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    Solid state relay SSR-120DA, 120A 3-32V DC to AC

    5 out of 5 based on 1 reviews | Write a review
    Low cost 120 Amp single phase solid state relay SSR-120DA , zero cross, input voltage 3-32V DC, load voltage 24-480V AC, LED indicator, excellent quality, high reliability and brand new.
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    Delivery date: 6-12 days


    120A 3-32V DC to AC solid state relay (SSR) features high structural strength, good impact resistance, and strong shock resistance. The SSR offers a reliable switching the commercial and industrial loads, such as computer peripheral interface device, printing machine, molding machine, food machine, packaging machine, and so on.

    • Built in RC absorption
    • Photoelectric isolation
    • SCR output
    • LED indicator for operation status
    • Removable protective cover for safety
    • Panel mount
    • Zero-crossing switch type


    Model ATO-SSR-DH120DA
    Input Control voltage range 3-32V DC
    Max. input current 12mA
    Must operate voltage 2.8V DC
    Must release voltage 1.5V DC
    Output Load voltage range 24-480V AC
    Peak voltage 800V AC
    Maximum load current 120A
    Maximum off-state leakage current 2mA
    Maximum off-state time 10mS
    Maximum on-state voltage drop 1.5V
    General Type DC to AC, single phase
    Dimension L – W – H (mm) 57.4х44.8х28
    Weight 135g
    Dielectric strength (input to output) 4000V
    Dielectric strength (input, output to the base) 2500V
    Operating temperature -20℃~ 80℃
    Mount Panel
    Certification CE


    1. When the load is a resistive load, the maximum load current of the selected SSR should be 2~3 times greater than the actual load current;
    2. When the load is an inductive load, the maximum load current of the selected SSR should be more than 7~8 times the actual load current.
    3. When the maximum load current is higher than 10A, a heat sink must be installed to the solid state relay, or the SSR relay should be mounted on a metal base plate with heat dissipation effect, and the thermal grease is applied between them.

    Dimension (Unit: mm)

    Single Phase SSR Dimensions

    Wiring Diagram

    Single Phase DC to AC SSR Wiring Diagram

    Tips: Construction of solid state relays

    Solid-state relays consist of three parts: the input circuit, isolation (coupling) and the output circuit.

    1. Input circuit
      According to different types of input voltage, the input circuit can be divided into DC input circuit, AC input circuit and AC-DC input circuit. Some input control circuits also have TTL / CMOS compatible, positive and negative logic control and anti-phase functions, etc. and can be easily connected with the TTL, MOS logic circuit. For the control signal with fixed control voltage, a resistive input circuit is used. The control current is guaranteed at 5mA or higher. For control signals with a large range of voltage (such as 3 ~ 32V), use a constant current circuit to ensure that the current works reliably at 5mA or higher over the entire voltage range.
    2. Isolation and coupling
      The way of isolation and coupling of solid state relays’ input and output circuit includes photo coupling and transformer coupling. Photo coupling usually uses the photodiode - phototransistor, photodiode - bidirectional light activated SCR, photovoltaic cells, to achieve isolation control of the control side and the load side; high-frequency transformer coupling is to use the self-excited high frequency signal generated by input control signal to form a drive signal through coupling to the secondary, rectification, and logic circuit process.
    3. Output circuit
      The power switch of SSR is directly connected to the power supply and load terminal to switch on and off the load power supply and mainly uses high power transistors (switch tube-Transistor), unidirectional SCRs (Thyristor or SCR), bilateral SCR (triac), metal-oxide -semiconductor field effect transistor (MOSFET), insulated gate bipolar transistor (IGBT). Solid state relays’ output circuits can also be divided into DC output circuit, AC output circuit and AC-DC output circuit and other forms. According to the load type, it can be divided into DC solid state relay and AC solid state relay. Bipolar devices or MOSFETs can be used for DC output and two SCRs or a triac for AC output. AC solid state relays can be divided into single-phase AC solid state relays and three-phase AC solid state relays. AC solid state relays, according to the timing of turn-on and turn-off, can be divided into random AC solid state relays and zero-crossing AC solid state relays.

    Solid state relay (SSR) is simple but widely used in the automation fields. Thus, it is not complex to wire a solid state relay. In this vedio, ATO takes a 40 Amp SSR (DC - AC) for example to show the wiring of a SSR and then switch on/off a motor with this SSR.

    Existing reviews of Solid state relay SSR-120DA, 120A 3-32V DC to AC
    Worked as it was supposed to
    This solid state relay has been working in my application controlling 24V AC, 120 amps with 10V DC control for some time now. No problems. Can't say how it would perform with other inputs, loads, or line voltage.
    From: Barrel | Date: 12/12/2022
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