast control equipment:
Equipment used in combination with the above equipment;
e.
f.
The above equipment is equipped with necessary auxiliary devices for work. Accessories, spare parts. This standard does not apply to the following equipment:
1.1.2
Equipment with safety insulation structure using double insulation or reinforced insulation without protective grounding measures, b.
Equipment with independent safety requirements Equipment, such as monitors, cameras, video recorders, microphones, speakers, audio power amplifiers, etc. 1. 2 Purpose
1.2.1 This standard aims to protect:
a.
b.
Electric shock:
High temperature, book fire and others harm.
1.2.2 This standard specifies the design and manufacturing requirements, and in some places also specifies test methods. The purpose is to ensure that professionals safety. a.
Ensure the safety of professional personnel h.
. 1.2.3 This standard specifies certain tests where appropriate to verify whether the equipment complies with the safety requirements of this standard under normal operating conditions and when operating under the fault conditions defined in Article 3.2. In order to check whether the design of the equipment complies with the safety requirements of this standard, these tests should be carried out on representative equipment. 1.2.4 In addition to the type inspection, this standard also applies to delivery inspection, inspection after changes to equipment components, and inspections conducted at appropriate intervals to ensure the safety of the equipment throughout its life cycle. Terminology
1 Professionals and Operators
1.1 Professionals
Anyone who has received professional education, has professional knowledge and experience, and can identify the possible hazards of the equipment they operate and use. , and have emergency response skills approved by the Ministry of Electronics Industry of the People's Republic of China on April 26, 1988 and implemented on December 1, 1988
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, such as artificial respiration, etc. 2.1.2 Operators
GB 9378--88
Personnel who have received professional technical and safety technical training related to the tasks they undertake, and have sufficient understanding of the dangers that may occur if operations are not carried out in accordance with the procedures.
2.2 Parts and Accessories
2.2.1 Terminal device
is a component used to connect external conductors or other equipment. A terminal device can have several terminal contacts. 2.2.2 Protective ground terminal
refers to the terminal that must be connected to the ground component for safety reasons. 2.2.3 Functional ground terminal
refers to a terminal that needs to be connected to a ground component for reasons other than safety. 2.2.4 Remote control device
refers to a device that controls equipment remotely.
2.2.5 Plug-in unit
Replaceable part of the device. It is connected to the host using a plug or socket to provide specific functions. 2.3 Electricity
2.3.1 Rating value
refers to the quantity specified by the manufacturer when designing the equipment. 2.3.2 Grid power supply
refers to a power supply that does not only supply power to a system composed of one piece of equipment or several pieces of equipment as mentioned in Article 1.1.1. 2.3.3 Rated power supply voltage
refers to the power supply voltage specified by the manufacturer for the equipment in the design. 2.3.4 Safety extra-low voltage
A voltage with an effective AC value not exceeding 50V between conductors or between conductors and ground. In the circuit, use a safety isolation transformer or a converter with independent windings to isolate it from the grid power supply. Note: ① DC is still under study.
②In the definition, it is assumed that the transformer or converter operates at the rated supply voltage, and this voltage limit should not be exceeded under full or empty conditions.
2.4 Structure
2.4.1 Barrier
Guides the shortest distance measured in space between electrical components. 2.4.2 Creepage distance
refers to the shortest distance measured along the insulation surface between electrical components. 2.4.3 Manual
refers to the kind of operation without tools, coins or any other objects. 2.5 Inspection
2.5.1 Type inspection
refers to a set of comprehensive tests conducted on several representative prototypes to determine whether the manufacturer can produce equipment that meets this standard.
