HG/T 20540-1992 Technical regulations for power design of fertilizer plants
Some standard content:
Industry Standard of the People's Republic of China
HC 2054092
Technical Regulations for the Design of Fertilizer and Electric Power
199302 No. 04 Issued
19930301 Implementation
Issued by the Ministry of Chemical Industry of the People's Republic of ChinaATATTAT
Industry Standard of the People's Republic of China
Technical Regulations for the Design of Fertilizer and Electric Power
HG 20540-92
Editor: Fourth Design Institute of Ministry of Chemical Industry
Approval Department: Ministry of Chemical Industry
Implementation Date: March 1, 1993
Engineering Construction Standard Editing Center of Ministry of Chemical Industry
1993 Beijing
General Principles
Determination of Power Supply Scheme
Power Supply and Distribution System,
3.1 Power Supply and Main Connection
3.2 Low Voltage Distribution System
3.3 Voltage Level
Reactive Power Compensation
Communication System
Electrical Load Calculation.
Short Circuit Current Calculation
Subject List
110kV and below Electrical Equipment Technology Parameter selection relay protection and automatic devices
7.1 General provisions
7.2 Protection of power equipment and lines
7.3 Automatic devices
Secondary circuits and operating power supply
8.1 Control and signal circuits
8.2 Electrical measurement and energy metering
8.3 Central signaling device
8.4 Protection of secondary circuits and equipment selection
8.5 Control protection and signaling panel
8.6 Secondary circuit wiring
8.7 Operating power supply
Electrical layout
9.16110kV substation and distribution station
（16)
·(26)
·(36)
（(41)
- (43)
9.2 Workshop transformer and distribution station
9.3 Electric filter rectifier
9.4 Requirements for civil engineering
10 Environmental characteristics and measures
[0.1 Main content and purpose
.10.2 Gas or steam explosion hazardous environment
10.3 Dust explosion hazardous environment
1.0.4 Fire hazardous environment
10.5 Corrosive environment
10.6 Selection of electrical equipment in explosion and fire hazardous environments and corrosive environments10.7 General environmental characteristics of the main production equipment of fertilizer plants and overhead lines11
|Selection and laying of cables and conductors
11.1 Selection of cables and conductors
11.2 Cable laying in factory areas
11.3 Laying of distribution lines in workshops
12. Control, protection and self-starting of low-voltage power equipment in workshops 12.1 Control and protection of low-voltage power equipment in workshops 12.2 Self-starting of electrical equipment
13 Overvoltage protection
13.1 Internal overvoltage and its protection
13.2 Lightning protection for buildings and structures
13.3 Protection against overvoltage outside substations and distribution stations 13.4 Overvoltage protection device
14 Grounding and zeroing!
Appendix A
Explanation of terms used in this Regulation
Explanation of clauses
.{(71)
· (102)
·{106
(118)
This Regulation is formulated in accordance with the national design specifications and relevant standards of the Ministry of Chemical Industry and with reference to the design technical regulations of relevant ministries.
This Regulation applies to the power design of newly built, rebuilt or expanded fertilizer plants. 1.0.2
In addition to implementing this Regulation, the power design of fertilizer plants shall also comply with the provisions of the current national1.03
relevant standards and implement relevant national directive documents. 2 Determination of power supply plan
2.0.L Before determining the power supply plan, investigation, research and data preparation should be done well. 2.0.1.1 Fully study and analyze the load situation, reasonably determine the load level and quantity, and master its characteristics and requirements.
Understand the power supply situation: including the system connection of the regional power grid, the scale and long-term development of the regional substation 2.0.1.2
, the possible voltage level and number of circuits for power supply, short-circuit data of various system operation modes, system grounding requirements, line protection methods and coordination, etc. 2.0.1.3 Collect regional meteorological data and geological data for the selection of electrical equipment and design calculations: collect information and calculation methods on electricity prices, subsidies and other costs: specific regulations and requirements for electric energy metering: collect relevant rules and regulations of local power departments on power design requirements.
