Advantages and disadvantages of instruments powered by 220V and 24V?
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During the selection process, many instruments do not require power supply, while others do. The power supplies available are 220V and 24V – what is the difference between these?
It depends on the actual conditions on site. For applications where high explosion-proof requirements apply, it’s better to use 24V power supply, as it constitutes a safe voltage level. Moreover, working with 220V requires a electrician’s license, as it involves certain risks; the equipment specifications also need to be taken into consideration
This post was last edited by qugd on 2018-8-7 08:27. Which instruments do not require power? Are you referring to the pressure gauge temperature meter on site? There are no electrical components or circuits in the instrument, so it certainly does not require power supply. There are electrical components and circuits; without power supply, the instruments will not function. As for the power supply requirements, they are determined by taking into account factors such as the power consumption of the instrument itself, the requirements for the output signal, and safety considerations.
In areas with explosion hazards, the wiring boxes for 220V.AC-powered instruments must be of flameproof type, and their covers must not be opened for maintenance while they are still under voltage. A 24V.DC power supply can have its energy limited by a power safety barrier; some meters are already two-wire systems, and by adding a safety barrier, they can operate in intrinsically safe mode, allowing for maintenance by opening the cover at any time. Convenient and safe.
24V can be used in a redundant configuration, while 220V is not suitable for this purpose. 220V allows for longer transmission distances, whereas 24V has a shorter range (although thicker wires can be used)
Using 220V for powering the instruments is a last resort; for example, older radars required heating, which led to high power consumption, and 24V was not sufficient to meet this demand. The same applies to electromagnetic flowmeters – they require 220V for proper operation and accurate sensing； Thanks to advances in measurement technology and reduced power consumption of components, 24V is now sufficient to meet the requirements; even some instruments such as mass flow meters can be powered via a feedback loop. In the future, instruments might not even require cables anymore: lol
Some instruments nowadays can already be used wirelessly.
Do thermoresistors and thermocouples require power supply? Do digital instruments with dry contacts require power supply?
This post was last edited by qugd on 2018-8-7 08:29. Have you read the third line of my post? Idiot. You should be familiar with the definition and concept of dry contacts. Trash.
Generally, it’s better to use a two-wire system whenever possible; avoid using an additional power supply, as 24-volt power sources can still generate sparks.
The difference is that one can kill a person with electricity, while the other cannot.