2.5.2 Delivery inspection
is a test conducted on all equipment in the same delivery batch. 2.6 Safety
2.6.1 Accessible parts
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GB 9378-88
The gap between the standard finger test rods or the finger test rods The part smaller than the specified value (see 5.1). The accessible area of ??the non-conductive part can be considered as the conductive layer covering the non-conductive part (see 5.1). 2.6.2 Live parts
Parts that will cause obvious electric shock when touched (see 5.2). 2.6.3 The part directly connected to the grid power supply
When the equipment is not grounded, if a part of the equipment is connected to any pole of the grid power supply and the passing current is equal to or greater than 9A, then this part is considered to be connected to the grid power supply. direct connection. The 9A current is selected based on the minimum fusing current of the 6A fuse. During the test to determine whether the component is directly connected to the grid power supply, the fuse of the equipment should not be short-circuited. Therefore, if a component is connected to the mains supply via a fuse with a rating less than 6 A, the component is not considered to be directly connected to the mains supply. 2.6.4 The conductive connection part to the grid power supply
When the equipment is not grounded, the equipment part is connected to either end of the power supply through a 2k resistor. If there is a current greater than 0.7mA (peak value) on the resistor, it is considered that the Some parts are electrically connected to the grid power supply. 2.6.5 Basic insulation
refers to the insulation added to provide basic protection against electric shock to live parts. 2.6.6 Supplementary insulation
An independent insulation added in addition to basic insulation to prevent electric shock when the basic insulation fails. 2.6.7 Double insulation
Insulation consisting of both basic insulation and supplementary insulation. 2.6.8 Reinforced insulation
is a basic insulation with improved mechanical and electrical properties. It has the same level of electric shock resistance as double insulation. 3 Normal working conditions and fault conditions
This chapter gives the range of normal working conditions and fault conditions under which the equipment can work without danger to operators including professionals and their guidance. The equipment shall meet the safety requirements of this standard under the normal operating conditions given in Article 3.1 and when the initial fault conditions listed in Article 3.2 are added.
The test should be carried out under the following normal atmospheric conditions: temperature: 15~35℃;
relative humidity: 45%~75%*
air pressure: 86~106 kPa.
3.1 Normal working parts
Normal working conditions refer to the test conditions obtained by the most unfavorable combination of the following conditions. Supply voltage and frequency should be within the design range of the equipment. a.
For AC powered equipment, the power supply voltage waveform should be a basic sine wave, and its waveform is as shown in Record D (Supplement). b.
·c. For AC and DC equipment, the two power supplies must be powered separately. d. The protective ground terminal or contact should be reliably connected to the ground. Except for the grounding terminal designed for manual wiring, other grounding terminals should be reliably grounded except that they are not firmly connected to the ground. If there are doors, covers or other protective objects, they should be fixed in the specified position and can only be opened or removed unless they are designed to be opened or removed manually.
The equipment works in any position specified by the design. f.
The equipment can work under any input signal conditions specified by the technical conditions. g.
Except for the power supply voltage conversion device, the control knobs accessible to the operator are in any position when manually adjusted. h.
. Equipment driven by motors operates under any load conditions specified by the design. 465
3.2 Fault conditions
GB 9378-88
Equipment working under normal operating conditions, when one of the following initial faults a~i occurs, and subsequently causes associated faults , that is, under fault conditions, the simulated initial faults should be added in appropriate order. a. If the creepage distance is less than the value given in Appendix A (Supplement) (unless its insulation meets the requirements of Article 5.6), the creepage distance is short-circuited. b. If the gap is smaller than the value given in Appendix A (Supplement), the gap is shorted. c | Mismatch at the output exceeds specified value, including open circuits and short circuits. d.
e.
The moving parts of the rotating or linear motion device are stuck due to mechanical failure. Cooling unit failed. | |tt | Short circuit in the power transformer secondary winding (any current limiting impedance connected directly to the secondary winding will still operate). The output of the power supply unit is short-circuited.
i.
j.
The three-phase power supply is missing a phase.
