A circuit structure that electrically isolates the input, output, and power supply from each other is used, while meeting the intrinsic safety requirement to limit energy. Compared with Zener security, although its price is slightly higher, its outstanding advantages in other aspects have brought greater benefits to user applications:
1. Since the three-way isolation method is adopted, no system grounding line is required, which brings great convenience to design and site construction.
2. The instrument requirements for hazardous areas are greatly reduced, and there is no need to use isolated instruments on site.
3. Since the signal lines do not need common ground, the stability and anti-interference ability of the detection and control loop signals are greatly enhanced, thereby improving the reliability of the entire system.
4. Isolated barriers have stronger input signal processing capabilities and are capable of accepting and processing signals such as thermocouples, thermal resistors, and frequencies, which Zener barriers cannot.
5. Isolated barriers can output two mutually isolated signals to be used by two devices that use the same signal source, and ensure that the signals of the two devices do not interfere with each other, and at the same time improve the electrical safety insulation performance of the connected devices. .
Therefore, after comparing the characteristics and performance of the Zener-type and isolated safety barriers, it can be seen that the isolated safety barrier has outstanding advantages and is more widely used. Although its price is slightly higher than that of the Zener-type safety barrier, it is designed, Considering the cost of construction installation, commissioning and maintenance, the overall cost may be lower than the Zener barrier. In the more demanding engineering field, almost without exception, the isolated safety barrier is used as the main intrinsically safe explosion-proof instrument. The isolated safety barrier has gradually replaced the Zener safety barrier and has been increasingly widely used in the field of safety and explosion protection.
Intrinsically Safe Device Mark Definitions: Ex - Explosion Proof Mark (ia) - Explosion-proof Class IIC - Gas Group Explosion Proof Level of the Company's Products: Ex (ia) IIC
Explosion-proof level ia: Under normal operating conditions, no hazardous gas will be ignited in 1 fault or 2 fault states. The circuit must ensure that the safety features are still guaranteed when both faults occur. "IA" electrical equipment must be "triple" in design for components that are susceptible to interference. The "ib" type electrical equipment can only ensure that no dangerous gas will be ignited in a fault condition.
Gas Group I Electrical Equipment: Used in mine environments susceptible to methane.
Group II electrical equipment: Can be used in explosion hazardous environments other than coal mines.
Group II electrical equipment is further subdivided based on the ignition energy of different flammable substances.
Each subgroup is distinguished by uppercase and lowercase English letters. From the following table, it can be seen that the ignition energy required for subgroup C is the least. That is, in the group of electric devices, the group C equipment is universal.
The areas of common explosion flammable substances are classified into the design of safety explosion-proof systems and the selection of explosion-proof products. Apart from the need to classify and classify the gases present in explosive atmospheres, they should also be based on the frequent occurrence of explosive gases. Degree and duration Regional division of explosive gas hazardous locations: The company's products are applicable to Zone 0, while Zones 1 and 2 are applicable.
The yellow end (non-intrinsically safe side) of the color code leads to the safe area.
The use of the blue end (intrinsically safe) wiring to the hazardous area barrier 1. Isolated barriers should be installed in non-hazardous locations.
2. The cross-sectional area of ​​the soft copper conductor to the site (hazardous area) of the isolated barrier must be greater than 0.5 mm2.
3. The insulation strength of the connecting wire is greater than 500V.
4. Isolated safety barrier intrinsically safe (with blue mark) and non-intrinsically safe end circuit wiring shall not be connected incorrectly or confused. Intrinsically safe conductors should use blue as an intrinsically safe marker. Intrinsically safe conductors and non-intrinsically safe conductors shall be laid separately in the trunking troughs and their respective protective sleeves shall be used. The intrinsically safe side of an isolated barrier must not be confused with other sources of power, including other intrinsically safe circuits.
5. When an isolating safety barrier and a meter compose an intrinsically safe explosion-proof system, they must be inspected and approved by a state-specified explosion-proof inspection agency. The WP8000-EX series isolated safety barrier is provided by the national explosion-proof electrical supervision and inspection center. The distribution parameters of Co and Lo given are relative to the maximum allowable value of class IIC (hydrogen gas). For the class IIB environment, this parameter can be multiplied by 3, for The IIA environment can multiply this parameter by 8. When using different cable sizes for transmission lines, their own cable parameters should be highly valued and must not exceed the specified values.
6. When isolated power grids are commissioned separately, attention must be paid to the type of isolated barrier, the polarity of the power supply, the voltage level, and the marking on the terminals of the isolated barrier enclosure.
7. Do not use megohmmeters to test the insulation between the isolated barrier terminals. To check the insulation of the system wiring, disconnect all the isolated safety barrier wiring first, otherwise it will cause internal device damage.
8. All field instruments connected to the isolation barrier shall be explosion-proof tests performed by the relevant explosion-proof department and shall be certified by the explosion-proof certificate.