2.0.1.4 During the project proposal and feasibility study design stage, the local power supply department should be contacted and a principled agreement should be reached on power supply reliability, power consumption capacity, thermal engine networking and power supply conditions (or plans).
2.0.2 During the preliminary design stage of the engineering design, the power supply plan should be determined through consultation with the power supply department, and the construction unit and the power supply department should sign a power supply agreement. As the basis for design.
According to the provisions on load classification in the national standard "Design Specifications for Industrial and Civil Power Supply Systems" (GBJ52-83), the load of the fertilizer plant production equipment should be classified as a secondary load.
The load that must be kept powered on to ensure safe parking or to facilitate timely handling to prevent the expansion of the fault, rescue and evacuation of personnel, etc. when the power supply is suddenly interrupted should be classified as a security load. For the security load in the production equipment, measures should be taken inside the factory to ensure power supply.
2.0.4 When designing the power supply and distribution system, several different schemes should be proposed for comprehensive technical and economic comparison, and a reasonable scheme should be selected from them to ensure safety, reliability, advanced technology and economic rationality.
The contents of technical comparison can be considered as follows: 2.0.5.1
Reliability and flexibility of power supply:
Power supply quality;
Technological advancement of main equipment and materials: Construction conditions and construction progress:
Adaptation to short-term needs and long-term development as well as the possibility of transitional power supply during renovation and expansion The contents of economic comparison can be considered as follows 2.0.6.1
Investment;
Annual operating expenses;
Electric energy loss;
Non-ferrous metal consumption:
Area of land;
Payback period.
The selection of the scheme can be based on the following principles
Fully reflect the technical policies and energy-saving principles of the state in economic construction: comply with relevant national regulations and meet the requirements of major technical conditions: technically superior and economically reasonable
3
Power supply and distribution system
Power supply and main connection
3.1.1 The fertilizer plant should be powered by two power lines. If it is difficult to obtain a double-circuit power line, a one-to-one dedicated line can also be used for power supply. 3.1.2. In order to meet the power supply requirements of the security load, a security power supply device independent of the power system should be set up, such as an uninterruptible power supply device, a battery, a fast-starting emergency generator set, etc.
When the factory has a self-contained power station, it should be determined whether it can be used as an independent working power supply based on the load size, the type, capacity and operation mode of the steam turbine generator set. Generally, it can be used as an auxiliary power supply. 3.1.3 When there is a security load, an independent security power supply system should be set up. In some substations, a dedicated security power bus section is set up. When the working power is cut off, the security load can be quickly switched to the security power system.
3.1.4 When there are two normal production power lines and they work at the same time and serve as backup for each other, the transmission capacity of the line should be able to meet the requirement that when one of the lines is cut off, the remaining lines can still guarantee the power supply to all production loads. 3.15 When designing the power lines of the power supply and distribution system, it is not considered that when one power line is under maintenance or failure, the other power line will fail. 3.1.6 According to the external power supply conditions, the needs of the power load and the requirements for power supply reliability, a total step-down substation or a total distribution station is set up. 3.1.7 The capacity and number of the main transformers of the total step-down substation should be determined according to the power supply conditions, the size of the power load and the development of the factory. When there are two main transformers, the capacity of the transformer should meet the requirement that when one of them is disconnected, the other can carry 70% to 100% of the total production load. 4
3.1.8 The capacity of the steam turbine generator set of the self-contained power station should be determined according to the principle of "steam determines electricity". 3.1.9 The main connection of the main step-down substation or main distribution station should be determined in consultation with the power department. The connection should be simple and flexible and meet the requirements of operation, maintenance, relay protection and automatic devices.
