Some standard content:
National Standard of the People's Republic of China
Extra-low voltage (ELV)
Extra-low voltage (ELV)--Limit values This standard is equivalent to IEC1201 "Extra-low voltage (ELV) limit values". 1 Subject content and scope of application
GB/T 3805-93
Replaces G33805--83
This standard specifies various limits of extra-low voltage to guide the correct selection and application of voltage limits related to electric shock protection. This standard applies to electrical facilities (or part of facilities) and electrical equipment involving extra-low voltage. This standard does not include voltage limits in the case of human contact with conductive parts during medical treatment. After considering some important factors and having experience that a reasonable safety level can be achieved, each professional standardization technical committee can specify the limits of extra-low voltage suitable for this profession. The factors to be considered when specifying voltage limits are shown in Appendix A. 2 Reference Standards
GB12113 Measurement of Touch Current and Ground Wire Current 3 Terminology
Grippable part refers to a part that is impossible for a person to get rid of if the current it conducts is strong enough to cause muscle contraction in the hand holding it.
Note: A part that can be gripped by the whole hand can be identified as a "gripable part" without further verification. For verification methods, see GB12113. 4 Overview
The voltage limits specified in this standard refer to the highest voltage allowed to exist between two conductive parts that can be touched at the same time under the most unfavorable conditions (all external factors that should be considered, such as the tolerance of the power grid voltage, etc.). It can be considered that the voltage within the limits specified in this standard will not be dangerous to people under the corresponding conditions. This standard gives the voltage limits in both normal (no fault) and fault states. These limits do not distinguish between grounded and ungrounded circuits. The voltages defined in this standard refer to the voltages provided by a power source whose internal impedance is much lower than the impedance of the human body. For high impedance power supply, "contact current limit" needs to be adopted. This standard does not involve data in this regard. When selecting the nominal value or rated value of the extra-low voltage involved in electrical facilities or electrical equipment, its value should be less than the corresponding limit specified in this standard, and a margin should be left. This margin should be sufficient to ensure that under various conditions and various external factors, the voltage between any two conductive parts of the electrical facilities or electrical equipment that can be touched by the human body at the same time will not exceed the corresponding limit. 5 Environmental conditions
The influence of various environmental conditions considered in this standard is: Environmental condition 1: skin impedance and ground resistance are negligible (for example, the human body is immersed in water); Environmental condition 2: skin impedance and ground resistance are reduced (for example, humid environment); State Technical Supervision Bureau approved on July 31, 1993 and implemented on February 1, 1994
GB/T3805-93
Environmental condition 3: skin impedance and ground resistance are not reduced (for example, dry environment); Environmental condition 4: special conditions (such as welding, electroplating, etc.). The impact of special conditions is defined by the relevant professional standardization technical committees.
6 Voltage Limits
The voltage limits specified in this standard have a margin for contact areas not greater than 80cm2. For small contact areas, this standard gives higher values for 15~~100Hz AC, but there is no available data for AC and DC greater than 100Hz. The voltage limits for AC are all root mean square values (rms), and are for sine waves. Other waveforms are yet to be studied. The voltage limits for DC are for ripple-free DC. DC with a sine ripple content of no more than 10% is usually called "ripple-free DC." For example: for a 120V ripple-free DC system, its peak value does not exceed 137V. 6.1 Steady-state limits
The limits for steady-state DC voltage and steady-state AC voltage for the frequency range 15 to 100 Hz for ambient conditions 1 to 3 for normal (no fault) and fault conditions are given in Table 1. For non-gripable parts with a contact area less than 1 cm2, the higher voltage limit for AC is given for ambient condition 3.
