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GB 50994-2014: Standard for seismic appraisal of electrical facilities in industrial plants
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GB 50994-2014: Standard for seismic appraisal of electrical facilities in industrial plants

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1 General 1.0.1 This standard is formulated in order to make the existing electrical equipment of industrial enterprises (hereinafter referred to as. electrical equipment) reach the seismic fortification standard after the seismic identification and anti-seismic measures are taken, so as to reduce the earthquake damage of electrical equipment, avoid casualties, and reduce economic losses.. 1.0.2 This standard applies to areas where the design basic seismic acceleration value is not greater than 0.40g (that is, the seismic fortification intensity is 9 degrees and below), and the industrial enterprises with a voltage level of 220kV and below have power transformers, reactors, circuit breakers, and lightning arresters., current (voltage) transformer, electric porcelain equipment, power capacitor bank (cabinet), battery pack (cabinet), switchgear, converter cabinet, control (protection) screen, DC screen, emergency power supply unit and combined electrical appliances and other electrical equipment Anti-seismic identification and anti-seismic measures to be taken. This standard does not apply to the seismic identification of existing electrical equipment in industrial enterprises where the design basic seismic acceleration value is greater than 0.40g or where there are special requirements. 1.0.3 The electrical equipment that has undergone seismic identification and anti-seismic measures in accordance with this standard shall not be seriously damaged when subjected to earthquakes of the local seismic fortification intensity and below, and can continue to supply power after simple maintenance. 1.0.4 The design basic earthquake acceleration is 0.05g (that is, the seismic fortification intensity is 6 degrees) and above the electrical equipment in the area without seismic fortification. Seismic identification must be carried out and necessary seismic measures must be taken. 1.0.5 The design basic seismic acceleration value and seismic fortification intensity shall be determined according to the relevant provisions of the current national standard "Zoning Map of Earthquake Motion Parameters in China" GB 18306;, the seismic identification can be carried out according to the approved design ground motion parameters or seismic fortification intensity. 1.0.6 The seismic appraisal of electrical equipment shall not only comply with the provisions of this standard, but also comply with the provisions of the current relevant national standards.

2 Terminology and symbols

2.1 Terminology 2.1.1 Seismic measures Seismic design content other than seismic action calculation and resistance calculation, including seismic structural measures. 2.1.2 Seismic precaution The engineering and non-engineering defense measures taken by various engineering structures in accordance with the specified reliability requirements for the possible earthquake hazards. 2.1.3 Seismic precautionary criterion The scale to measure the level of seismic fortification requirements is determined by the seismic fortification intensity or the design ground motion parameters and the structure's seismic fortification category. 2.1.4 Seismic precautionary intensity The seismic intensity approved as the basis for an area's seismic fortification according to the authority stipulated by the state. Generally, the seismic intensity is taken as the probability of exceeding 10% within 50 years. 2.1.5 Seismic appraisal By checking the design, construction quality and status quo of existing projects, and according to the specified seismic fortification requirements, evaluate their safety under earthquake action. 2.1.6 Seismic retrofit for engineering; seismic strengthening for engineering Design and construction to make the existing engineering structure meet the requirements of seismic appraisal. 2.1.7 earthquake action earthquake action Structural dynamic action caused by ground motion, including horizontal earthquake action and vertical earthquake action. 2.1.8 seismic action effect The internal force (shear force, bending moment, axial force, torque, etc.) or deformation (linear displacement, angular displacement) of the structure generated by the earthquake. 2.1.9 Design basic acceleration of ground motion Design value of earthquake acceleration with 10% probability of exceeding in the 50-year design base period. 2.2 Symbols 2.2.1 Earthquake action and action effect F——Earthquake action of electrical equipment (structure); m - the mass of electrical equipment; mi—mass concentrated at the operating state of particle i; M - bending moment; T - the natural vibration period of the structure; Tg - characteristic period; σ——tensile (compressive) stress; τ——shear stress; g - acceleration due to gravity. 2.2.2 Material properties E - modulus of elasticity of the material; K——lateral stiffness of the system; σ——tensile (compressive) stress; τ——shear stress; [σ] — design value of allowable stress; [τ] — design value of allowable shear stress. 2.2.3 Geometric parameters A - cross-sectional area; d - the inner diameter of the circular section; D - the outer diameter of the circular section; H - the height of the structure; Hi——calculated height of particle i; I——section moment of inertia; W - section modulus; Z——section moment. 2.2.4 Calculation coefficients k - unbalance coefficient; α—seismic influence coefficient; αmax——maximum value of seismic influence coefficient; β—floor power amplification factor; λ——stiffness reduction coefficient; γ—mode shape participation coefficient.