The 6~10kV busbar of the main step-down substation or main distribution station should adopt a single busbar or a single busbar segmented connection, and the electrical equipment of the same production system should be connected to the same section of the busbar. 3.1.10 In a total step-down substation with a larger capacity, when it is necessary to limit the short-circuit current on the -6~10kV outgoing line, the transformer split operation should be given priority in the design. The second is to install a current limiting reactor or a split reactor in the transformer circuit. When the installation of a total current limiting reactor cannot meet the requirements or the technical and economic conditions are relatively reasonable, a current limiting reactor can be installed on the 6~10kV outgoing line.
3.1.11 In a 6~10kV network, when the single-phase grounding capacitance current is greater than 30A, there should be grounding compensation measures in the network. 3.1.12 The high-voltage distribution voltage in the plant area should be 6kV or 10kV after technical and economic comparison based on the capacity and number of high-voltage motors and the capacity and number of transformers. The whole plant should adopt a high-voltage distribution voltage, and two types can also be used in special cases.
The 610kV distribution in the production unit area should adopt a radial system. 3.1.13
The level of 6~10kV power distribution should not exceed two levels. 3.1.14 The location of the main step-down substation or main distribution station shall meet the following requirements 3.1.14.1 The location on the general layout plan of the factory should be on the upwind side of the corrosive gas, dust device and cooling tower (corrosive gas and dust refer to the upwind side of the dominant wind direction in summer or the leeward side of the minimum wind frequency, and the dominant wind direction in winter for cooling towers).
The distance from the explosion hazard and corrosion environment of the chemical production equipment should meet the requirements of Table 3.1.14.2.
The access line is convenient, and the 35~110kV overhead line can be led to the power receiving device without passing through the production equipment area!
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3.11.14.6
Convenient for the transportation of main equipment
As close to the load center as possible under the above conditions. It should be an independent building with the conditions for expansion as needed. Main step-down substation or main distribution station
Distance requirements from certain environments
Explosion-hazardous environment
Medium-corrosive environment
Strongly corrosive environment
Fire-hazardous places
Table 3.1.14.2
Refers to explosion-hazardous devices
and buildings
6~10kV secondary distribution stations should not be connected to explosion-hazardous chemical production devices: (including upstairs or downstairs), and should be set outside the explosion-hazardous area and corrosion area of the chemical production device.
3.1.16 The workshop transformer adopts the line-transformer group wiring method. No isolating switch may be installed on the high-voltage side of the workshop transformer. When the workshop substation is equipped with two transformers, its power supply line should be connected to different bus sections of 6-10 kV high-voltage distribution station.
3.1.17: When there may be power feedback in the 6-10 kV outgoing line circuit, if it is a fixed switch cabinet, an isolating switch should be installed behind the circuit breaker. 3.1.18 The main step-down substation or main distribution station should have two power supplies. A backup power automatic input device should be installed between the two power supplies. 3.1.19 When the main step-down substation or 6-10 kV high-voltage distribution station is connected to a high-voltage motor, in the humid tropical area or the environment where the high-voltage motor is located is humid and there are no moisture-proof measures, a power supply for heating and drying the high-voltage motor when it is stopped should be installed. When the drying power supply is connected by the high-voltage switch cabinet, there should be measures to lock the circuit breaker to prevent misoperation.
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3.2 Low-voltage power distribution system
The low-voltage power distribution voltage is 380/220V, and the three-phase load is connected to 380V. The single-phase load is connected to 380V or 220V.
The voltage of lighting fixtures is single-phase 220V. The maintenance lighting in special environments uses 36V or 12V.
3.2.2 In the low-voltage power distribution system with 380/220V neutral point directly grounded, the connection group of the workshop transformer should be D, yn type. 3.2.3·The workshop substation with mainly secondary loads should be equipped with two transformers: The workshop substation with mainly tertiary loads can be equipped with one transformer: However, if there are some secondary loads, low-voltage interconnection lines from different buses should be connected from other substations to meet the requirements of secondary load power supply reliability.