4 Components, structures, markings
The purpose of this chapter is to ensure that when designing and manufacturing equipment, it is necessary to ensure the safety of personnel throughout the entire life of the equipment. Where no test method is given, inspection shall be carried out by inspection or appropriate functional test. 4.1 Optical components
4.1.1 General requirements
a. The components used in the equipment should comply with the technical requirements of the components. b. The load of components is not allowed to exceed its rated value under normal operating conditions, and should not be exceeded as much as possible under fault conditions. c. For components that operate beyond the rated value under fault conditions, if it is known that they have been verified by appropriate tests to meet safety requirements, no further tests are required. Otherwise, the component shall be tested inside the equipment or outside the equipment under conditions equivalent to its use within the equipment. The number of components to be tested shall be determined by negotiation between the manufacturer and the user. 4.1.2 Connector
a. The design and selection of connectors must ensure that no harm will be caused by misconnection during use. For example: circuit connectors for non-power circuits cannot be used as grid power connectors. The grid power connector cannot be used for other purposes, such as safety extra-low voltage power supply or signal circuits.
b． The structure of the connector should prevent the bare core of the access wire from passing out of the connector and causing the bare core to come into contact with other components. c. The clearance and electrical distance between connectors and connection points in the equipment used for auxiliary purposes (such as monitoring) and other circuits should be at least twice the values ??given in Appendix A (Supplement). d. Live parts of live connectors shall not be accessible parts. 4.1.3 Switch
a. Under normal working conditions, circuit breakers and manual switches used in grid power supplies and other power circuits should have good on-off capabilities. The circuit breaker should also have good switching capabilities under fault conditions. b. Switches (including circuit breakers) should be able to disconnect all poles of the equipment from the power supply at the same time to ensure the safety of the equipment. c. Equipment powered by mains power must have a power switch (except in special circumstances). 4.1.4 Fuse
The fuse element in the fuse selected for design should be encapsulated and should have sufficient fusing capacity to safely cut off the circuit. Its rated current value should be marked near the fuse. The fuse should comply with the requirements of Article 14.5.2 of GB8898 "Safety Requirements for Household and Similar General-purpose Electronics and Related Equipment Powered by Grid Power Supply".
166
4.2 Structure
4.2.1 General requirements
GB 9378—88
a. Structural parts within the equipment should be made of non-flammable materials wherever possible and should be of sufficient strength to ensure safety. Under normal working conditions, fault conditions and user maintenance, there is no risk of fire, electric shock or personal injury. b.
All metal parts, unless the metal is corrosion-resistant, must take anti-corrosion measures. c.
should be assembled to prevent the insulation between circuit components conductively connected to the grid power supply or equivalent circuits and accessible conductive parts due to screws, wires, etc. Accidental loosening and short circuit. e. When designing, the strength of wire connection points that are subject to mechanical stress should not rely on welding, but should have appropriate clamping devices. f. The anti-loosening requirements of screws can be checked by visual inspection and the relevant test items and test methods specified in Chapter 17 of GB8898.
4.2.2 Handle strength
To ensure safety, all handles, handle fixings and shell parts that fix the handle used to support and carry equipment should be able to withstand four force times the weight of the device without being damaged. 4.2.3 Creepage distance and clearance
a. In power circuits (primary) with risk of electric shock, the requirements for creepage distances and clearances between uninsulated parts and the following parts are in accordance with Appendix A (Supplement):
Uninsulated power circuits of opposite polarity Part; accessible metal part;
An uninsulated part outside the power circuit that may cause an electric shock hazard due to breakdown. b. In addition to the internal insulation of components, additional insulation is required when the clearance between uninsulated live parts of opposite polarity, or between such parts and accessible metal parts, does not meet the requirements of Appendix A (Supplement). Isolation is provided by partitions or sleeves of fibrous or polymeric material. These plates or casings shall meet the following conditions: The partitions or casings shall have corresponding mechanical strength if they are likely to be subject to mechanical damage: The partitions or casings shall be able to be reliably fixed: The minimum thickness of the partitions or casings ( 7 mm).
