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    Solid state relay SSR-120AA, 120A 70-280V AC to AC

    Affordable price single phase solid state relay SSR-120AA, load current rating up to 120A, zero cross switching type, AC control AC,70-280V AC input voltage, 24-480V AC load voltage, brand new, high quality and long life time.
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    Delivery date: 6-12 days


    120A 70-280V AC to 24-480V 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-DH120AA
    Input Control voltage range 70-280V AC
    Max. input current 15mA
    Must operate voltage 70V AC
    Must release voltage 50V AC
    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 AC 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 AC to AC SSR Wiring

    Tips: Overvoltage protection for solid state relays

    Transient voltage disturbance is one of the main causes of damage to electronic circuits and equipment. In the process of using solid state relays, instantaneous voltage damage to the solid state relays often occurs.
    Common overvoltage protection methods include: RC snubber circuits, metal oxide varistors (MOVs), and built-in transient voltage suppressors (TVS).

    1. The RC snubber circuit absorbs and suppresses the momentary voltage applied to the solid state relay and reduces the rise rate of voltage index (dv/dt).
    2. MOVs are bipolar protection elements that absorb excessive transient voltages. However, with the energy absorption at each time, the performance of MOVs changes, the voltage level decreases and eventually the risk of overheating occurs due to unbearable supply voltage.
    3. TVS (Transient Voltage Suppressors) is efficient silicon PN junction protection device, a new product developed based on the voltage-regulator tube technology. Subjected to a transient high-energy impact at both ends of the TVS tube, it can turn the high impedance at both ends into a low impedance at very high speeds (response time is typically less than a few nS) while absorbing a large current, clamping the voltage between the two poles to a safe value, thus ensuring that the circuit components behind are protected from the impact of transient high energy.

    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.

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