Safety distance and related safety requirements

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Safety distance and related safety requirements [Copy link]

1. Electrical clearance: the shortest distance between two adjacent conductors or between a conductor and the adjacent motor housing surface measured along the air. 2. Creepage distance: The shortest distance between two adjacent conductors or between a conductor and the adjacent motor casing surface measured along the insulating surface. Determination of electrical clearance: The distance can be determined based on the measured working voltage and insulation level. For the electrical clearance dimension requirements of the primary side line, see Table 3 and Table 4. For the electrical clearance dimension requirements of the secondary side line, see Table 5. But usually: Primary side AC part: L-N ≥ 2.5mm before fuse, LN PE (earth) ≥ 2.5mm, no requirement is made after fuse installation, but keep a certain distance as much as possible to avoid short circuit and damage to the power supply. Primary side AC to DC part ≥2.0mm Primary side DC ground to earth ≥2.5mm (primary side floating ground to earth) Primary side to secondary side ≥4.0mm, components bridged between primary and secondary sides Gap gap of secondary side ≥0.5mm The distance between the secondary side and the ground shall be ≥1.0mm Note: Before deciding whether it meets the requirements, the internal parts should be subjected to a force of 10N and the outer casing to a force of 30N to reduce the distance between them so that the spatial distance still meets the requirements under the worst condition. Creepage distance determination: Creepage distance can be determined by referring to Table 6 according to the working voltage and insulation grade. But usually: (1) Primary side AC part: L—N ≥ 2.5mm before fuse, L N The ground is ≥2.5mm, and there is no requirement after the fuse, but try to keep a certain distance to avoid short circuit and damage to the power supply. (2) The primary side AC to DC part ≥ 2.0mm (3) The primary side DC ground to ground ≥ 4.0mm such as the primary side ground to earth (/size) (/font) (/color) (color=#000000) (4) The distance between the primary side and the secondary side should be ≥6.4mm. For example, if the pitch between the pins of components such as optocouplers and Y capacitors is ≤6.4mm, grooves should be cut. (5) The distance between the secondary parts shall be ≥0.5mm (6) The distance between the secondary side and the ground shall be ≥2.0mm (7) The distance between the two poles of the transformer shall be ≥8.0mm or more 3. Insulation penetration distance: It should meet the following requirements according to the working voltage and insulation application occasions: - For working voltage not exceeding 50V (71V AC peak value or DC value), there is no thickness requirement; ——The minimum thickness of the additional insulation should be 0.4mm; ——When the reinforced insulation is not subjected to any mechanical stress that may cause deformation or performance degradation of the insulating material at normal temperature, the minimum thickness of the reinforced insulation should be 0.4mm. If the insulation provided is used in the protective casing of the equipment and will not be bumped or scratched during maintenance by the operator, and it belongs to any of the following conditions, the above requirements do not apply to thin insulating materials regardless of their thickness; -For additional insulation, at least two layers of material are used, each of which can pass the dielectric strength test for additional insulation; or: -For additional insulation composed of three layers of material, the combination of any two layers of material can pass the dielectric strength test for additional insulation; or: - For reinforced insulation, at least two layers of material are used, each of which can pass the dielectric strength test for reinforced insulation; or: - For reinforced insulation consisting of three layers of insulating material, the combination of any two layers of material can pass the dielectric strength test for reinforced insulation. 4. Notes on wiring process: Flat components such as capacitors must be laid flat without glue. If the distance between two conductors can be shortened by applying a force of 10N and is less than the safety distance requirement, glue can be used to fix the parts to ensure their electrical clearance. When laying PVC film inside some shell equipment, attention should be paid to ensuring the safety distance (pay attention to the processing technology) When gluing and fixing parts, pay attention not to allow foreign matter such as glue wire on the PCB board. When processing parts, insulation damage should not be caused. 5. Requirements for flame retardant materials: Heat shrink tubing V-1 or VTM-2 or above; PVC tubing V-1 or VTM-2 or above Teflon tube V-1 or VTM-2 or above; plastic materials such as silicone sheets, insulating tape V-1 or VTM-2 or above PCBBoard 94V-1 or above 6, about insulation level (1) Working insulation: Insulation required for normal operation of equipment (2) Basic insulation: Insulation that provides basic protection against electric shock (3) Supplementary insulation: Independent insulation applied in addition to basic insulation to prevent electric shock in the event of failure of the basic insulation. (4) Double insulation: Insulation consisting of basic insulation plus supplementary insulation (5) Reinforced insulation: A single insulation structure which, under the conditions specified in this standard, provides the same level of protection against electric shock as double insulation (6) Reinforced insulation: A single insulation structure which, under the conditions specified in this standard, provides the same level of protection against electric shock as double insulation (7) Reinforced insulation: A single insulation structure which, under the conditions specified in this standard, provides the same level of protection against electric shock as double insulation (8) Reinforced insulation: A single insulation structure which, under the conditions specified in this standard, provides the same level of protection against electric shock as double insulation (9) Reinforced insulation: A single insulation structure which, under the conditions specified in this standard, provides the same level of protection against electric shock as double insulation (10) A, Operational Insulationinsulation a,between two parts of different voltages b, between ELV circuit (or SELV circuit) and grounded conductive parts. B, basic insulation a, between parts with hazardous voltage and earthed conductive parts; b, between parts with hazardous voltage and earthed SELV circuits; c. Between the primary power conductor and the grounded shield or the core of the main power transformer; d. As part of double insulation. C, Supplementary insulationsupplementary insulationa, Generally speaking, between accessible conductive parts and parts which may carry dangerous voltage after damage of basic insulation, such as:I, Between the surface of handles, knobs, lifting handles or similar and their unearthed axis. Ⅱ. Between the metal casing of the second type of equipment and the outer sheath of the power cord passing through this casing. Ⅲ. Between the ELV circuit and the ungrounded metal casing. b, as part of double insulation D, double insulation Double insulation Reinforced insulation Generally speaking, between the primary circuit and a, between accessible ungrounded conductive parts, or b, between floating SELV circuits, or c, between TNV circuits Double insulation = basic insulation + supplementary insulation Note: ELV line: Extra low voltage circuit Under normal working conditions, the AC peak value between conductors or between any conductors shall not exceed 42.4V or a secondary circuit with a DC value not exceeding 60V. SELVCircuit: Safety Extra Low Voltage Circuit. A properly designed and protected secondary circuit so that under normal conditions or single fault conditions, the voltage between any two accessible parts, and between any accessible parts and the protective earthing terminal of the equipment (only for Class I equipment) will not exceed the safe value. TNV: Communication network voltage circuit A circuit that carries communication signals under normal working conditions.