Table 11 Steady-state voltage limits for AC and DC (ripple-free) for 15 to 100 Hz Voltage limits, V
Normal conditions
Environmental conditions
(no fault)
"Single fault"
Special application
Fault conditions
"Two faults"
Notes: 1) "Single fault" means a single fault that can affect the voltage between two simultaneously accessible conductive parts. AC
(not used)
(not used)
2) "Two faults" means: two faults that exist simultaneously and can affect the voltage between two conductive parts that can be touched at the same time; if any of the faults occurs alone, that is, it has affected the voltage between the conductive parts that can be touched at the same time, it should be evaluated as a "single fault" first. 3) For grippable parts with a contact area of less than 1cm, the limit value is allowed to increase to 66V. 4) For non-grippable parts with a contact area of less than 1cm2, the limit value is allowed to increase to 80V. 5) When the battery is charging, the limit value is allowed to increase to 75V. 6) When the battery is charging, the limit value is allowed to increase to 150V. 7) The limit value is determined by the relevant professional standardization technical committee. 6.2 Voltage limit after a single fault occurs (15-100Hz AC and ripple-free DC) The voltage limit after a single fault occurs is related to the duration of the fault. The values specified in Table 1 apply to durations of 10s and above; data for durations below 10ms are yet to be studied; voltage limits for durations between 10ms and 10s are given in the curve of Figure 1 (the DC voltage limit for environmental condition 2 is yet to be studied). For conductive parts that are easily touched by the human body during normal operation, each professional standardization technical committee should consider specifying lower values. 14
（A）
6.3 Limit of single pulse
GB/T3805--93
A: Environmental condition 3 (dc)
B: Environmental condition 3 (acicmt)
C: Environmental condition 3 (a.
D: Environmental condition 2 (ac)
Water-induced voltage
Time (ms)
Figure 1 Voltage limits of AC (15-100Hz) and DC after a single fault occurs 10000
When the duration after a single fault occurs is not less than 10ms, the limit of a unidirectional single pulse can apply the DC curve in Figure 1. The limit of a duration shorter than 10ms To be studied. 6.4 Limits above 100 Hz
For AC with a frequency higher than 100 Hz, the limits for environmental conditions 2 and 3 under normal conditions are given in the curve of Figure 2. When the frequency is above 1 kHz, the limits for environmental conditions 2 and 3 are the same. The maximum voltage in the frequency range of 1 to 5 kHz is 10 V. For AC with a frequency higher than 100 Hz, the limits for environmental conditions 2 and 3 under single fault conditions are given in the curve of Figure 3. When the frequency is above 50 kHz, the limits for environmental conditions 2 and 3 are the same. For AC with a frequency higher than 50 kHz, the maximum voltage taking into account the burning effect is 50 V in both normal and single fault conditions,
GB/T 3805-
a: Environmental condition 2 (ac)
b: Environmental condition 3 (ac
100000
Frequency (Hz)
Figure 2 Voltage limit considering frequency effect under normal (no fault) state (A)
Group: Environmental condition 2 (ac
b: Environmental condition 3 (ac)
GB/T3805--93
Figure 3 Voltage limit considering frequency effect under single fault state 6.5 Limit values of charged capacitors
100000
Frequency (H2)
The curve in Figure 4 gives the voltage limits on charged capacitors of various capacitances that may discharge into the human body. The voltage values of the cut-off lines marked with A, BC and D on the right side of Figure 4 correspond to the DC steady-state voltage limits under the corresponding conditions in Table 1. 17
10) u00
35 F -
Pain treatment
No cardiac fibrillation·—-
GB/T 3805—93
A: Environmental condition 3 single fault
B: Environmental condition 2 (single fault)
C: Environmental condition 3 (unexplained drop)
D: Environmental condition 2 (no fault)
Figure 4 Voltage and capacitance limits of capacitors that may discharge to the human body 100
Capacitance ()
Table 2 expresses the pain threshold curve (see curve a in Figure 4). Each professional standardization technical committee may specify the limit values suitable for the needs of this profession based on the discharge method, possibility of contact and other specific conditions, on the premise of ensuring personal safety. 18
GB/T 3805--93
Table 2 Capacitance limit value based on pain valve Capacitance
20 000
Capacitance
For voltages below 70V, when used in a non-fault state with environmental condition 3, the capacitance limit value based on pain of the capacitor may not be limited (see cut-off line C in Figure 4), but when used in a non-fault state with environmental condition 2, the limit value based on absence of cardiac fibrillation needs to be considered. For voltages below 35V, when used in a non-fault state with environmental condition 2, the capacitance may not be limited (see cut-off line C in Figure 4). Line D).