c. Where creepage distances in equipment are less than the values ??given in Appendix A (Supplement), the insulating material must be free of leakage traces and non-flammable. For materials other than ceramics, the comparative tracking index (CTI) should adopt the test method given in GB4207 "Determination of comparative tracking index and tracking resistance index of solid insulating materials under humid conditions" to make sure. If the tracking index is equal to or greater than 175, the material can be considered to be free of leakage traces. The flammability of insulating materials should be tested using the tests given in GB5169 "Fire Hazard Test for Switch Electronic Products". d On relays, plugs, sockets, printed circuit boards, semiconductor devices, micro-components and similar devices, a smaller creepage distance is allowed as long as they comply with the respective technical specifications. 4.2.4 Battery installation
The battery installation location should maintain good ventilation conditions to eliminate harmful gases and gases, and ensure that when the battery electrolyte leaks out, it will not damage other components or damage the battery. personnel. 4.3 Marking
4.3.1—General requirements
a. Safety-related markings should remain clear and legible throughout the life of the equipment. Check by visual inspection and the following tests.
The mark should not be wiped off by gently wiping it with a cloth soaked in gasoline, alcohol or water. b. Markings should be easily identifiable and cannot be misunderstood when using the equipment. c. Marks are allowed to be used in combination with symbols and words. The text symbols for various quantities and units should comply with GB3100 "International System of Units and Their Applications" and GB3101 "General Principles of Quantities, Units and Symbols". Graphic symbols should comply with GB5465.1~5465.2 "Graphic Symbols for Electrical Equipment".
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4.3.2 The equipment should have the following marks and their contents: GB 9378-88
a. Factory identification mark: manufacturing name and registered trademark. bDevice name tag: model or name.
Precautionary markings: such as text "Danger", "Warning", "Caution", etc. Symbols can also be used: for example, the dangerous voltage symbol is represented by "[}\, and the c.
warning symbol is represented by ".
Power supply mark
d.
Power supply properties: AC is represented by the symbol "～"; DC is represented by "" or "一", and the symbol "\" is used for both AC and DC. Indicates the rated power supply voltage value or voltage range that can be used. If safety is related to the power supply frequency, the rated power supply frequency should also be marked:
e.
f． Ground terminal marking: It can be represented by symbols. For example, protective ground terminals can be represented by the symbol "国"; functional ground terminals can be represented by the symbol "work".
g, test terminal mark: name or code. h. Operating instructions mark.
i, the identification mark of "on" and "off" in the switch. The above markings shall be inspected by visual inspection.
5 Protection against electric shock
The purpose of this chapter is to ensure that the design and manufacture of equipment ensures prevention of electric shock during the life of the equipment. Where no test method is given, visual inspection shall be applied and the functions shall be used appropriately. Test to verify. 5.1 Accessible parts
Accessible parts should not be charged. In order to determine whether a certain part is accessible, test according to the test methods specified in GB4793 "Safety Requirements for Electronic Measuring Instruments" 9.1 and 9.5.4a. 5.2 Live parts
In order to determine whether a certain part is live, test it according to the test method specified in GB4793 Article 9.2. 5.3 The outside of the equipment
5.3.1 The operating shaft
The operating shaft is not allowed to be electrified and shall be tested according to the test method specified in 5.2. 5.3.2 Knobs, handles
Knobs, handles, etc. should be made of insulating materials, unless they are connected to controlled components or components through insulating shafts or insulating supports, or these components or components have been Test the protective impedance specifications, see Chapter 14 of GB4793. 5.3.3 Ventilation holes
When designing the ventilation holes and other holes above the live parts, suspended debris entering the equipment should not come into contact with the live parts inside the machine. The test method shall be tested according to the test method specified in GB4793 Article 9.3.3 . 5.3.4 Pre-adjusting device
If a screwdriver or other tool is required, the risk of electric shock should not be incurred when adjusting the pre-adjusting device through the small hole, and the tool cannot become a live body. Use the test method specified in 5.2 for inspection.
5.3.5 Power supply voltage adjustment
Changing the power supply voltage or power supply category manually should not cause the risk of electric shock and should be tested by the test method specified in Article 5.2. 5.3.6 Terminal device
Functional grounding terminals and protective grounding terminals should not be charged, and should be tested according to the test method specified in Article 5.2. a.
