Best Seller SSR-40AA AC to AC Solid State Relay - 2 Pack
Two SSR-40AA solid state relays with clear protective covers and blue labels.
SSR-40AA solid state relay wiring diagram showing AC power supply and load connections.
Single SSR-40AA solid state relay showing copper terminal outputs and heat-dissipating metal back plate.
Two SSR-40AA solid state relays shown from front and top angles with technical specifications on the label.
SSR-40AA solid state relay collage showing industrial, renewable energy, and electronic circuit board applications.
SSR-40AA solid state relay unit shown in a close-up product view with installation text overlay.
Couple relaxing on a sofa using a remote to control a wall-mounted air conditioner.
Two SSR-40AA solid state relays with clear protective covers and blue labels.
SSR-40AA solid state relay wiring diagram showing AC power supply and load connections.
Single SSR-40AA solid state relay showing copper terminal outputs and heat-dissipating metal back plate.
Two SSR-40AA solid state relays shown from front and top angles with technical specifications on the label.
SSR-40AA solid state relay collage showing industrial, renewable energy, and electronic circuit board applications.
SSR-40AA solid state relay unit shown in a close-up product view with installation text overlay.
Couple relaxing on a sofa using a remote to control a wall-mounted air conditioner.

SSR-40AA AC to AC Solid State Relay - 2 Pack

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$17.59
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$17.59
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SSR-40AA Solid State Relay

Key Features

  • Model: SSR-40AA
  • Type: Single Phase AC-to-AC Solid State Relay
  • Load Current: 40A
  • Input Voltage Range: 70-280V AC
  • Output Voltage Range: 24-480V AC
  • Switching Method: Zero-Crossing
  • Features a built-in LED status indicator
  • Designed with a metal base plate for thermal management

Replaces / Cross-Reference Part Numbers

  • SSR-40AA
  • SSR 40AA

Compatibility & Fitment

  • General-purpose component for applications requiring AC load switching.
  • Commonly used in temperature control systems (PID), industrial automation, heating elements, lighting controls, and other machinery.
  • Designed for use with resistive loads.
  • Ensure your application's voltage and current requirements fall within this relay's specified operating range.

When to Replace

  • The connected load does not turn on when control voltage is applied.
  • The connected load remains on permanently, even with no control voltage.
  • Operation is intermittent or unreliable.
  • Visible signs of overheating, charring, or physical damage to the relay casing.

Installation Tips

  • A heat sink is required for loads exceeding 10A to prevent overheating.
  • Apply a thin layer of thermal compound between the relay's metal base and the heat sink for optimal heat transfer.
  • Ensure all terminal connections are secure to prevent arcing.
  • Use appropriately sized wiring to handle the intended load current.
  • Verify correct wiring for input (control) and output (load) terminals before applying power.
SSR-40AA AC to AC Solid State Relay - 2 Pack 1
SSR-40AA AC to AC Solid State Relay - 2 Pack 2
SSR-40AA AC to AC Solid State Relay - 2 Pack 3
SSR-40AA AC to AC Solid State Relay - 2 Pack 4
  • SSR-40AA AC to AC Solid State Relay - 2 Pack 1

    Perfect fit

    Diverse applications in controlling computer peripherals, AC motors, lighting systems, spanning automation setups to enhance security and performance
  • SSR-40AA AC to AC Solid State Relay - 2 Pack 2

    Premium quality

    This product adopts a heat-dissipating metal back plate and a copper terminal lug for superior conductivity.
  • SSR-40AA AC to AC Solid State Relay - 2 Pack 3

    Saving solution

    Enjoy the great feeling when your engine is repaired and works properly like before - BlueStars brings DIY solutions to help you deal with any trouble
  • SSR-40AA AC to AC Solid State Relay - 2 Pack 4

    Simple installation

    Solid State Relay is a simple part & just takes few minutes to install and will save you at least a hundred bucks in labor.
BRINGING RELIABILITY TO THE SWITCH

BRINGING RELIABILITY TO THE SWITCH

Compatible Models

Locate the model number of your appliance or equipment on the manufacturer's label and use it to check compatibility before ordering

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Model
‎SSR-40AA
Control method
‎AC to AC
Control (Input) Voltage
‎70-280VAC
Load (Output) Voltage
‎24-480VAC
Min Control Current
‎5MA
Max Control Current
‎20MA
Current & Frequency
‎40A
Insulation Resistance
‎1000M Ohm/500VDC
Off Leakage Current
‎≤5mA
On Voltage
‎≤1.6V
On-off-Time
‎≤10ms
Ambient Temperature
‎~30~+70℃
Relative Humidity
‎40-50% (Non-condensing)

FAQs

An SSR-40AA is an AC-input, AC-output solid state relay used to switch electrical loads electronically without mechanical contacts. It is commonly used in temperature controllers, heating equipment, industrial controls, and other applications where frequent on/off cycling is needed.
Common failure symptoms include the load not turning on, the load staying on when it should turn off, intermittent operation, overheating at the relay, or visible case damage. In control systems, you may also see a controller sending a signal but the connected heater, motor, or other AC load does not respond correctly.
Match the full part number SSR-40AA and confirm the electrical ratings and switching type required by your equipment. You should verify that your application uses an AC-input, AC-output relay and that the relay's current capacity is appropriate for the connected load. Also compare the terminal layout and mounting style with your original relay.
For someone familiar with electrical equipment, replacement is usually straightforward. Typical steps include disconnecting power, labeling wires, removing the old relay, transferring wiring to the new unit one terminal at a time, and remounting it securely. Basic tools often include screwdrivers and, in some installations, a nut driver or small wrench. Time required is commonly around 10 to 30 minutes depending on access.
Common causes include overheating, undersized heat sinking, loose terminal connections, current draw beyond the relay's rating, voltage spikes, and poor enclosure ventilation. In heating-control applications, repeated thermal stress can shorten service life if the relay runs hot for long periods.
Yes. Inspect the wiring terminals for heat damage or discoloration, verify that mounting surfaces are clean and secure, and check the connected load for shorts or excessive current draw. If the relay uses a heat sink, make sure it is still suitable and properly mounted. It is also wise to confirm that the control signal from the board or controller is within the required input range before powering the system back on.
Solid state relays generate heat during operation, so proper mounting and cooling are important. Always follow the equipment wiring diagram, tighten terminals securely, and avoid mixing up input and output sides. Because SSRs can fail either open or closed, testing the control signal and load behavior after installation is an important final step.