3 basic rules

3.0.1 Electrical equipment shall be divided into important electrical equipment and general electrical equipment according to the following requirements. 1 Important electrical equipment. electrical equipment with a voltage level of 110kV and 220kV or the electrical equipment that supplies power to the enterprise's primary power load, and other electrical equipment that must ensure power supply during an earthquake; 2 General electrical equipment. electrical equipment other than item 1. 3.0.2 When electrical equipment is subjected to seismic appraisal, its visual inspection shall meet the following requirements. 1 The equipment itself should not be damaged, and the electric porcelain parts should have no cracks; 2 The electrical connection should be reliable, the fixing bolts should be intact, and the nuts should not be loose; 3 The connection between the equipment and the foundation or supporting structure should be firm; 4 The weld seam should have no cracks, and the metal parts should have no serious corrosion; 5 The supporting frame and accessories of the equipment should not be deformed or damaged. 3.0.3 The earthquake impact on the area where the electrical equipment is located can be characterized by the following ground motion parameters. 1 Design basic seismic acceleration or seismic fortification intensity; 2 characteristic period. 3.0.4 The corresponding relationship between the design basic seismic acceleration value and the seismic fortification intensity shall comply with the provisions in Table 3.0.4. Table 3.0.4 Correspondence between design basic seismic acceleration value and seismic fortification intensity Note. g is the acceleration due to gravity, 9.8m/s2. 3.0.5 Electric equipment such as power transformers, three-phase vertically arranged reactors and lightning arresters, circuit breakers and porcelain bushings shall be checked against earthquakes when one of the following conditions exists. 1 Areas where the design basic seismic acceleration value is 0.20g and above; 2 The design basic seismic acceleration value is 0.10g and 0.15g areas, and the voltage level is 110kV and 220kV; 3 Design the area where the basic seismic acceleration value is 0.15g, and the height of the floor or support for placing electrical equipment is greater than 2.0m. 3.0.6 The following electrical equipment may not be subject to seismic calculation, but the seismic identification and anti-seismic measures shall be taken for the fixing method and body structure. 1 Power capacitor group (cabinet), battery group (cabinet), switchgear, converter cabinet, control (protection) panel, DC panel, emergency power supply unit, combined electrical appliances and other electrical equipment; 2 Cabinet racks for placing electrical equipment, etc.; 3 Electrical equipment other than those specified in Article 3.0.5 of this standard. 3.0.7 For important electrical equipment, the seismic action calculation shall be carried out according to the design basic seismic acceleration value of the region, and seismic measures shall be taken according to the seismic fortification intensity increase of one degree; when the seismic fortification intensity is 9 degrees, the earthquake action calculation shall be The design basic seismic acceleration value can no longer be increased, and the requirements for anti-seismic measures can be appropriately increased. 3.0.8 When the electrical equipment does not meet the requirements for seismic identification, anti-seismic measures or shock-absorbing measures shall be taken according to Appendix A of this standard. 3.0.9 Unless otherwise specified in this standard, the allowable stress design value used in the seismic check calculation of electrical equipment shall be selected according to the following provisions. 1 The elastic material may be 1.4 times the allowable stress at the design temperature of the material, but not greater than 0.9 times the yield strength of the material at the design temperature; 2 Brittle materials may be 1.2 times the design value of the tensile strength of the material or 0.6 times the failure stress value at the design temperature of the material. 3.0.10 All kinds of electrical equipment should be reliably fixed on the foundation, support or cabinet frame, and the anchor bolts or welding strength of the equipment should meet the seismic fortification requirements. 3.0.11 In areas where the design basic seismic acceleration value is 0.20g and above, the power distribution equipment with high-level layout or multi-layer layout should be changed to low-level layout or anti-seismic measures should be taken, and the tubular busbar should be in the form of suspension. 3.0.12 It is advisable to use flexible wires for the connection between the lead wires of electrical equipment and the equipment, and the length should have a margin. When hard bus connection is used, expansion joint transition should be added. 