Difference between passive contacts and active contacts
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This post was last edited by jacob451 on 2010-10-26 at 13:55. Could you explain how passive contacts and active contacts are defined? Examples would be helpful Thank you
This post was last edited by Hardmen on 2010-10-23 07:53. Contacts that are normally open, such as those in contactors and relays, and which must be powered in order to function, are known as passive contacts. Contacts like those generated by PLCs, on the other hand, are called active contacts
As I understand it, instruments that have their own power supply and do not require power from a DCS are active instruments; they are usually of the 4-wire type, such as electromagnetic flowmeters. The instrument does not have its own power supply; those that require power from the DCS are passive devices, usually operating on a two-wire system. I’m not sure if this understanding is correct.
As I understand it, an active contact is one that has an external power supply, while a passive contact is one that lacks an external power supply and serves to establish a connection.
My understanding is that when the contacts of this device output power, it is called active output. They are simply called passive contacts when they require an external power supply; I’m not sure if this understanding is correct. It seems that the output contacts of the Siemens 200 series are also passive contacts, meaning they need an external power supply to function
Simply put, a four-wire system is passive, while a two-wire system is active!
Correction: Not all PLC outputs are active!
The difference between active and passive lies in whether the system’s circuit is required to supply power to the instrument; if it is needed, then it is active, whereas if it isn’t needed, then it is passive.
Active and passive nodes. Definition of passive node: Passive switch； Has two states: closed and open ； There is no polarity between the 2 nodes, so they can be swapped ； Common signals from passive nodes include: (1) various switches such as limit switches, travel switches, foot switches, rotary switches, temperature switches, level switches, etc ； (2) Various buttons ； (3) Outputs from various sensors, such as those used in environmental condition monitoring: water intrusion sensors, fire alarm sensors, glass breakage sensors, vibration sensors, smoke sensors, and condensation sensors ； (4) Output of relays and reed switches ； The definition of an active node is: an active switch ； It has two states: powered and unpowered ； There is polarity between the two contacts; they cannot be connected in reverse ； The most common active node signal is: (1) Connect the above-mentioned dry node signal to a power supply, and then connect the other pole of the power supply as the output; this constitutes the active node signal ； In industrial control, the common voltage range for wet nodes is DC0 to 30V, with DC24V being the more standard value ； The AC110～220V output can also be an active node, although this is done less frequently.
The post has been posted; it’s up to professionals to come to a correct conclusion. The answers to the questions in this post are quite vague; I think nothing of what was said is accurate. I hope someone who is an expert in this field can explain it – this isn’t a difficult question at all. Why do everyone have to guess? Guess who’s right? I wonder too; after seeing the replies to that post, I don’t dare to follow it.
I completely agree with what was said above. I’ve looked up a lot of information, but it all seems rather vague