How to connect a relay with dry contacts
Content
By the end of this article, you will be able to wire dry contact relays.
I will walk you through the process in detail in my guide below.
Dry contact relay: what is it?
Dry contacts are known as floating or floating contacts. A dry contact input is a simple type of electrical relay. It is described as a contact that receives power or voltage not from a switch, but from an external source.
In dry switching, contact currents less than a milliamp are sought. Also, since these connections are bare and unpowered, you must provide your own.
Dry contact relay: how to connect it?
When you're ready to install the relay, consider how far it is from the hub. To make sure they are installed correctly, you need to follow these procedures:
Step 1: Low voltage connections must be made with the power off to protect the entire system from short circuits.
Step 2: The wiring phase for all low voltage wiring is class 2. It would be better to run the low voltage wire in a different conduit than the mains voltage wiring.
Step 3: Pay attention to the location of all cables and tools so that the pins can be correctly positioned together.
Step 4: Connect the power supply to the relay terminal, then connect the relay to the desired circuit.
Please note that you should avoid installing the relay outdoors, on metal boxes and circuit breaker panels, and in certain locations that are below or above the temperature required for the relay.
Why is it called dry contact?
When the input changes, the relay required for dry contacts is activated or deactivated. This allows the dry contact input relay to determine whether the input switch is on or off.
Relay power can also be connected via a separate wire or a local power source near the dry contact input.
relay options
A relay is an electronically controlled switch that you will use with these contacts. They notify the contacts when it is necessary to open and close. Several types of relays can be used:
hybrid relay
In this case, both electromechanical and semiconductor capabilities are used. This requires the use of both, reducing their shortcomings. The key advantages of EMP are low closed-circuit voltage drop and no open-circuit power loss.
Thermal relay
Since the thermal relay cannot independently switch the primary circuit, it is paired with a magnetic contactor. If the temperature exceeds the limit, switching the contact from one state to another will help. They are mainly used for engine protection.
Reed relay
They contain two magnetic strips enclosed in a glass tube. The tongue can function as an armature and a connecting plate.
Electromagnetic relay
It can operate in both AC and DC modes. It consists of electrical, mechanical and magnetic components. A magnetic switch uses a magnet to create a magnetic field. The magnetic field is then used to open and close the switch and perform the mechanical action. (1)
Solid state relay
It is a solid-state analog of electromechanical relays capable of controlling electrical loads without the use of moving components.
Dry Contacts vs. Wet Contacts
If you're also wondering what wet contact is, the table below shows how they differ from each other:
| DRY CONTACT | WET CONTACT |
| Another source of energy is being used. | The same power supply powers it as the control circuit used to adjust the contact. |
| It is called the second set of relay circuit contacts. | This is known as the main contact group. |
| Used to ensure separation of devices. | It does not offer device isolation due to the same power supply. |
| The main advantage of dry contact input relays is that they provide complete isolation between both devices. | The main advantage of wet contact is that it makes troubleshooting easier due to the ease of connection and the same voltage level. (2) |
| Dry contact relays do not use mercury-wetted contacts. | Wet contacts refer to relays with contacts wetted with mercury. |
Take a look at some of our articles below.
- How to use a multimeter to check the voltage of live wires
- How to test a low voltage transformer
- What are the positive and negative wires in a USB cable
Recommendations
(1) magnetic components - https://link.springer.com/book/10.1007/978-94-015-4000-1
(2) voltage level - https://www.sciencedirect.com/topics/computer-science/supply-voltage-level
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