3.2.4 The low-voltage side of the workshop substation should adopt a single busbar or a single busbar segmented connection. The low-voltage system of the workshop substation should be compatible with the process production system, and the electrical equipment of the same production system should be powered by the same busbar. 3.2.5 Load rate of the workshop substation transformer 3.2.5.1 When two transformers are used for power supply at the same time, when one is disconnected, the other can carry 70% to 100% of the production load. www.bzxz.net
3.2.5.2 When more than two transformers are used for power supply at the same time, when one is disconnected, the remaining transformers can carry 100% of the production load. 3.2.5.3 When three transformers are selected and one of them is used as a public standby, a load rate of 80% can be considered.
When a single transformer is selected for power supply, the load rate should be less than 80%. 3.2.5.5 The transformer capacity should also be verified according to the starting and self-starting conditions of the motor.
3.2.6 The main circuit breaker and busbar section circuit breaker on the low-voltage side of the transformer generally use low-voltage circuit breakers with delayed overcurrent releases. 7
The workshop substation should be set outside the explosion-hazardous area 3.2.73
3.2.8 Lighting generally shares the power supply of the transformer with the power load. When the power supply voltage deviation often exceeds the rated value ±5%, in order to ensure the power supply quality of lighting, it is advisable to separate the power supply from the lighting, and set up a dedicated lighting transformer to form an independent lighting power supply system.
Each production device and workshop should have a maintenance power supply. A certain number of maintenance power switch boxes and sockets should be set up as needed: the power supply range can be considered as 30m, and a trunk distribution system should be adopted.
3.2.10 In a 380/220V neutral point directly grounded network, single-phase 220V loads should be distributed as evenly as possible in the three-phase line. The connection group is Y, y. For three-phase transformers of this type, the neutral current shall not exceed 25% of the rated current of the low-voltage winding. And the current of one phase shall not exceed the rated current value when fully loaded. For transformers of other connection groups, if their manufacturing standards provide otherwise, they may not be subject to this restriction. 3.3
Voltage level
3.3.1 In order to ensure the quality of power supply, according to the requirements of various electrical equipment, the following voltage deviation allowable values shall be verified during design. 3.3.1.1 Terminal voltage of motor:
(1) ±5% under normal circumstances;
(2) +5%, -10% under special circumstances.
3.3.1.2 Terminal voltage of lighting fixtures:
(I) In general workplaces
(2) In indoor places with high visual requirements (except gas discharge lamps) -2.5%;
(3) Emergency lighting, road lighting and 12~36V maintenance lighting 1+5%, -10%.
3.3.1.3 Terminal voltage of other electrical equipment: unless otherwise specified
±5%.
W.6
Convenient for transportation of main equipment
As close to the load center as possible while meeting the above conditions. It should be an independent building with the conditions for expansion as needed. Main step-down substation or main distribution station
Distance requirements from certain environments
Explosion-hazardous environment
Medium-corrosive environment
Strongly corrosive environment
Fire-hazardous places
Table 3.1.14.2
Refers to explosion-hazardous devices
and buildings
6~10kV secondary distribution stations should not be connected to explosion-hazardous chemical production equipment: (including upstairs or downstairs), and should be located outside the explosion-hazardous area and corrosion area of the chemical production equipment.
3.1.16 The workshop transformer adopts the line-to-transformer group wiring method. The isolating switch may not be installed on the high-voltage side of the workshop transformer site. When the workshop substation is equipped with two transformers, its power supply line should be connected to different bus sections of 6-10 kV high-voltage distribution station.
3.1.17: When there may be power feedback in the 6-10 kV outgoing line circuit, if it is a fixed switch cabinet, an isolating switch should be installed behind the circuit breaker. 3.1.18 The main step-down substation or main distribution station should have two power supplies. A backup power automatic input device should be installed between the two power supplies. 3.1.19 When the main step-down substation or 6-10 kV high-voltage distribution station is connected to a high-voltage motor, in the humid tropical area or the environment where the high-voltage motor is located is humid and there are no moisture-proof measures, a power supply for heating and drying the high-voltage motor when it is stopped should be installed. When the drying power supply is connected by the high-voltage switch cabinet, there should be measures to lock the circuit breaker to prevent misoperation.
