Increased Safety Structure is widely used in explosion-proof electrical equipment, such as motors, transformers, lighting fixtures, and electrical equipment with inductive coils. Generally, the allowable temperature rise of the insulated winding should be 10°C lower than the standard temperature rise specified for other explosion-proof electrical equipment. The leakage distance and electrical clearance should be as large as possible, with the relevant values not below the specified requirements. The housing should have certain protective measures and meet the IP54 protection requirements as stipulated in GB1498-79. The motor should allow a minimum blocking time of tEzui of not less than 5 seconds, and the ratio of starting current to rated current should not exceed 10 times.

The temperature rise within the allowable blocking time must not pose a risk of ignition or explosion, nor should it damage the insulation. The inter-turn and ground test voltages of the insulated windings must be higher than those of standard electrical equipment. Low-voltage equipment should be increased by 10%, and high-voltage equipment by 30%. It is also required that all conductor connections be reliable, and that poor contact should not occur under conditions such as overload and vibration. Increased safety electrical equipment, although safe to use in environments with higher explosion hazards, cannot guarantee explosion-proof safety if internal components fail. Therefore, careful consideration must be given to the operating environment, maintenance, and other conditions before determining if it is suitable for selection. When selecting increased safety motors, transformers, and other equipment, corresponding overload protection devices or overheating devices must be installed.

Additionally, squirrel-cage induction motors must be adequately protected, and their operation must not exceed the permissible plug-up time value tD. Electrical equipment with ventilation and inflation structures relies on supplied protective gases and protective devices to ensure explosion-proof performance. Therefore, it is necessary to install the most suitable protective devices based on the level of explosion hazard in the usage area and whether the equipment frequently sparks. In general, there should be no ventilation dead spots inside the electrical equipment that could affect safety. During normal operation, the wind pressure or inflation pressure at the outlets should not be less than 10 mmHg; otherwise, an alarm should be immediately issued or the power supply should be cut off. Spark arcs inside the equipment are not allowed to escape through any gaps or outlets. Ventilation and inflation structures are used in equipment where internal components are prone to damage or in larger electrical equipment, or in electrical equipment that is difficult to manufacture in other explosion-proof structures, such as those with auto-ignition points T4 and T5.

Explosion-proof oil-filled structures are not related to the explosion-proof grade and are suitable for small operating switches. The surface temperature and oil temperature of explosion-proof oil-filled structures must not exceed the specifications in Table 1-1 even when the operating frequency and current intensity may reach severe overload. This requirement applies not only to this structure but to all explosion-proof structures. The depth of the cold oil layer (the distance from the oil surface to the part where sparks or arcs are generated) should be twice the minimum test protection depth, but not less than 10 millimeters. The oil used in explosion-proof electrical equipment filled with oil should have high chemical stability. To observe the oil level, the equipment should be equipped with an oil level indicator or an oil level signaling device. Switches, controllers, and other equipment with oil-immersed explosion-proof structures are difficult to repair due to oil degradation or leakage.

Please note: The equipment must not be used further if its explosion-proof performance is compromised due to tilting or oil surface movement. Intrinsically safe structure - Intrinsically safe explosion-proof structures are only suitable for low-current circuits, such as on small electrical equipment like test instruments and control devices. In both normal and abnormal conditions, electric sparks or dangerous temperatures will not ignite explosive substances, making this structure a highly secure explosion-proof design. All components on the circuit or equipment must have surface temperatures below the specified limit to prevent ignition caused by thermal effects.

Electrical circuits with intrinsic safety explosion-proof structures must be isolated from other circuits to prevent cross-wiring electromagnetic or static induction, especially external wiring of the structure. Rigorous measures must be taken to ensure the explosion-proof performance of electrical equipment and wiring. Special explosion-proof electrical equipment refers to explosion-proof structures other than the aforementioned typical structural types. Therefore, due consideration must be given to additional usage conditions recognized by the authorized inspection authority.