In electrical terms, two three-way connectorssolenoid valveGenerally, it is a single coil electric control, while a two position five way solenoid valve is a dual coil electric control. The voltage level of the coil is generally DC24V, AC220V, etc. Two five way solenoid valves have one inlet hole (connected to the air source), one forward acting air hole, and one reverse acting air hole (providing one forward and one reverse acting air source to the target device respectively), one forward acting exhaust hole, and one reverse acting exhaust hole (equipped with a muffler). For small automatic control equipment, industrial rubber hoses with a diameter of 8-12mm are generally used for the air pipes. Electromagnetic valves are generally selected from Japanese SMC (high-end, but small Japanese products), Taiwanese Yadeke (affordable and of good quality), or other domestic brands. Two position three-way solenoid valves are divided into two types: normally closed and normally open. The normally closed type refers to the air circuit being disconnected when the coil is not powered, while the normally open type refers to the air circuit being connected when the coil is not powered. The operating principle of a normally closed two position three-way solenoid valve is to energize the coil and connect the air circuit. Once the coil is powered off, the air circuit will be disconnected, which is equivalent to "inching". The operating principle of a normally open two position three-way single electric control solenoid valve is: when the coil is energized, the air circuit is disconnected. Once the coil is de energized, the air circuit will be connected, which is also called "inching". The principle of action of two five way dual electric control solenoid valves: When the positive action coil is energized, the positive action air circuit is connected (there is air in the positive action air hole). Even if the positive action coil is powered off, the positive action air circuit is still connected and will be maintained until the reverse action coil is energized. If the reverse action coil is powered on, the reverse action air path will be connected (there is air in the reverse action air hole). Even if the reverse action coil is powered off, the reverse action air path will still be connected and will be maintained until the positive action coil is powered on. This is equivalent to 'self-locking'. Based on the characteristic of two five way dual electric control solenoid valves, when designing electromechanical control circuits or programming PLC programs, the solenoid valve coil can be operated for 1-2 seconds to protect it from damage.