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3.2 Low-voltage power distribution system
The low-voltage power distribution voltage is 380/220V, and the three-phase load is connected to 380V. The single-phase load is connected to 380V or 220V.
The voltage of lighting fixtures is single-phase 220V. The maintenance lighting in special environments uses 36V or 12V.
3.2.2 In the low-voltage power distribution system with 380/220V neutral point directly grounded, the connection group of the workshop transformer should be D, yn type. 3.2.3·The workshop substation with mainly secondary loads should be equipped with two transformers: The workshop substation with mainly tertiary loads can be equipped with one transformer: However, if there are some secondary loads, low-voltage interconnection lines from different buses should be connected from other substations to meet the requirements of secondary load power supply reliability.
3.2.4 The low-voltage side of the workshop substation should adopt a single busbar or a single busbar segmented connection. The low-voltage system of the workshop substation should be compatible with the process production system, and the electrical equipment of the same production system should be powered by the same busbar. 3.2.5 Load rate of the workshop substation transformer 3.2.5.1 When two transformers are used for power supply at the same time, when one is disconnected, the other can carry 70% to 100% of the production load.
3.2.5.2 When more than two transformers are used for power supply at the same time, when one is disconnected, the remaining transformers can carry 100% of the production load. 3.2.5.3 When three transformers are selected and one of them is used as a public standby, a load rate of 80% can be considered.
When a single transformer is selected for power supply, the load rate should be less than 80%. 3.2.5.5 The transformer capacity should also be verified according to the starting and self-starting conditions of the motor.
3.2.6 The main circuit breaker and busbar section circuit breaker on the low-voltage side of the transformer generally use low-voltage circuit breakers with delayed overcurrent releases. 7
The workshop substation should be set outside the explosion-hazardous area 3.2.73
3.2.8 Lighting generally shares the power supply of the transformer with the power load. When the power supply voltage deviation often exceeds the rated value ±5%, in order to ensure the power supply quality of lighting, it is advisable to separate the power supply from the lighting, and set up a dedicated lighting transformer to form an independent lighting power supply system.
Each production device and workshop should have a maintenance power supply. A certain number of maintenance power switch boxes and sockets should be set up as needed: the power supply range can be considered as 30m, and a trunk distribution system should be adopted.
3.2.10 In a 380/220V neutral point directly grounded network, single-phase 220V loads should be distributed as evenly as possible in the three-phase line. The connection group is Y, y. For three-phase transformers of this type, the neutral current shall not exceed 25% of the rated current of the low-voltage winding. And the current of one phase shall not exceed the rated current value when fully loaded. For transformers of other connection groups, if their manufacturing standards have other provisions, they may not be subject to this restriction. 3.3
Voltage level
3.3.1 In order to ensure the quality of power supply, according to the requirements of various electrical equipment, the following voltage deviation allowable values should be verified during design. 3.3.1.1 Terminal voltage of motor:
(1) ±5% under normal circumstances;
(2) +5%, -10% under special circumstances.
3.3.1.2 Terminal voltage of lighting fixtures:
(I) In general workplaces
(2) In indoor places with high visual requirements (except gas discharge lamps) -2.5%;
(3) Emergency lighting, road lighting and 12~36V maintenance lighting 1+5%, -10%.
3.3.1.3 Terminal voltage of other electrical equipment: unless otherwise specified
±5%.