The terminals connected to the live parts in the machine should not be accessible parts and should be tested using the test method specified in Article 5.1. h.
In order to prevent electric shock due to energy storage, the terminal connected to the internal capacitor should not be charged after cutting off the power supply for 10$. Use the test.c.
468
method specified in 5.2.
5.3.7 Remote control device
GB 9378--88
The buttons, pull keys, push-pull rods, toggles, etc. on the remote control device and the indicator lights inside them (if any ), its maximum control voltage should be less than the safety extra-low voltage.
5.3.8 Devices with detachable parts
Manually remove the cover or other detachable parts (such as the exposed parts after inserting the unit should not be live, and may become accessible during normal operation) None of the parts should be electrified, even if a key or other tool is used to open the cover or the accessible part behind the door, it should not be electrified. Use the test method specified in 5.2 to test
5.3.9 All under normal conditions. When the cover needs to be opened during work to make parts powered by voltages above 1kV or floating voltage accessible, the cover and accessible parts must be marked with a red lightning symbol (see 4.3.2c) 5.4 Wiring || tt||a. All wires and cables should be adequately protected (including additional insulation measures) from possible mechanical damage under normal operating conditions
Use adequate insulation. Structural isolation, wires used for power grid connection inside the equipment should be protected from possible contact with other wires and other components inside the equipment C. The cable termination device should ensure that the electrical connection of the cable is not affected by mechanical stress and that the cable is protected from wear and tear. 5.5 Grounding
5.5.1 Protective grounding terminal
It should be reliably connected to the protective ground terminal, and the following measures should be taken. a. Equipment connected to fixed power lines should use a separate protective ground terminal and should be close to the power supply terminal of the power grid, marked with the symbol "solid". Be marked. The material used for the grounding terminal should be consistent with the grounding copper conductor. The grounding terminal must not be loosened by hand.
b. Equipment with non-detachable cords or cables. The requirements of Article 1 also apply.
In addition, the cord or cable connecting the equipment to the mains power supply shall contain an insulated grounding conductor of appropriate cross-section and the color shall be consistent with the requirements of Appendix C (Supplement) are consistent with each other and should be connected to the protective ground terminal of the equipment. If equipped with a plug, this wire should be connected to the protective ground terminal of the plug.
c. Equipment equipped with a power grid connector. ||Make sure that the power supply connector of the device has a protective grounding contact, which should be an integral part of the connector. The protective grounding contact should be made before plugging the power supply into the connector. On the contrary, the protective grounding contact should be made after unplugging the power supply. The protective grounding, protective grounding connector and protective grounding contact can be disconnected and cannot be used for any other purpose. 5.5.2 Protective grounding
The implementation of protective grounding should not rely on the conductivity of the chassis frame. Instead, specially laid conductors with relatively low impedance should be used for connection to ensure that accessible parts are electrically safe under normal operating conditions and under fault conditions. Conductors used for protective grounding cannot be used for other purposes. Any purpose. When in doubt, measure the electrical value between the accessible conductive parts and the protective ground terminal. The voltage drop across the resistor should not exceed 12.5V. , the corresponding resistance value does not exceed 0.50. For this test, connections to accessible conductive parts shall be ensured and shall be capable of carrying the current specified above. 5.6 Basic safety test
The safety of the equipment against electric shock is tested by the basic safety test. The basic safety test includes three tests: insulation resistance, voltage, and leakage current. The basic safety test of the equipment is carried out according to the following steps. . 5.6.1 Moisture pretreatment
Perform moisture pretreatment according to this article, and then immediately carry out inspection according to the test methods specified in 5.6.3 and 5.6.4. 469
GB 9378-88
During the entire process of moisture pretreatment, the equipment should be in a non-working state. If necessary, remove electrical components, covers and other parts that can be manually removed. Pre-treatment for moisture along with major components. The conditions for moisture pretreatment are: relative humidity 91% ~ .95%, temperature t (40-2℃) for 48 hours. In order to avoid condensation and water condensation, the equipment should be kept under 1 (t+4)" for at least 4h before moisture pretreatment. Note: During delivery inspection, moisture pretreatment is not performed. 5.6.2 Circuit grouping || tt||In the following tests, the circuits of the equipment are divided into two groups, each group of circuits has its own safety requirements. a. Circuits that are conductively connected to the power supply and other circuits that are equivalent to this. |tt||This standard stipulates that gas discharge, vacuum and semiconductor paths should generally not impose insulation requirements. 5.6.3 Insulation resistance test
The insulation resistance test should be performed after the equipment is taken out of the humidity chamber and the equipment is in a non-working state. , and perform it with the power switch turned on.
