40A Three Phase Solid State Relay

In everyday life, solid-state relays are increasingly taking their place; they are simply not replaceable when the load is turned on and off very often and ordinary electromagnetic relays simply cannot withstand mechanical loads, wear out and break. In addition, these annoying clicks when turning the load on and off clearly favor the use of solid-state relays, which are absolutely silent.

However, the price of these new relays, especially three-phase ones, makes us think about the feasibility of their use. In this case, making such a relay yourself can help, and this site will help you with this. Making a three-phase 40 ampere relay with your own hands will cost you a maximum of 500 rubles, even if you buy all the parts, while a factory one costs several thousand. It's worth thinking about. Right?

The factory relay, if parts of the internal device are damaged, cannot be repaired and requires complete replacement.A homemade relay, made with your own hands, will serve you for many years, because you will thoroughly know its structure, and if any of its parts burn out, you can change them without any problems and continue using this very useful device.

So let's get started.

Solid state relay circuit

Details

We will need it for work.

  • S1 – Any switch or toggle switch.
  • F1 – fuse 0.25 – 0.5 Ampere.
  • C1 – 0.068 uF 630 Volts.
  • R1 – 470 kOhm.
  • R2 – 100 Ohm.
  • VDS1 – Rectifier bridge 1 Ampere 600 – 1000 Volts or separate diodes.
  • D1 – zener diode 20 Volt 0.5 Watt.
  • C2 – 10 uF 25 Volts.
  • HL4 – any signal Light-emitting diode.
  • MOC3063 – 3 pieces.
  • R3, 7, 11 at 330 Ohm 0.5 Watt.
  • C3, 5, 7 – 2.7 nF each 50 Volts. For current up to 10 Amps per phase. If you are planning a higher load, then you need to set it to 3.3 nF.
  • R4, 8, 12 at 470 Ohm 2 Watts. For current up to 10 Amps per phase. If you are planning a higher load, then you need to install 330 Ohm 2 Watts.
  • T1, 2, 3 – triacs VTA41-600 – 3 pieces.
  • VD1, 2, 3, 4, 5, 6 – protective TVS diodes type 1.5 KE300CA.
  • R5, 9, 13 – 47 Ohm 5 Watt each. For current up to 10 Amps per phase. If you are planning a higher load, then you need to install 27 Ohm 5 Watt.
  • C4, 6, 8 – 0.047 uF each 630 Volts. For current up to 10 Amps per phase. If you are planning a higher load, then you need to install 0.1 uF 630 Volts.
  • D2, 3, 4 – any diodes with a voltage of at least 600 Volts. For example 1N4007.
  • HL1, 2, 3 – any signal LEDs.
  • R6, 10, 14 – 470 kOhm each.
  • Breadboard – 2 pieces.
  • Thermally conductive paste.

Manufacturing of three-phase solid state relay

It is best to start collecting parts from the body of the future device. Circuit breaker boxes, which are sold in electrical supply stores, are well suited for this purpose.The price is quite affordable and depends on the size of the box.

The most important part of the future relay is the radiator for cooling the triacs. The more comfortable the temperature for the triacs during operation, the longer they will “live”. In a word, the radiator should be as large as possible (within reasonable limits). If the body of the future relay is metal, then the radiator plate can be tightly screwed to its back wall, and then the entire case will be a large radiator.

VTA-41 triacs can be screwed without insulators, directly to the radiator, since their terminals have no electrical contact with the substrate. For other triacs, it is necessary to check the data.

Before installing the circuit parts on the board, I tested the operation of the optocouplers, the photo shows how. Of the 20 pieces of MOS3063 purchased in China, 3 turned out to be defective. So be careful.

We begin the installation by marking and installing the triacs, and then the remaining parts.

We solder. We solder the wires with a larger diameter (depending on the load).

We very carefully remove excess copper contact pads on the breadboard between the high-voltage wires (as in the photographs) to avoid short circuits. 380 Volts is a very high voltage and life-threatening.

We attach the leads of the parts to the following board.

We install sockets for optocouplers. If an optocoupler burns out during operation, it can be replaced in a couple of seconds.

Installing control parts.

We test the operation of optocouplers.

We alternately apply 220 Volts to each phase for testing.

We connect the device to each phase in turn and check the opening of the triac when the control voltage is turned on. 4.2 mOhm – triac is closed.

The triac is open.

After making sure that the relay is working, fill the places on the board where there is high voltage with hot melt glue.

Lubricate the triacs with heat-conducting paste and attach them to the radiator. The breadboard is mounted on insulating washers.

We fix the device in the case and close it. The three-phase solid state relay is ready for use.

Watch the video

Watch the video for testing the relay in operation.

come back
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Comments (6)
  1. Bald
    #1 Bald Guests 29 July 2018 20:40
    1
    Great, but the title doesn't quite seem to fit. Phase-by-phase control, phase-by-phase solid state relays..
    1. Krazy_killer
      #2 Krazy_killer Guests 16 January 2019 21:56
      0
      Why phase? and how is this so different?
      At first I was also confused by the thick line that amounts to a zero bus. but this is just an example of switching on, in fact, erase the “load” and the communication line to zero. and connect, for example, a motor or a three-phase transformer.
      I’m thinking about assembling this for a powerful air conditioner, but before equipping it with a phase control unit, a low-current relay for a “normally closed contact” (
  2. Romanov Sergey
    #3 Romanov Sergey Guests July 14, 2019 08:31
    6
    Thank you.The device can actually be useful in certain cases. Neat and thorough installation. At the same time, I would like to draw your attention, colleague, to certain points. The use of low-melting hot melt adhesive to insulate bare network conductors close to a potentially heating radiator is questionable. The placement of triacs on such a huge radiator is far from optimal; only the upper part will work. The proposed plastic case does not have special ventilation holes. The location of the switch under the transparent cover (the control that will be used frequently) is inconvenient. Moreover, it is located quite dangerously - next to there is an opening with elements galvanically connected to the network. Sooner or later, they will hit it with a finger.
    Check out my version of a homemade single-phase solid-state relay complete with a PID temperature controller
  3. Guest Alexey
    #4 Guest Alexey Guests 12 February 2020 20:15
    1
    But if you add 2 more triacs with galvanic isolation, can you reverse the motor? Will the other triacs not open?
  4. Oleg
    #5 Oleg Guests 6 June 2021 23:18
    0
    The purpose of suppressors is not clear... Usually varistors are installed in such circuits, this is enough. In the above embodiment, the suppressor will transmit impulse noise in parallel to the closed triac, i.e. directly into the load.

    Another IMHO jamb is the output indication: LEDs will light up when the switch is closed, passing some current, again, into the load, which according to Z should be de-energized...
  5. Oleg
    #6 Oleg Guests February 9, 2023 11:37
    0
    Just out of interest, a question for you: Why... to complicate the circuit so much? a bunch of parts - low-power optosimistors to high-power triacs and a bunch of different additional parts..Are you kidding? throw out... MOC3063 and everything that comes after them and replace them with powerful opto-relays of 30A, 40A, or at least 200A. Voila - enjoy life)))