potential free contact

Can you please explain a little more about your application?

Potentail free contact means there is voltage available on this pair of contacts.the contacts may be NO or NC.

Supposing the contact is already used in some other circuit with voltage of 24 V dc, then this contact is with potential of 24 V.

In case you wanted to use contact this same contact on some other circuit of voltage 12 V DC, then the device to be connected will have 24 V and damage the device. Therefore contacts with potential free contacts are preferred for different circuits.

Trust this is clear

I am totally agree with you but i would like to add that while mentioning the potential free contact you need to specify the rating of the contact & they should be used within specified contact rating of contact.

Sorry Mr Ramvinod
But Your Reply Is Incorrect. The Correct Explanation Is Stated Below,,, A Contact Can Only Be Potential Free If Its Having No Voltage :D
"" Potential free contacts (also called "dry contacts") are simply contacts which are physically operated with the main device, but not electrically connected to it. For example a motor contactor often has auxiliary contacts that are operated by the main coil and open and close at the same time as the main contacts but are not used for control of the motor starter. If they are connected to an outside circuit to indicate the status of the starter without being powered by the motor supply they would be considered potential free contacts.
These type also called Signal-Contacts.

In case of relays and switches if the common/pole is connected internally to a given potential like a 110V phase etc., the contact is not POTENTIAL FREE but if both the common and the normall open (and at time also the normally closed) contacts are presented to the user for connecting in his system as he pleases,the contact is said to be "potential-free".

Basically, potential free contacts mean that the switch or relay contacts have no connection to any thing else which may have a voltage on it...

So you can wire to the contacts without worrying about shorting to earth perhaps?!

In other words the contacts are isolated from any other voltage source.

John.

There is a slang term "dry contact" for it as well.

Now that I understand. Thanks.

Hi,

I would like to tell you that potential free contact means the contact (NO or NC) that can be used to any type of potential with any values. I mean to say potential free contact if used in circitry of 110VAC then same contact can be used in 110VDC circuit also or if it is used in 110VAC & then same contact can be used for 230VAC also or 24VDC also or 110VDC also. BUT PLEASE TAKE CARE THE FOLLOWING.......

While specifying the potentail freen contact you need to see the current rating of the contact i mean to say if you are using contact (rated for 2amp)for 110VAC@2amp then the same contact can be used for 230VAc,110VDC,24VDC or any type of other voltge provided the current rating should be within 2 Amp only. if contact rating is 2Amp and if you want to use in circuitry having current rating is more then 2Amp then it will be damage. So at the time of specifying the potentail free contact for relays or switch then you should mention the require current rating of the contact also.

I hope above is clear.

I agree with you about rating.

In this context the guest has asked explanation only about potential free contact.therefore I have limited the explanation.

Further to add about the rating of the contacts, one has to see both current rating as well as voltage rating of the contact
also ac/dc ratings.for example the contact may be rated for 6 amps ,110 V AC, but it does not mean you can use the relay contact for 110 V DC for 6 amps or 6 amps ,230 V AC.Get the rating from data sheet for different voltages of AC/DC .

Thanks for comments

THIS IS A VERY GOOD EXPLANATION

I know this is an old post, but are you talk8ng about a ‘potential free signal’?

I used this quiet a bit for integrating different different control platforms, such as Allen Bradley and Siemens for example.

It’s for communicating between platforms…

let’s a the AB platform is the main platform on a process line, and you have an additional upgrade using Siemens. It’s basically controls the signals between the two (2) using relays.

you start the process up using AB, AB be sends a signal to the Siemens relay that they are ready to start. Siemens checks it’s process if all’s good, it sends a signal back to an AB relay where AB reads it and then sends the start signal back to Siemens to start, all done through relays.