Dry Contact: Definition, Examples, & More

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In summary, dry contact refers to a type of relay or circuit where the contacts do not provide a source of voltage or current. This can be seen in examples such as a resistance furnace or industrial instruments with "dry contact" relays. Wet contact, on the other hand, involves the use of mercury wetted contacts. "Dry contact" can also be used to describe a transistor switch, such as an NPN transistor with open collector output.
  • #1
likephysics
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I am confused about dry contact. Does it mean dry contact vs wet contact as in mercury switch vs regular relay.
Any circuit examples.
Are transistor switches also referred to as dry contacts.
Is a NPN transistor with open collector output also referred to as dry contact?
 
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  • #2
Almost always means that the relay itself does not provide a source of voltage or current.
The contacts are simply two conductors coming into contact.

The equipment that is monitoring the dry contact must provide voltage/current to sense the state of the relay.
 
  • #3
I always used "dry contacts" basically as an interrupting circuit or relay output;

For example with a resistance furnace power always goes through a dry contact before the solid state relay. the dry contact functions as the over temp/alarm/permissive signal and the solid state as the control.

Many industrial instruments have "dry contact" relays in them which can be used to start/stop a completely separate circuit.
 
  • #4
Wet contact, to me, means mercury wetted contacts which are literally wet with mercury.

Dry contact either means no mercury or a little current that controls a larger contactor, depending on the context of its use.
 
  • #5


Dry contact refers to a type of electrical connection where there is no direct flow of current between two conductors. This means that the two conductors are not physically touching, but are still able to communicate a signal or trigger an action. This is commonly used in electronic circuits and devices to prevent damage or interference.

Some examples of dry contact include a mercury switch, where the connection is made when the mercury inside the switch makes contact with the two conductors, and a regular relay, where the connection is made when the relay is activated by an external signal.

Transistor switches can also be considered dry contacts, as they use a small amount of current to control a larger current flow. This allows for the two conductors to remain physically separated, while still being able to control the flow of electricity.

An NPN transistor with an open collector output can also be referred to as a dry contact, as the collector is not connected to any power source. This allows for the transistor to act as a switch, without the need for direct contact between the collector and the emitter.

Overall, dry contact is a useful concept in electronics and can be seen in various circuit designs. It is important to understand the difference between dry contact and wet contact, as wet contact involves a direct flow of current between conductors and can be more prone to damage or interference.
 

What is the definition of dry contact?

Dry contact refers to a type of electrical connection where no current is flowing between two conductors. This can also be known as a "no voltage" or "open" contact.

What are some examples of dry contacts?

Common examples of dry contacts include light switches, doorbells, and thermostats. These devices use a dry contact to complete a circuit and activate a function without any current passing through the contacts.

How do dry contacts differ from wet contacts?

Dry contacts are characterized by the absence of current flow, while wet contacts involve the flow of current between two conductors. Wet contacts are typically used for high voltage applications, while dry contacts are used for low voltage applications.

What are the benefits of using dry contacts?

Dry contacts offer a number of benefits, including increased safety, as there is no risk of electric shock or fire. They also have a longer lifespan and are less prone to wear and tear compared to wet contacts.

How are dry contacts tested?

Dry contacts can be tested using a multimeter or a continuity tester. These tools can measure the resistance between the two conductors to determine if the contact is open or closed. A closed contact will have low resistance, while an open contact will have infinite resistance.

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