4.Seismic Appraisal 4.1 Power transformers Ⅰ General Provisions 4.1.1 Power transformers shall include transformers and arc suppression coils. 4.1.2 During the seismic appraisal of power transformers, the installation method, the connection method of the lead wire and the outside, the strength of the oil conservator support and the cantilever of the radiator should be inspected emphatically. 4.1.3 When the seismic fortification intensity is 7 degrees or above, the seismic check shall be carried out according to the relevant provisions in Chapter 5 of this standard. Ⅱ Seismic Appraisal 4.1.4 The seismic identification of transformers and arc suppression coils shall meet the following requirements. 1 Transformer and arc suppression coil should be fixed with the foundation; 2 The bus bar connecting the transformer with the outside should be set with soft connection; 3 The oil conservator bracket of the transformer should have no obvious deformation, and the connection between the bracket, the transformer body and the oil conservator should be firm; 4 The cantilever radiator and connection of the transformer should be in good condition. 4.1.5 The connecting pipe between the separately set oil cooler and the transformer body shall be provided with a shut-off valve and a flexible joint near the transformer. 4.1.6 There should be fixing measures for the transformer on the pole. Ⅲ Seismic measures 4.1.7 If the transformer and arc-suppression coil do not meet the seismic identification requirements of this section, anti-seismic measures shall be taken according to the following provisions. 1 The transformer and arc suppressing coil shall be directly fixed on the foundation by means of anchor bolts or welding, and shall not only adopt limit measures; 2 When the transformer bushing is connected with flexible wires, it should be properly loosened; when the insulation spacing does not meet the requirements, spring clamps can be used; when hard busbars are used for connection and the cross-sectional size is greater than 50mm×5mm, a soft connection should be added; 10kV For distribution transformers up to and below, when the seismic fortification intensity is 6 degrees or 7 degrees, a soft connection should be added; when the seismic fortification intensity is 8 degrees or 9 degrees, a soft connection should be added; 3 The cantilever radiator of the transformer can be supported by angle steel brackets fixed on the transformer body or connected circularly along the radiator with flat steel. 4.1.8 For the connection pipe between the separately installed oil cooler and the transformer body, a cut-off valve and a flexible joint shall be provided near the transformer, and the distance between the radiator, submersible oil pump and the connection pipe and the foundation shall not be less than.200mm. 4.1.9 The lower part of the transformer on the pole should be fixed with bolts and the lower beam; when the seismic fortification intensity is 8 degrees and above, measures should also be taken between the upper part and the pole. 4.2 Three-phase vertically arranged reactor Ⅰ General Provisions 4.2.1 Three-phase vertically arranged reactors shall include three-phase vertically arranged cement reactors and three-phase vertically arranged dry-type air-core reactors. 4.2.2 During the seismic appraisal of three-phase vertically arranged reactors, the type and installation method of the reactors should be mainly checked. 4.2.3 When the seismic fortification intensity is 7 degrees and above, three-phase vertically arranged cement reactors and when the seismic fortification intensity is 8 degrees and above, three-phase vertically arranged dry-type air-core reactors shall be checked according to Chapter 5 of this standard. Ⅱ Seismic Appraisal 4.2.4 The seismic appraisal of three-phase vertically arranged reactors shall meet the following requirements. 1 Three-phase vertically arranged reactors should be dry-type air-core reactors; 2 Three-phase reactors should be arranged horizontally. Ⅲ Seismic measures 4.2.5 When three-phase vertically arranged reactors do not meet the requirements for seismic identification in this section, anti-seismic measures shall be taken according to the following provisions. 1 When the seismic fortification intensity is 6 or 7, the three-phase vertically arranged cement reactor should be replaced with a dry-type air-core reactor; when the seismic fortification intensity is 8 or 9, it should be replaced with a dry-type air-core reactor; 2 Three-phase vertically arranged reactors should be changed to three-phase horizontally arranged when site conditions permit. 4.2.6 Three-phase vertically arranged cement reactors and three-phase vertically arranged dry-type air-core reactors in areas with seismic fortification intensity 8 degrees and above, if the seismic check calculation does not meet the seismic requirements, the methods in Appendix B of this standard can be used for seismic reinforcement. 