The curve b in Figure 4 expresses the limit value based on the absence of cardiac fibrillation. It is generally used in a single fault state (in a fault-free state, when the environmental condition is 2, the voltage range of 35 to 70V still needs to be applied to this curve). When the capacitance of the capacitor has been determined and its voltage limit needs to be calculated, the following formula can be used: U
Where: U--voltage, V;
C capacitance.μF.
(13. 38 × 1037354
（1）
When the calculated voltage limit is lower than the DC voltage limit under the corresponding conditions in Table 1, the voltage limit of the capacitance can be required according to the limit in Table 1.
When the voltage limit across the capacitor has been determined and the capacitance limit needs to be calculated, the following formula can be used: C13.38×109×-1.354
Where: C-capacitance μF;
U---voltage, V. ||t Table 3 lists some data calculated by formula (2). (2) GB/T 3805 Table 3 Capacitance limit based on no cardiac fibrillation Capacitance Capacitance When the voltage across the capacitor is limited to be lower than the DC voltage limit under the corresponding conditions in Table 1, the capacitance limit may not be limited by formula (2) and Table 3 (see cut-off lines A, B and D in Figure 4). 20 GB/T 3805 5—93 Appendix A Factors affecting voltage limit (reference) Factors marked with "*" have been considered in the preparation of this standard and have affected the determination of voltage limit in this standard. When specifying the corresponding voltage limits, each professional standardization technical committee should consider the following factors: A1 Human body impedance
*Contact voltage;
*Skin moisture level;
Current path:
*Contact area;
Contact pressure;
*Waveform and frequency of the current flowing through the human body. A2
Touchable parts
*Contact area (fingertips, fingers, hands);*Possibility of being gripped;
Location of touchable parts;
Intentional touch/unintentional touch.
A3 Electrical system
*AC/DC;
*Waveform, frequency, single pulse;
*Reference ground/floating ground;
Isolation from other systems;
Power supply impedance;
Circuit breaking device;
*Nominal value/maximum value, tolerance.
External influences
Humidity;
Temperature, dust;
Conductivity;
Secondary reaction;
Direct contact/indirect contact;
Clothing.
5 People's competences
Professionals/trained people/ordinary people, children;
Disabled people.
Boundaries divided by the following physiological effects:
*Perception;
*Reaction;
*Pain;
*Burn;
|*Get rid of;
*Paralysis;
*Fibrillation of the heart.
Boundaries are divided by the following electrical parameters:
GB/T3805-93
*Voltage (AC/DC, RMS value; peak value; waveform);*Current (AC/DC, RMS value);*Energy,
*Charge;
*Frequency.
When studying the limits related to electrical parameters, the measurement method must be taken into account because it affects the selection of values. Additional notes:
This standard was proposed by the Ministry of Labor of the People's Republic of China. This standard is technically coordinated by the National Electrical Safety Standardization Technical Committee. This standard was drafted by the Beijing Labor Protection Science Research Institute. The main drafters of this standard are Zhu Deji and Liu Xiuzhen. 22(2)
GB/T3805
Table 3 Capacitance limit based on no cardiac fibrillation Capacitance
Capacitance
When the voltage across the capacitor is limited to be lower than the DC voltage limit under the corresponding conditions in Table 1, its capacitance limit may not be limited by formula (2) and Table 3 (see cut-off lines A, B and D in Figure 4). 20
GB/T 3805
5-93
Appendix A
Factors affecting voltage limit
(reference)
Factors marked with "*" have been taken into consideration when compiling this standard and have affected the determination of voltage limit in this standard. When specifying the corresponding voltage limits, each professional standardization technical committee should consider the following factors: A1 Human body impedance
*Contact voltage;
*Skin moisture level;
Current path:
*Contact area;
Contact pressure;
*Waveform and frequency of the current flowing through the human body. A2
Touchable parts
*Contact area (fingertips, fingers, hands);*Possibility of being gripped;
Location of touchable parts;
Intentional touch/unintentional touch.