9. When the internal module of the isolated barrier needs to be repaired or replaced, it should be borne by the manufacturer in principle. When users perform maintenance on their own, they should follow the relevant precautions. The specific methods should be followed in accordance with the maintenance section. (Intrinsically safe instrument maintenance is limited to the above-mentioned scope, and the external maintenance should be commensurate with the manufacturer's specifications). After being overhauled, it can be put back into operation.
10. The installation, use and maintenance of isolated safety barriers shall strictly comply with the relevant provisions of GB 3836.15-2000 "Electrical Equipment for Explosive Gas Environments Part 15: Electrical installations in hazardous locations (except coal mines)".
11. Products that have obtained the explosion-proof certificate do not allow to replace the components that affect the explosion-proof performance or the precautions in the installation of the structure. 1. The safety fence should be installed in a safe place and the environmental conditions can meet the “use conditions†in the “General Specifications†of this manual. "The request.
2. The wiring of the intrinsically safe end (blue mark) and the non-intrinsically safe end of the isolation barrier shall be laid separately in the trunking and separate protective sleeves shall be used. No other power cords, including the power cords used in their intrinsically safe circuits, are allowed inside the wiring harness on the intrinsically safe side.
3. The wire leading to the dangerous place should use the blue mark of the intrinsically safe wire. The soft copper area of ​​the wire must be greater than 0.5mm2, and the insulation strength should be greater than 500V.
4. Before energizing and debugging the isolated safety barrier, it is necessary to pay attention to the model, wiring method, line polarity, etc. of the isolated safety barrier. Whether it meets the requirements in the design and product requirements, otherwise it may cause harm to people and equipment.
5. Never use megohmmeters to test the insulation strength between isolated barrier terminals. If you want to check the insulation strength of the system, you should disconnect all the wiring first, otherwise it may cause the quick-break fuse inside the safety fence to break.
6. Before programming the safety barrier in the field, you must first disconnect all the wires and then connect it to the programmer, and then energize the programming, otherwise it may cause adverse consequences.
7. The on-site instruments connected to the isolated safety barrier shall pass the explosion-proof test of the explosion-proof inspection department certified by the state and obtain the explosion-proof certificate.
8. When designing, installing, using, and maintaining isolated barriers, obey the instructions in this product manual and “GB3836.15-2000 Electrical Equipment for Explosive Gas Environments Part XV: Electrical installation in hazardous locations (except coal mines) ), "GB50058-1992 Explosion and Fire Hazard Environment Power Design Specification."
1. Since the three-way isolation method is adopted, no system grounding line is required, which brings great convenience to design and site construction.
2. The instrument requirements for hazardous areas are greatly reduced, and there is no need to use isolated instruments on site.
3. Since the signal lines do not need common ground, the stability and anti-interference ability of the detection and control loop signals are greatly enhanced, thereby improving the reliability of the entire system.
4. Isolated barriers have stronger input signal processing capabilities and are capable of accepting and processing signals such as thermocouples, thermal resistors, and frequencies, which Zener barriers cannot.
5. Isolated barriers can output two mutually isolated signals to be used by two devices that use the same signal source, and ensure that the signals of the two devices do not interfere with each other, and at the same time improve the electrical safety insulation performance of the connected devices. .
Therefore, after comparing the characteristics and performance of the Zener-type and isolated safety barriers, it can be seen that the isolated safety barrier has outstanding advantages and is more widely used. Although its price is slightly higher than that of the Zener-type safety barrier, it is designed, Considering the cost of construction installation, commissioning and maintenance, the overall cost may be lower than the Zener barrier. In the more demanding engineering field, almost without exception, the isolated safety barrier is used as the main intrinsically safe explosion-proof instrument. The isolated safety barrier has gradually replaced the Zener safety barrier and has been increasingly widely used in the field of safety and explosion protection.
Intrinsically Safe Device Mark Definitions: Ex - Explosion Proof Mark (ia) - Explosion-proof Class IIC - Gas Group Explosion Proof Level of the Company's Products: Ex (ia) IIC
Explosion-proof level ia: Under normal operating conditions, no hazardous gas will be ignited in 1 fault or 2 fault states. The circuit must ensure that the safety features are still guaranteed when both faults occur. "IA" electrical equipment must be "triple" in design for components that are susceptible to interference. The "ib" type electrical equipment can only ensure that no dangerous gas will be ignited in a fault condition.
Gas Group I Electrical Equipment: Used in mine environments susceptible to methane.
Group II electrical equipment: Can be used in explosion hazardous environments other than coal mines.
Group II electrical equipment is further subdivided based on the ignition energy of different flammable substances.
Each subgroup is distinguished by uppercase and lowercase English letters. From the following table, it can be seen that the ignition energy required for subgroup C is the least. That is, in the group of electric devices, the group C equipment is universal.