4.2.7 In areas with seismic fortification intensity of 7 degrees and below, three-phase vertically arranged dry-type air-core reactors or three-phase horizontally arranged cement reactors supporting porcelain bottles, if the anti-seismic requirements are not met after seismic calculation, the supporting porcelain bottles should be replaced with stronger ones. Tall vase. 4.3 Circuit breaker, surge arrester Ⅰ General Provisions 4.3.1 Circuit breakers and arresters shall include independently installed circuit breakers, self-supporting arresters and rod arresters. 4.3.2 During the seismic appraisal of circuit breakers and lightning arresters, it is necessary to focus on checking the pulling force in all directions of the porcelain bottle, the connection between the porcelain bottle and the flange, the external wires and the tie rods. 4.3.3 When the anti-seismic fortification intensity is 7 degrees or above, the circuit breaker and lightning arrester shall carry out anti-seismic calculation according to Chapter 5 of this standard. Ⅱ Seismic Appraisal 4.3.4 The seismic appraisal of circuit breakers and arresters shall meet the following requirements. 1 The porcelain bottle of the circuit breaker and lightning arrester should be in good condition; 2 The connection between the porcelain bottle and the flange should be firm; 3 The base and intermediate flange of the circuit breaker and lightning arrester should be intact, and the nuts should not be loose; 4.The external wires of the circuit breaker and lightning arrester should be softly connected or have expansion joints. 4.3.5 For lightning arresters with insulating tie rods, the pulling force of the tie rods in all directions should be uniform. Ⅲ Seismic measures 4.3.6 When the circuit breaker and lightning arrester do not meet the requirements for seismic identification in this section, anti-seismic measures shall be taken according to the following provisions or shock-absorbing measures shall be taken according to Appendix A of this standard. 1.When the porcelain bottle of the circuit breaker and lightning arrester is damaged or cracked, it should be replaced with a good porcelain bottle; 2 The connecting nuts between the porcelain bottle and the flange should be tightened; 3 If the base and intermediate flange of the circuit breaker and lightning arrester are corroded, the rust should be removed and the nuts should be tightened; 4 When the external wires of the circuit breaker and lightning arrester are connected by hard busbar or tubular busbar, soft connection or expansion joint should be added. 4.3.7 For lightning arresters with insulating tie rods, the pulling force of the tie rods in all directions should be uniform; if the strength requirements are not met or there is damage, the tie rods should be replaced. 4.4 Power capacitor bank (cabinet) Ⅰ General Provisions 4.4.1 The power capacitor bank (cabinet) should include capacitors in multiple installation forms, on the rack, under the rack, inside the cabinet, outside the cabinet, single or group. 4.4.2 During the seismic appraisal of the power capacitor bank (cabinet), the installation method and the connection with the external wires should be mainly inspected. 4.4.3 The power capacitor bank (cabinet) may not be checked against earthquakes. Ⅱ Seismic Appraisal 4.4.4 The seismic appraisal of power capacitor bank (cabinet) shall meet the following requirements. 1 The power capacitor bank (cabinet) should be fixed to the foundation; 2 The lead wires of power capacitors should be flexible wires. Ⅲ Seismic measures 4.4.5 When the power capacitor bank (cabinet) does not meet the requirements for seismic identification in this section, anti-seismic measures shall be taken according to the following provisions. 1 The base of the power capacitor bank (cabinet) shall be fixed on the supporting structure through anchor bolts; 2 Hard wires should not be used for the lead wires of power capacitors. When the seismic fortification intensity is 7-9 degrees, the hard wires should be installed with expansion joints or replaced with soft wires. 4.5 Electric porcelain equipment Ⅰ General Provisions 4.5.1 Electric porcelain equipment shall include all kinds of electrical equipment with electric porcelain as the main components, other than circuit breakers and lightning arresters. 4.5.2 During the seismic appraisal of electric porcelain equipment, the installation method, connection of porcelain parts and type of porcelain parts should be checked emphatically. 4.5.3 Electric porcelain equipment does not need to be checked against earthquakes. Ⅱ Seismic Appraisal 4.5.4 The seismic appraisal of electric porcelain equipment shall meet the following requirements. 