Wiring Methods for Fixed-Type Combustible Gas Detectors
Combustible gas detectors are divided into two types: fixed combustible gas detectors and portable combustible gas detectors. Portable combustible gas detectors can be used simply by turning them on. Compared to portable combustible gas detectors, fixed combustible gas detectors are more cumbersome to use, especially in terms of wiring. As is well known, fixed combustible gas detectors are wired in three wire and bus systems.
Three wire wiring is mainly used in gas alarms with 4-20mA output signals. The 4-20mA output signal refers to a minimum current of 4mA and a maximum current of 20mA. This type of gas alarm is mostly wired in a split line system, where each alarm is individually wired to the gas alarm controller.
Among the three wires of a three wire alarm, one wire is the positive power supply, one wire is the positive signal, and one wire is the common negative terminal. Generally, the wiring terminals are represented by VSG. If the wiring is normal, only the VSG terminals of the gas alarm and controller corresponding channels need to be wired one by one.
Four wire system wiring
The four wire system is mostly a gas alarm with RS485 output signal, and its wiring is mostly a bus system, that is, hand in hand series wiring. In a four wire alarm system, there are generally four wiring terminals corresponding to the positive and negative power supply and the positive and negative 485 signal, respectively. The terminals are generally represented as VGAB. In a four wire wiring system, it is only necessary to connect the VGAB terminal of each alarm system in series to the VGAB terminal of another alarm system.