The areas of common explosion flammable substances are classified into the design of safety explosion-proof systems and the selection of explosion-proof products. Apart from the need to classify and classify the gases present in explosive atmospheres, they should also be based on the frequent occurrence of explosive gases. Degree and duration Regional division of explosive gas hazardous locations: The company's products are applicable to Zone 0, while Zones 1 and 2 are applicable.
The yellow end (non-intrinsically safe side) of the color code leads to the safe area.
The use of the blue end (intrinsically safe) wiring to the hazardous area barrier 1. Isolated barriers should be installed in non-hazardous locations.
2. The cross-sectional area of ​​the soft copper conductor to the site (hazardous area) of the isolated barrier must be greater than 0.5 mm2.
3. The insulation strength of the connecting wire is greater than 500V.
4. Isolated safety barrier intrinsically safe (with blue mark) and non-intrinsically safe end circuit wiring shall not be connected incorrectly or confused. Intrinsically safe conductors should use blue as an intrinsically safe marker. Intrinsically safe conductors and non-intrinsically safe conductors shall be laid separately in the trunking troughs and their respective protective sleeves shall be used. The intrinsically safe side of an isolated barrier must not be confused with other sources of power, including other intrinsically safe circuits.
5. When an isolating safety barrier and a meter compose an intrinsically safe explosion-proof system, they must be inspected and approved by a state-specified explosion-proof inspection agency. The WP8000-EX series isolated safety barrier is provided by the national explosion-proof electrical supervision and inspection center. The distribution parameters of Co and Lo given are relative to the maximum allowable value of class IIC (hydrogen gas). For the class IIB environment, this parameter can be multiplied by 3, for The IIA environment can multiply this parameter by 8. When using different cable sizes for transmission lines, their own cable parameters should be highly valued and must not exceed the specified values.
6. When isolated power grids are commissioned separately, attention must be paid to the type of isolated barrier, the polarity of the power supply, the voltage level, and the marking on the terminals of the isolated barrier enclosure.
7. Do not use megohmmeters to test the insulation between the isolated barrier terminals. To check the insulation of the system wiring, disconnect all the isolated safety barrier wiring first, otherwise it will cause internal device damage.
8. All field instruments connected to the isolation barrier shall be explosion-proof tests performed by the relevant explosion-proof department and shall be certified by the explosion-proof certificate.
9. When the internal module of the isolated barrier needs to be repaired or replaced, it should be borne by the manufacturer in principle. When users perform maintenance on their own, they should follow the relevant precautions. The specific methods should be followed in accordance with the maintenance section. (Intrinsically safe instrument maintenance is limited to the above-mentioned scope, and the external maintenance should be commensurate with the manufacturer's specifications). After being overhauled, it can be put back into operation.
10. The installation, use and maintenance of isolated safety barriers shall strictly comply with the relevant provisions of GB 3836.15-2000 "Electrical Equipment for Explosive Gas Environments Part 15: Electrical installations in hazardous locations (except coal mines)".
11. Products that have obtained the explosion-proof certificate do not allow to replace the components that affect the explosion-proof performance or the precautions in the installation of the structure. 1. The safety fence should be installed in a safe place and the environmental conditions can meet the “use conditions†in the “General Specifications†of this manual. "The request.
2. The wiring of the intrinsically safe end (blue mark) and the non-intrinsically safe end of the isolation barrier shall be laid separately in the trunking and separate protective sleeves shall be used. No other power cords, including the power cords used in their intrinsically safe circuits, are allowed inside the wiring harness on the intrinsically safe side.
3. The wire leading to the dangerous place should use the blue mark of the intrinsically safe wire. The soft copper area of ​​the wire must be greater than 0.5mm2, and the insulation strength should be greater than 500V.
4. Before energizing and debugging the isolated safety barrier, it is necessary to pay attention to the model, wiring method, line polarity, etc. of the isolated safety barrier. Whether it meets the requirements in the design and product requirements, otherwise it may cause harm to people and equipment.
5. Never use megohmmeters to test the insulation strength between isolated barrier terminals. If you want to check the insulation strength of the system, you should disconnect all the wiring first, otherwise it may cause the quick-break fuse inside the safety fence to break.
6. Before programming the safety barrier in the field, you must first disconnect all the wires and then connect it to the programmer, and then energize the programming, otherwise it may cause adverse consequences.
7. The on-site instruments connected to the isolated safety barrier shall pass the explosion-proof test of the explosion-proof inspection department certified by the state and obtain the explosion-proof certificate.
8. When designing, installing, using, and maintaining isolated barriers, obey the instructions in this product manual and “GB3836.15-2000 Electrical Equipment for Explosive Gas Environments Part XV: Electrical installation in hazardous locations (except coal mines) ), "GB50058-1992 Explosion and Fire Hazard Environment Power Design Specification."
Chongqing Taishan Cable Co., Ltd. , http://www.cqbareconductor.com