How to control remotely an electric lock with Ajax Relay


The relay should be only installed by a qualified electrician! Regardless of the type of the electrical circuit in which the device is installed.

Relay can be used to block access to the room by automatically locking the electric lock when the security system is armed. TThe user can also manage the power supply of the electric lock manually via the Ajax app, Button press, or automatically, using a scenario.

The relays are used to open and close electrical circuits and can be used to control the power supply to electrical appliances. Ajax Relay is a low-current remote control relay with a potential-free “dry contact”.

Which electric lock should you choose

We will consider connecting the most popular types of electric locks in the article: electromechanical and electromagnetic.

Electromechanical locks include pulse and bistable ones, electromagnetic — only bistable.


  • Pulse locks — open and close when a pulse is applied.
  • Bistable locks — open and close in the presence or absence of direct current.

Electromechanical locks

ajax electric lock

This type of lock is equipped with a small DC electric motor that controls the bolt when an electrical signal is applied.

With respect to fail-safety, the locks are divided into two types:

  • Normally closed — unlocking occurs when an electrical signal is applied.

    Such locks are forbidden to use along escape routes!

  • Normally open — the lock opens when there is no voltage. Such locks are used to build emergency exits and other passages where unimpeded opening of the door is necessary when the power is turned off.

Electromagnetic locks

ajax electric lock

They consist of a unit with an electromagnet and a strike plate made of metal. The principle of the lock’s operation is based on magnetic attraction. The unit with an electromagnet is mounted on the door frame, and the strike plate is mounted on the door. When power is applied, the lock attracts and holds the strike plate locking the door. In the absence of the power supply, the electromagnetic lock opens.

Backup power

It is recommended to supply any electric lock with backup power:

  • In the case of a normally closed lock, it will allow you to open the door when there is a loss of electricity in order to enter the room or leave it urgently
  • Electromagnetic and normally open electromechanical lock without backup power does not prevent access to the room.

Take care in advance of the feasibility of opening the door in the case of emergency! For example, by connecting a button to enable emergency opening of the lock.

Schematic diagram of connecting the Relay to a 12/24-volt electric lock

ajax relay

In order to connect according to the schematic diagram, you must have an external 12/24 V power source!

  1. Connect the power supply to the power terminals of the relay.
  2. Connect the power supply “+” to one of the relay contact terminals, and “+” of the electric lock to the other contact terminal of the relay.
  3. Connect “–” of the electric lock to the “–” of the power source.

This connection scheme enables the Relay to control the power supply to the electric lock.

Electromagnetic and bistable electromechanical lock control

Relay Setup

  1. Go to the Devices tab .
  2. Enter the Relay menu, go to Settings   and select Bistable operation mode, and also set Initial state of contact terminals: Normally disconnected.

Manual control of the electric lock

Click the switch in the Relay line — the state of the relay contact terminals will become the opposite.

ajax mobile applications

When the relay contact terminals are closed, the electric lock is supplied with power remaining in the closed state. Upon disconnection, the lock is left without power supply and it is opened.

Pulse lock control

Relay Setup

  1. Go to the Devices tab .
  2. Enter the Relay menu, go to Settings   and select Pulse mode, and also set the Pulse duration in the range of 0.5~15 seconds (the value will be indicated in the electric lock documentation).

Manual control of the electric lock

Click on the pulse icon in the Relay line to trigger a pulse and change the lock status

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Automatic power supply management of the electric lock

Create a scenario to activate one or several electric locks automatically when arming/disarming the security system, by alarm or Button press, as well as according to a schedule.

A scenario can be created in the Relay settings: Devices RelaySettings Scenarios.

Learn more: How to create and configure a scenario in the Ajax security system.

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