1 The electric porcelain parts in areas with seismic fortification intensity of 7 degrees and above should be high-strength electric porcelain parts; 2 The lead wires of high-voltage electric porcelain equipment should be connected by flexible wires; 3 When the seismic fortification intensity is 8 degrees or 9 degrees, the high-voltage electric porcelain equipment with a voltage level of 110kV and above shall be arranged in a low position or in a single layer; 4 The base of the current (voltage) transformer should be fixed to the foundation. Ⅲ Seismic measures 4.5.5 When the electric porcelain equipment does not meet the requirements for seismic identification in this section, anti-seismic measures shall be taken according to the following provisions. 1 When the seismic fortification intensity is 7 degrees to 9 degrees, ordinary electric porcelain parts should be replaced with high-strength electric porcelain parts; 2 When the seismic fortification intensity is 7 to 9 degrees, the lead wires of high-voltage electric porcelain equipment should be connected by flexible wires. When hard wires are used for connection, expansion joints should be installed or replaced with soft wires; 3 When the seismic fortification intensity is 8 or 9, and the voltage level is 110kV and above, high-position or superimposed high-voltage electric porcelain equipment should adopt low-level or single-layer layout; 4 The base of the current (voltage) transformer shall be fixed on the support structure through anchor bolts. 4.6 Battery Ⅰ General Provisions 4.6.1 Storage battery equipment shall include glass cylinder battery packs and floating maintenance-free storage batteries. 4.6.2 When evaluating the shock resistance of the battery, the installation method and external wires should be inspected emphatically. 4.6.3 The storage battery does not need to be subjected to seismic calculation. Ⅱ Seismic Appraisal 4.6.4 The seismic appraisal of the battery shall meet the following requirements. 1 The storage battery should have measures to prevent displacement, tipping or falling; 2 When the seismic fortification intensity is 8 degrees or 9 degrees, there should be anti-collision measures between the cells of the glass cylinder battery pack; 3 The reinforced bracket of the glass cylinder battery shall not hinder the maintenance and inspection of the battery; 4 The batteries should be connected by flexible wires or cables. Ⅲ Seismic measures 4.6.5 When the storage battery does not meet the requirements for seismic identification in this section, anti-seismic measures shall be taken according to the following provisions. 1 The storage battery should have measures to prevent displacement, tipping or falling, which can be fixed by brackets, and the brackets should be fixed on the supporting structure; 2 When the seismic fortification intensity is 8 degrees or 9 degrees, partitions or pads shall be provided between the cells of the glass cylinder battery pack; 3 The height of the reinforcing bracket of the glass cylinder battery should be greater than the height of the center of gravity of the battery, but it should not hinder the maintenance and inspection of the battery; 4 It is advisable to use flexible wires or cables to connect the batteries, and the terminal batteries should use cables as lead wires. 4.7 Screens, cabinets, box equipment and combined electrical appliances Ⅰ General Provisions 4.7.1 Screens, cabinets, box-type equipment and combined electrical appliances shall include various switch cabinets, control panels, protective screens, distribution boxes, emergency power supplies or combined electrical appliances, etc. 4.7.2 During the seismic appraisal of screens, cabinets and boxes, the structure of the box and its installation method should be inspected emphatically. 4.7.3 Screens, cabinets, and boxes are not required to carry out seismic check calculations. Ⅱ Seismic Appraisal 4.7.4 The seismic identification of screens, cabinets and boxes shall meet the following requirements. 1 The bottom of various screens, cabinets and boxes should be fixed to the foundation; 2 The removable electrical device in the switch cabinet should have a locking mechanism; 3 The secondary cable plugs of switch cabinets and drawer cabinets should not be loose; 4 The relays and meters on the switchgear and control (protection) panel should be fixed; 5 The oil-immersed voltage transformer in the fixed switchgear shall be fixed; 6 The printed circuit plug-in and board in the control (protection) panel should not be loose; 7 When the seismic fortification intensity is 8 degrees or 9 degrees, the rows of switch cabinets, power distribution panels and control (protection) panels shall be connected as a whole. The hard busbars connected between cabinets (screens) should have soft connections where they pass through building settlement joints or expansion joints. 