Basic definition of associated devices
Electrical equipment that contains energy limiting circuits and non energy limiting circuits, and is structurally designed such that non energy limiting circuits cannot have adverse effects on energy limiting circuits.
The basic function of associated devices
Associated devices, as energy limiting devices, can effectively protect on-site equipment in hazardous areas. Under normal working conditions, they can ensure the system operates properly, while under fault conditions, they can limit the voltage and current reaching the hazardous area.
Classification of associated devices
Common associated devices in practical applications include safety barriers, which are further divided into Zener safety barriers and isolation safety barriers. And then there isIntrinsic safetyPower Supply.
The associated device can be any of the following two:
（1）HavingGB/T 3836. 1-2021Another explosion-proof type specified, which can be used for electrical equipment in corresponding explosive gas environments;
（2）Not adoptedExplosion proof typeProtect electrical equipment that cannot be used in explosive gas environments. For example, if a recorder is not in an explosive gas environment, but it is connected to a thermocouple in an explosive gas environment, only the input circuit of the recorder has energy limiting characteristics.
Simply put, the associated device is intended to be used in a safe location and to provide power or communicate with intrinsically safe devices in hazardous areas without affecting their intrinsic safety parameters. So the output circuit of the associated device must be an intrinsic safety circuit. If it is to be used in a hazardous location, the associated equipment must be protected with another explosion-proof type, such as a flameproof enclosure.
It is worth noting that the associated devices do not have temperature groups, which is commonExplosion proof markAs follows:
［Ex ia Ga］ⅡC
Intrinsic safety electrical parameters:Uo、Io、Po、Co、Lo；
When associated with other devices, the selection generally follows the following principles:
Ui≥Uo，Ii≥Io，Pi≥Po，Ci≤Co，Li≤Lo；
Safety barriers are mainly installed in safe places and contain devices with intrinsic safety circuits and non intrinsic safety circuits. The energy sent to the on-site intrinsic safety circuit is limited by current and voltage limiting circuits in the circuit, thereby preventing hazardous energy from non intrinsic safety circuits from entering the intrinsic safety circuit.
Application example: Explosion proof power supply device supplies power to external intrinsic safety equipment; The collector collects intrinsic safety equipment signals from explosion-proof areas
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