Good afternoon, I want to continue the story about the T2 relay.
I had such an idea, even at the testing stage, but due to the fact that the relay at a voltage of 24 volts (safe voltage) is not controlled by external switches, I stopped the research.
Now I will tell you about a method of controlling the water level in the tank using T2 and a ready-made optocoupler->relay board (HW-373, 2-Relay Module, SRD-12VDC-SL-C)
Task statement.
1- make a safe control system (using safe voltages for people);
2-use of improvised materials as control sensors;
3-connect to the power part of the water pump control;
4-organize automation to control the water level.
Description of the system.
Using the optocoupler-relay board, we will make a water level sensor (safe for people, 12 volts). Channel 1 (lower level), channel 2 (upper level), body channel (-12 volts) are connected to the tank. When the water level fills (drains) channel (1,2) with body (-12 volts) the corresponding relay (1 or 2) will be triggered. We use dry contacts of the optocoupler-relay to control T2 (Com, S1, S2). Relay T2 (L2) works to turn on (off) the water pump (if the pump power allows working with T2), or the contactor that controls the pump (I recommend this option). Next, the principle of operation, you understand, if channel 1 is dry then the pump is On, if channel 2 is wet then the pump is Off.
Figure 11.
Emergency shutdown of the pump in case of failure of the optocoupler sensors.
For emergency shutdown of the pump, I used my rationalization associated with the connection to the power outputs (L1 and L2). I made blanking (a term in electrical engineering for connecting relay contacts that blocks one contact with another).
Explanation - we connect the contact from the LIN point to the L1 point, this gives us the opportunity to control the L2 contact using L1. That is, if L2 is on and L1 is off, then voltage will not be supplied to the pump (in our example, a lamp).
Figure 1, 2.
We will receive the EMERGENCY signal from the leak sensor, in which pieces of wire are connected to the contacts (hexagonal screws). These pieces of wire are placed at the height of the emergency water overflow pipe (this point is above the upper water level sensor).
The “flooded” signal from the Aqara sensor turns off the L1 contact, which in turn de-energizes the water pump (in our case, a lamp), and gives a push message “PUMP BREAKDOWN!!!”.
The system can only be restarted after an emergency manually from the application (after clarifying the cause of the automation malfunction).
Devices for implementing the task.
1 - Aqara T2 relay;
2 - Aqara leak sensor
3 - ready-made board, optocoupler-relay for two channels (Songle SRD-12VDC-SL-C), freely available;
4 - 12 volt power supply (for clarity, I use a 12 volt battery);
5-pin iron or pieces of solid wire.
Solution to the problem.
We power the optocoupler board from 12 volts.
Figure 3.
Mounting the optocoupler board and T2.
- Connect the normally closed contact of the optocoupler that will control the On pump (lower level) to S1.
Note - for stable operation of the On pump at the lower level (researched by me), you must use a normally closed contact. With this connection, the automation logic (in wireless T2 mode) works perfectly. - Connect the normally open contacts of the optocoupler relay that will control the Off pump (upper level) to S2. as shown in the figure.
Figure 4.
Mounting the optocoupler board to the tank.
-The common wire (for the tank) can be connected to the tank (if the tank is iron) or to the pin in the water (it will have a potential of -12 volts).
-Connect channel 1 of the optocoupler to the lower water level sensor and channel 2 to the upper water level sensor.
Figure 5.
We supply 220 volts to the relay T2. We supply the L2 contact to the pump load (I have a lamp connected for clarity of work).
Creating automation.
We transfer T2 to the mode of a wireless button and logic elements.
Figure 6.7.
Explanation of the automation logic.
We will use the S1 signal to start the pump. In the connection, we chose normally closed contacts so that the “no water” signal always passes. So that you understand, the logic element operates according to the principle of one through two. Example - if the contact is closed (and does not release), the logic is triggered, then (after some time) the contact is broken, the logic does not work.
In our case, the pin (On pump (lower level)) will be wet and the relay is open (there is a contact through the water of the optocoupler and the common wire -12 volts). Only when the water level drops, the optocoupler will turn off and a signal will go from the normally closed contact to S1.
The second feature of the automation is that the S1 channel controls the L2 contact.
To protect the pump from running dry (pump operation without water), I give a delay of 15 minutes. My time is calculated experimentally and is based on the time of pumping a full tank of water. Everyone has their own tank volume.
The first automation is “On water pump”.
IF
- S1
THEN - On CHANNEL 2
- delay 15 minutes
- Off CHANNEL 2
Figure 8.
To turn off the pump, the same thing, only with normally open contacts on S2. The water level will rise, the optocoupler will turn on and a signal will go from the closed contact to S2 (everything is the opposite as in S1). The pump will go into Off mode
Second automation “Off water pump”.
IF
- S2
THEN - Off CHANNEL 2
Figure 9.
Third automation “Alarm vater pomn!!!”
IF
- leakage
THEN - Off L1
- puch message.
Figure 10.
This automation has been working for me for more than two years. I additionally created a scenario that can turn on the pump for water pumping at any time.
I have not had an emergency shutdown of the system due to water overflow even once in two years of operating the system.
Video of the system in water pumping mode.
VIDEO 1
Video of the system in an EMERGENCY (water overflow).
VIDEO 2
Note - in the video, the switches on the phone do not switch synchronously with the rotation, in the room where the video was shot, there is poor Internet coverage, the main indicator of operation is the lamp.
This concludes my story about such a universal T2 relay.
If anyone wants to read how to use only leak sensors to control the water level, comment here. I am ready to make a new extended topic on this issue.
Thank you for viewing my topic.
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