What is potential free contact ? Is there such a thing?
A contact in a electrical or electronic circuit allows or blocks passage of power or electricity through them .This means they are subject to some voltage if they are used in such circuits .Then how some contacts specified as volt free?
What is the meaning?
Potential free contact/Dry contact/volt free contact
Yes ….Every contacts are subjected to power when we used them in powered circuits .That is true .But the classification of contacts as volt free and wet contact is another thing .Such classification is based on their default condition .Means no external power is connected to it .If a device or system provides a contact without any voltage in it .It is called potential free contact or volt free contact .See figure below .
They are simply contacts with no potential .For example relay contacts .They are also called Dry contacts or Vollt free contact
If a system or device gives a switched output or contacts without any Voltage it is termed as potential free contact .It doesn’t mean no current or power is not fed through such contacts . Power is indeed required .But it is delivered from external source
A device such as relay coil ,on actuation make a contact close .It is a volt free contact or dry contact . Because it is not subjected to any power or voltage . The contact is not connected to any internal power circuit .So if a device provides a switched output or contact without any potential ,then the contact is called a potential free contact .And to make use of this contact external power is required .
The above image is a electromagnetic relay .It provides normally open and close contacts .On actuation,these contacts make or break the circuit .By default these contacts are potential free .Means no power is fed to them internally .
Wet contact
Wet contacts?
Yes it means it provides a powered contact .see below figure
.The device has a switched output and it is powered through its internal power circuit .So to a external system this output is a powered contact or wet contact. To operate the circuit it may not need a external power supply .see below figures .
A Control system provides a volt free contacts .what does this mean?
It means we only get a contact without any power And we should use external power for making use of this contact.
And a control panel providing wet contact means we are getting a switched power .
