Potential Free Contacts?

A 'contact' is someone you know. 'Potential free' means having no potential.

So a potential free contact would be like a brother-in-law.

Naw, it would be an electrical contact that has no energy, no potential. Wait a minute, that is a brother-in -law.

Or maybe...

The electrical contacts on a relay are potential free until you connect a wire with a voltage on it to the contact. Another example is typically a flow or pressure switch. The contacts are like the contacts of a relay, there is no voltage connected to either from inside the switch.

This style is also referred to as 'dry' contacts. Wetted contacts have voltage applied to at least one of the contacts. (and yes, there are also mercury wetted contacts where the mercury carries current)

The use of potential free contacts allows
- connection to a device that sources its own voltage.
- connection of multiple devices in series and/or parallel for relay logic control

Open collector, PNP or NPN devices are not potential free or dry contact devices.

Here is a good explanation by this guy "yohead40"

"open or close contact controlled by the coil, by energizing the coil the magnetic contact will close and when you de-energize the coil the contact will open. when its open is free contact."

In IEC parlance these may be appropriate....

• Potential free
• Not potential free

"Potential Free Contact" is a spare contact from your control relay that is located in this control panel, where the source or signal that terminated to this "potential free contact" or used this relay contact is NOT coming from the same control panel. The signal or the source may come from other control panel that need this potential free contact for signaling or for process