W.6
Convenient for transportation of main equipment
As close to the load center as possible while meeting the above conditions. It should be an independent building with the conditions for expansion as needed. Main step-down substation or main distribution station
Distance requirements from certain environments
Explosion-hazardous environment
Medium-corrosive environment
Strongly corrosive environment
Fire-hazardous places
Table 3.1.14.2
Refers to explosion-hazardous devices
and buildings
6~10kV secondary distribution stations should not be connected to explosion-hazardous chemical production equipment: (including upstairs or downstairs), and should be located outside the explosion-hazardous area and corrosion area of the chemical production equipment.
3.1.16 The workshop transformer adopts the line-to-transformer group wiring method. The isolating switch may not be installed on the high-voltage side of the workshop transformer site. When the workshop substation is equipped with two transformers, its power supply line should be connected to different bus sections of 6-10 kV high-voltage distribution station.
3.1.17: When there may be power feedback in the 6-10 kV outgoing line circuit, if it is a fixed switch cabinet, an isolating switch should be installed behind the circuit breaker. 3.1.18 The main step-down substation or main distribution station should have two power supplies. A backup power automatic input device should be installed between the two power supplies. 3.1.19 When the main step-down substation or 6-10 kV high-voltage distribution station is connected to a high-voltage motor, in the humid tropical area or the environment where the high-voltage motor is located is humid and there are no moisture-proof measures, a power supply for heating and drying the high-voltage motor when it is stopped should be installed. When the drying power supply is connected by the high-voltage switch cabinet, there should be measures to lock the circuit breaker to prevent misoperation.
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3.2 Low-voltage power distribution system
The low-voltage power distribution voltage is 380/220V, and the three-phase load is connected to 380V. The single-phase load is connected to 380V or 220V.
The voltage of lighting fixtures is single-phase 220V. The maintenance lighting in special environments uses 36V or 12V.
3.2.2 In the low-voltage power distribution system with 380/220V neutral point directly grounded, the connection group of the workshop transformer should be D, yn type. 3.2.3·The workshop substation with mainly secondary loads should be equipped with two transformers: The workshop substation with mainly tertiary loads can be equipped with one transformer: However, if there are some secondary loads, low-voltage interconnection lines from different buses should be connected from other substations to meet the requirements of secondary load power supply reliability.
3.2.4 The low-voltage side of the workshop substation should adopt a single busbar or a single busbar segmented connection. The low-voltage system of the workshop substation should be compatible with the process production system, and the electrical equipment of the same production system should be powered by the same busbar. 3.2.5 Load rate of the workshop substation transformer 3.2.5.1 When two transformers are used for power supply at the same time, when one is disconnected, the other can carry 70% to 100% of the production load.
3.2.5.2 When more than two transformers are used for power supply at the same time, when one is disconnected, the remaining transformers can carry 100% of the production load. 3.2.5.3 When three transformers are selected and one of them is used as a public standby, a load rate of 80% can be considered.
When a single transformer is selected for power supply, the load rate should be less than 80%. 3.2.5.5 The transformer capacity should also be verified according to the starting and self-starting conditions of the motor.
3.2.6 The main circuit breaker and busbar section circuit breaker on the low-voltage side of the transformer generally use low-voltage circuit breakers with delayed overcurrent releases. 7
The workshop substation should be set outside the explosion-hazardous area 3.2.73
3.2.8 Lighting generally shares the power supply of the transformer with the power load. When the power supply voltage deviation often exceeds the rated value ±5%, in order to ensure the power supply quality of lighting, it is advisable to separate the power supply from the lighting, and set up a dedicated lighting transformer to form an independent lighting power supply system.
Each production device and workshop should have a maintenance power supply. A certain number of maintenance power switch boxes and sockets should be set up as needed: the power supply range can be considered as 30m, and a trunk distribution system should be adopted.