4.7.5 The seismic appraisal of combined electrical appliances shall meet the following requirements. 1 The combined electrical appliance should be fixed to the foundation; 2 When the seismic fortification intensity is 8 degrees or 9 degrees, the combined electrical appliances should not be installed at the settlement joints, expansion joints or seismic joints of buildings. Ⅲ Seismic measures 4.7.6 When all kinds of screens, cabinets and boxes do not meet the seismic identification requirements of this section, seismic measures shall be taken according to the following provisions. 1 The bottoms of switch cabinets, converter cabinets, control (protection) screens, DC screens and other emergency power supply devices, etc., shall be fixed on the supporting structure with anchor bolts. Set no less than 1.When the length of each piece of equipment is greater than 1.0m, the number of bolts should be increased or according to the requirements of the electrical equipment manufacturer. The bottom of the cabinet and the supporting structure can also be fixed by welding. The position and number of welding points should be the same as the bolt fixing method. The length of the seam should not be less than 40mm, and the height of the weld leg should not be less than the thickness of the weldment; 2 The removable electrical device in the switch cabinet shall be equipped with a locking mechanism; 3 The secondary cable plugs of switch cabinets and drawer cabinets shall adopt anti-loosening measures; 4 The relays and meters on the switchgear and control (protection) panel shall be fixed by bolts or clamps; 5 The oil-immersed voltage transformer in the fixed switchgear shall be fixed with the chassis by bolts; 6 The printed circuit plug-in and plug-in board in the control (protection) panel shall have locking facilities to prevent loosening; 7 When the seismic fortification intensity is 8 degrees or 9 degrees, the rows of switch cabinets, power distribution panels and control (protection) panels should be connected by bolts above the center of gravity of the equipment to form a whole. Where the building passes through the settlement joints or expansion joints, the hard busbars connected between the cabinets (screens) should adopt soft connections. 4.7.7 When the combined electrical appliances do not meet the requirements for seismic identification in this section, anti-seismic measures shall be taken according to the following provisions. 1 The base of the combined electrical appliance shall be fixed on the foundation by anchor bolts; 2 When the seismic fortification intensity is 8 degrees or 9 degrees, the combined electrical appliances should not be installed at the settlement joints, expansion joints or seismic joints of buildings.

5 seismic calculation

5.1 Calculation of earthquake action 5.1.1 The calculation method for earthquake action of electrical equipment should meet the following requirements. 1 For structures with a height of not more than 30m and shear deformation mainly and electrical equipment similar to single-mass systems (including the part above the foundation ground), simplified methods such as the bottom shear force method may be used; 2 For electrical equipment other than the above paragraph, the vibration mode decomposition response spectrum method should be adopted. 5.1.2 The seismic influence coefficient of the electrical equipment (or structure) on the ground shall be determined according to the seismic fortification intensity or design basic seismic acceleration, design seismic grouping, site category and structure natural vibration period, and structure damping ratio (Figure 5.1.2). The maximum value of the horizontal seismic influence coefficient shall be adopted in accordance with the provisions in Table 5.1.2-1; the characteristic period value shall be adopted in accordance with the provisions in Table 5.1.2-2 according to the site category and design earthquake grouping. Table 5.1.2-1 Maximum value of horizontal earthquake influence coefficient Table 5.1.2-2 Characteristic period value (s) 5.1.3 The damping adjustment and shape parameters of the seismic influence coefficient curve shall meet the following requirements. 1 When the damping ratio of the structure is 0.05, the damping adjustment coefficient of the seismic influence coefficient curve shall be adopted as 1.0, and the shape parameters shall meet the following requirements. 1) The straight-up section should be a section with a period less than 0.1s; 2) For the horizontal section, from 0.1s to the characteristic period section, the maximum value (αmax) should be taken; 3) For the descending section of the curve, from the characteristic period to 5 times the characteristic period, the attenuation index should be 0.9; 4) Straight-line descending section, from 5 times the characteristic period to 7s section... ...