Electric actuators are used in very harsh working conditions,often with a lot of flammable and explosive gas mixture,therefore, the explosion-proof function of the electric actuator is highly required, so as to ensure the safety and effectiveness of the electric actuator.Taking the explosion-proof electric actuator produced by the Sino-British joint venture Tandy Valve as an example, this paper analyzes how to design the explosion-proof structure of the electric actuator.
An electric actuator with a flameproof enclosure. The flameproof enclosure can withstand an explosion inside a combustible mixture that has entered the outer shell without damaging it bad, and does not ignite the external explosion of one or more gases or vapors through any joint or structural holes on the housing electric actuator housing for the environment.
An electric actuator that does not generate electric arc and spark under normal operating conditions is adopted to take some additional measures to improve its safety, defense An electric actuator that prevents dangerous temperatures, arcs, or sparks from appearing on external parts of its internal box.
Intrinsic safety usually refers to a system and not to a device. People usually say that a transmitter or sensor or sensor is essential.When secure, this is a simplified term, in fact inherently safe refers to an essential safety system consisting of a transmitter or sensor via cable and associated equipment (security grids, etc.).
Intrinsic safety circuit means any spark or any thermal effect produced under specified conditions (including normal working and prescribed conditions) shall not ignite the specified explosive gas environment.
本質安全設備
Intrinsic safety equipment
本質安全設備指在其內部的所有電路都是本質安全電路的電動執行器。
Intrinsic safety equipment means that all the internal circuits are essential safety circuits of electric actuators.
The device is an electric actuator with intrinsic safety circuit and non-essential safety circuit, and its structure prevents the non-essential safety circuit from having an adverse effect on the intrinsic safety circuit. Other forms of explosion-proof enclosure protection should be added when the associated equipment is installed and used in dangerous places, such as flame-proof type, positive-pressure type, etc. For installation and use in a safe place, the housing may be of the general type. Motor actuators with electrical connections to intrinsic safety equipment, limited voltage in the interface part, and limited current limiter ( limited energy) can be considered to be associated with an electric actuator in an intrinsic safety system, Such as Zener Safety Grid, Isolated Safety Grid, Intrinsic Safety Power Supply, Photoelectric Isolation Interface Electrical Equipment, etc.
4、正壓型電動執行器“p”
4.Positive Pressure Type Electric Actuators "p"
一種通過保持內部保護氣體的壓力高于周圍爆炸性環境壓力的措施來達到安全的電動執行器。
An electric actuator that achieves safety by keeping the pressure of an internal protective gas above the surrounding explosive ambient pressure.
The whole equipment or part of it is put in a pouring agent and cannot ignite the electric actuators of the surrounding explosive mixture under normal operation and in case of an approved overload or failure of approval.
