What is Dry Contact?
Dry contacts are also called voltage-free contacts or potential-free contacts**.** It is defined as a contact in which that doesn’t provide power/voltage from the switch, but is provided from an external source.
Dry switching looks for contact currents of less than one milliampere. Because these connectors are bare and without energy, you must provide your own power.
Why do they call Dry Contact?
When the input changes, the relay required for the dry contact will be energized or de-energized. This helps the dry contact know whether the input switch is on or off.
The voltage that powers the relay can be connected using a separate wire, or you can use a local power supply near the relay.
Now that you understand dry contacts, there are still wet contacts to understand.
How to wire a dry contact relay?
Any relays you need to put in have to be accomplished professionally with the aid of using an electrician. When you’re equipped to put in the relay, you have to think about the space it’s far from the hub and the prevalence of different items which could intrude with the signal.
There are steps to make certain that they may be effectively installed place:
Step 1: All low-voltage wiring have to be accomplished with the electricity grew to become off to the good judgment board in order to guard the entirety from any shorts.
Step 2: Class 2 is the wiring stage for all low-voltage wiring. The low-voltage wiring have to run in a separate conduit from line-voltage wiring.
Step 3: Take be aware of all your wiring and tool places in order that the touch may be nicely positioned together.
Step 4: Connect the electricity deliver to the relay terminal after which the relay touch to the wished circuit with wires.
Try now no longer to put in a relay withinside the following places:
- On the outdoor of the premises
- Inside metallic junction containers and electric breaker panels
- In sure regions that move under or above the temperature and humidity wished for the relay
- Be certain to live secure and comply with protection policies with regards to putting in electric gadgets to your home, business, or elsewhere.
Once you’ve got an concept of a way to cord your contacts, sure gadgets require both dry or moist contacts.
Examples of Dry Contact
- Fire alarms
- Control relays
What is Wet Contact ?
A wet contact is a contact that is powered by the same power source used by the control circuit to change the contact. This can be referred to as the primary contact sets.
Examples of Wet Contact
- CO2 Sensors
- Humidity sensors
- Flow sensors
- Pressure sensors
Dry Contact VS Wet Contact
The following table discusses the difference between dry contact and wet contact.
|Dry Contact||Wet Contact|
|Power is being supplied by another source||Powered by the same power source used by the control circuit to change the contact.|
|It can be called the second set of contacts in the relay circuit.||This can be referred as the primary set of contacts.|
|Used to provide isolation between devices||It doesn’t provide isolation between devices due to use of same power source|
|It is also known as Passive contacts||Wet contact is also called as Active or Hot Contacts|
|Dry contacts suggest a relay that doesn’t use mercury-wetted contacts||Wet contacts suggest a relay that uses mercury-wetted contacts|
|Advantage: It provide complete isolation to devices||Advantages: Because the wiring is simple and the voltage level is the same, it makes troubleshooting easy.|