A3 Electrical system
*AC/DC;
*Waveform, frequency, single pulse;
*Reference ground/floating ground;
Isolation from other systems;
Power supply impedance;
Circuit breaking device;
*Nominal value/maximum value, tolerance.
External influences
Humidity;
Temperature, dust;
Conductivity;
Secondary reaction;
Direct contact/indirect contact;
Clothing.
5 People's competenceswww.bzxz.net
Professionals/trained people/ordinary people, children;
Disabled people.
Boundaries divided by the following physiological effects:
*Perception;
*Reaction;
*Pain;
*Burn;
|*Get rid of;
*Paralysis;
*Fibrillation of the heart.
Boundaries are divided by the following electrical parameters:
GB/T3805-93
*Voltage (AC/DC, RMS value; peak value; waveform);*Current (AC/DC, RMS value);*Energy,
*Charge;
*Frequency.
When studying the limits related to electrical parameters, the measurement method must be taken into account because it affects the selection of values. Additional notes:
This standard was proposed by the Ministry of Labor of the People's Republic of China. This standard is technically coordinated by the National Electrical Safety Standardization Technical Committee. This standard was drafted by the Beijing Labor Protection Science Research Institute. The main drafters of this standard are Zhu Deji and Liu Xiuzhen. 22(2)
GB/T3805
Table 3 Capacitance limit based on no cardiac fibrillation Capacitance
Capacitance
When the voltage across the capacitor is limited to be lower than the DC voltage limit under the corresponding conditions in Table 1, its capacitance limit may not be limited by formula (2) and Table 3 (see cut-off lines A, B and D in Figure 4). 20
GB/T 3805
5-93
Appendix A
Factors affecting voltage limit
(reference)
Factors marked with "*" have been taken into consideration when compiling this standard and have affected the determination of voltage limit in this standard. When specifying the corresponding voltage limits, each professional standardization technical committee should consider the following factors: A1 Human body impedance
*Contact voltage;
*Skin moisture level;
Current path:
*Contact area;
Contact pressure;
*Waveform and frequency of the current flowing through the human body. A2
Touchable parts
*Contact area (fingertips, fingers, hands);*Possibility of being gripped;
Location of touchable parts;
Intentional touch/unintentional touch.
A3 Electrical system
*AC/DC;
*Waveform, frequency, single pulse;
*Reference ground/floating ground;
Isolation from other systems;
Power supply impedance;
Circuit breaking device;
*Nominal value/maximum value, tolerance.
External influences
Humidity;
Temperature, dust;
Conductivity;
Secondary reaction;
Direct contact/indirect contact;
Clothing.
5 People's competences
Professionals/trained people/ordinary people, children;
Disabled people.
Boundaries divided by the following physiological effects:
*Perception;
*Reaction;
*Pain;
*Burn;
|*Get rid of;
*Paralysis;
*Fibrillation of the heart.
Boundaries are divided by the following electrical parameters:
GB/T3805-93
*Voltage (AC/DC, RMS value; peak value; waveform);*Current (AC/DC, RMS value);*Energy,
*Charge;
*Frequency.
When studying the limits related to electrical parameters, the measurement method must be taken into account because it affects the selection of values. Additional notes:
This standard was proposed by the Ministry of Labor of the People's Republic of China. This standard is technically coordinated by the National Electrical Safety Standardization Technical Committee. This standard was drafted by the Beijing Labor Protection Science Research Institute. The main drafters of this standard are Zhu Deji and Liu Xiuzhen. 22
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