The equipment belongs to the circuit specified in Article 5.6.2a.
The specified circuit and the chassis (or accessible conductive parts). Apply 500V DC voltage between them, wait for the megohmmeter reading to stabilize for 5 seconds, and then read the insulation resistance value
For a circuit with an operating voltage not exceeding 500V, the insulation resistance value shall not be less than: the basic insulation of the equipment is 2MQ:| |tt||For circuits with additional (protective) insulation of 5MQ, the operating voltage exceeds 500V, the above insulation resistance value must be multiplied by a coefficient, which is equal to the operating voltage divided by 500V. b. The equipment belongs to 5.6. For circuits specified in Article 2 b, apply a DC voltage of 100V between the circuit and the chassis that is not connected to accessible conductive parts. After the megohmmeter reading is stable for 5 seconds, read the insulation resistance value. For circuits with a voltage not exceeding 500V, the insulation The resistance value should be no less than 1Mn. For circuits with an operating voltage exceeding 500V, the above insulation resistance value should be multiplied by a factor equal to the operating voltage divided by 500V.4 voltage test
. The voltage test should be carried out with the equipment in a non-working state and its power switch turned on. The test voltage used is as specified in Table 1.
b: The test voltage should be a basic sine wave, see Appendix D (supplement), the frequency is 45 ~ 65Hz, the test voltage should gradually rise to the specified value to avoid transients, maintain the specified voltage for 1 minute, and then drops smoothly to zero. Breakdown and flying orphans are not allowed in the test, and corona discharge effects and similar phenomena are not considered. Usually, even if a resistor is connected to the circuit where arcing occurs, the output current of the test voltage device is 5mA, which is sufficient to observe breakdown. d. When the test voltage does not exceed 2kV, the number of tests of the equipment is determined as needed, and each test is conducted at 100% of the test voltage. When the test voltage exceeds 2kV, the equipment is only allowed to be tested twice at 100% test voltage. If the test is to be carried out again, it should be carried out at 80% of the test voltage.
e． Voltage test should also be carried out during delivery inspection. The delivery inspection only checks the circuits and accessible conductive parts of the live terminal device. 1. During delivery inspection, the anti-interference capacitor between the power conductor and accessible conductive parts should not be open circuit. If these capacitors cannot be tested with AC voltage, a DC voltage equal to 1.4 times the AC test value may be used. g. During the voltage test, semiconductor devices that may be damaged due to the influence of the electric field can be open-circuited, short-circuited or replaced with analogs during the type inspection. During delivery inspection, if there are such devices in the circuit, the test voltage should be reduced to half of the value specified in Table 1, but not less than 1kV. h. When there are several rated voltages, the test voltage should be selected according to the highest rated voltage. 170
Sequence
1
2
No.