3.2.10 In a 380/220V neutral point directly grounded network, single-phase 220V loads should be distributed as evenly as possible in the three-phase line. The connection group is Y, y. For three-phase transformers of this type, the neutral current shall not exceed 25% of the rated current of the low-voltage winding. And the current of one phase shall not exceed the rated current value when fully loaded. For transformers of other connection groups, if their manufacturing standards have other provisions, they may not be subject to this restriction. 3.3
Voltage level
3.3.1 In order to ensure the quality of power supply, according to the requirements of various electrical equipment, the following voltage deviation allowable values shall be verified during design. 3.3.1.1 Terminal voltage of motor:
(1) ±5% under normal circumstances;
(2) +5%, -10% under special circumstances.
3.3.1.2 Terminal voltage of lighting fixtures:
(I) In general workplaces
(2) In indoor places with high visual requirements (except gas discharge lamps) -2.5%;
(3) Emergency lighting, road lighting and 12~36V maintenance lighting 1+5%, -10%.
3.3.1.3 Terminal voltage of other electrical equipment: unless otherwise specified
±5%.
W.8 Lighting is generally powered by the same transformer as the power load. When the power supply voltage deviation often exceeds the rated value ± 5%, in order to ensure the power supply quality of lighting, it is advisable to separate the power supply from the lighting, and set up a dedicated lighting transformer to form an independent lighting power supply system.
Each production device and plant should have a maintenance power supply. A certain number of maintenance power switch boxes and sockets should be set up as needed: the power supply range can be considered as 30m, and a trunk distribution system should be adopted.
3.2.10 In a 380/220V neutral point directly grounded network, the single-phase 220V load should be distributed as evenly as possible in the three-phase line. For a three-phase transformer with a connection group of Y, y. type, the neutral line current shall not exceed 25% of the rated current of the low-voltage winding. And the current of one phase shall not exceed the rated current value when fully loaded. For transformers of other connection groups, if their manufacturing standards have other provisions, they may not be subject to this restriction. 3.3
Voltage level
3.3.1 In order to ensure the quality of power supply, according to the requirements of various electrical equipment, the following voltage deviation allowable values should be verified during design. 3.3.1.1 Terminal voltage of motor:
(1) ±5% under normal circumstances;
(2) +5%, -10% under special circumstances.
3.3.1.2 Terminal voltage of lighting fixtures:
(I) In general workplaces
(2) In indoor places with high visual requirements (except gas discharge lamps) -2.5%;
(3) Emergency lighting, road lighting and 12~36V maintenance lighting 1+5%, -10%.
3.3.1.3 Terminal voltage of other electrical equipment: When there is no special provision,
±5%.
W.8 Lighting is generally powered by the same transformer as the power load. When the power supply voltage deviation often exceeds the rated value ± 5%, in order to ensure the power supply quality of lighting, it is advisable to separate the power supply from the lighting, and set up a dedicated lighting transformer to form an independent lighting power supply system.
Each production device and plant should have a maintenance power supply. A certain number of maintenance power switch boxes and sockets should be set up as needed: the power supply range can be considered as 30m, and a trunk distribution system should be adopted.
3.2.10 In a 380/220V neutral point directly grounded network, the single-phase 220V load should be distributed as evenly as possible in the three-phase line. For a three-phase transformer with a connection group of Y, y. type, the neutral line current shall not exceed 25% of the rated current of the low-voltage winding. And the current of one phase shall not exceed the rated current value when fully loaded. For transformers of other connection groups, if their manufacturing standards have other provisions, they may not be subject to this restriction. 3.3
Voltage level
3.3.1 In order to ensure the quality of power supply, according to the requirements of various electrical equipment, the following voltage deviation allowable values should be verified during design. 3.3.1.1 Terminal voltage of motor:
(1) ±5% under normal circumstances;
(2) +5%, -10% under special circumstances.
3.3.1.2 Terminal voltage of lighting fixtures:
(I) In general workplaces
(2) In indoor places with high visual requirements (except gas discharge lamps) -2.5%;
(3) Emergency lighting, road lighting and 12~36V maintenance lighting 1+5%, -10%.
3.3.1.3 Terminal voltage of other electrical equipment: When there is no special provision,
±5%.
W.
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