Insulation under test
Between 5.6.2 a circuits||tt| |5.6.2 between a circuit and the chassis
(accessible conductive parts)bzxZ.net
5.6.2 between a circuit protection screen
between knock
GB 9378--88
Table 1 test voltage
rated voltage or insulation voltage (U,)
DC or sine wave AC
effective value
V
0～60
>60~~130
>130～250
>250～660
>660-~1 000||tt ||>1 000~~1 500
>1 500~~2 000
>2 000
AC bee value or composite voltage
V||tt| |0~85
>85~184
>184~354
354-933
>933~1 400
>1 400-2 100
>2 100—2 800
>2800
test
test
voltage
kv
0.5| |tt||1
1.5
2
3
4
5
slightly larger than (2U.→1000V)|| During the voltage test, the integral dry volts of tt||
1 (2Us +200 V) or 500V
5.6.2 b circuit and the chassis (such as accessible conductive parts), These circuits shall be connected to each other: during tests 1 to 3. These circuits shall also be connected to the chassis. Dare its larger value
Note: Insulation voltage (U:) refers to the voltage applied to the insulation under the reference test conditions (DC or AC voltage, which is the sum of the two when synthesizing electric jade). 5.6.5 Leakage current test
8． Place the device on an insulated table and operate it at 1.1 times the rated supply voltage until the temperature reaches equilibrium. If there is a different voltage adjustment, 1.1 times the highest rated voltage should be applied. b. Use the circuit in Figure 1 for testing. Place the transfer switch on each pole of the power supply in turn and measure the AC peak value or DC value, which should not be greater than 5mA.
c． Ammeter to measure leakage current. Its nominal internal resistance is 2kQ (series resistor included if required). d. When the equipment has a functional ground terminal, it can be tested with a voltmeter with an internal resistance of about 50k2, and the measured voltage does not exceed the safety extra-low voltage limit.
Figure 1
1-Accessible conductive parts: 2 Grid power supply: 3--Transfer switch; 4-Protective grounding terminal
6 Protection against high temperature, fire and other hazards||tt ||The purpose of this chapter is to ensure that personnel are not susceptible to injury from overheated components during normal operation of the equipment, and that high temperature conditions that can cause fire or other hazards do not occur. This chapter also includes various other hazards that should be avoided by the design of the equipment. Where no test is provided, inspection should be carried out by visual inspection, and functional tests should be used where appropriate. 6.1 High temperature
6.1.1 Allowable temperature rise under normal working conditions 471
1x the maximum rated voltage. b. Use the circuit in Figure 1 for testing. Place the transfer switch on each pole of the power supply in turn and measure the AC peak value or DC value, which should not be greater than 5mA.
c． Ammeter to measure leakage current. Its nominal internal resistance is 2kQ (series resistor included if required). d. When the equipment has a functional ground terminal, it can be tested with a voltmeter with an internal resistance of about 50k2, and the measured voltage does not exceed the safety extra-low voltage limit.
Figure 1
1-Accessible conductive parts: 2 Grid power supply: 3--Transfer switch; 4-Protective grounding terminal
6 Protection against high temperature, fire and other hazards||tt ||The purpose of this chapter is to ensure that personnel are not susceptible to injury from overheated components during normal operation of the equipment, and that high temperature conditions that can cause fire or other hazards do not occur. This chapter also includes various other hazards that should be avoided by the design of the equipment. Where no test is provided, inspection should be carried out by visual inspection, and functional tests should be used where appropriate. 6.1 High temperature
6.1.1 Allowable temperature rise under normal working conditions 471
1x the maximum rated voltage. b. Use the circuit in Figure 1 for testing. Place the transfer switch on each pole of the power supply in turn and measure the AC peak value or DC value, which should not be greater than 5mA.
c. Ammeter to measure leakage current. Its nominal internal resistance is 2kQ (series resistor included if required). d. When the equipment has a functional ground terminal, it can be tested with a voltmeter with an internal resistance of about 50k2, and the measured voltage does not exceed the safety extra-low voltage limit.
Figure 1
1-Accessible conductive parts: 2 Grid power supply: 3--Transfer switch; 4-Protective grounding terminal
6 Protection against high temperature, fire and other hazards||tt ||The purpose of this chapter is to ensure that personnel are not susceptible to injury from overheated components during normal operation of the equipment, and that high temperature conditions that can cause fire or other hazards do not occur. This chapter also includes various other hazards that should be avoided by the design of the equipment. Where no test is provided, inspection should be carried out by visual inspection, and functional tests should be used where appropriate. 6.1 High temperature
6.1.1 Allowable temperature rise under normal working conditions 471
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