AC Solid State Relay - 280V 20A Zero-Cross Turn-on, 3953_1

£22.03 £18.36

This SSR switches up to 280VAC / 20A and connects to a PhidgetInterfaceKit 0/16/16 or OUT1100.


For AC switching applications, this solid state relay is economical and reliable. Using the digital outputs from a Phidgets device such as the OUT1100 - 4x Digital Output Phidget, you can control the relay to silently switch an AC circuit at 280V/20A or less. This relay has a Zero-crossing turn-on, which means it waits for the AC signal to cross zero before switching on. For an explanation of what this means, please visit this sectionof our SSR primer.

If your SSR is overheating, you should consider getting a heat sink for safety. This SSR comes with a heat transfer pad that can be placed between the metal base of the SSR and the surface it's mounted to in order to help encourage heat flow. It also comes with a varistor that can be used to protect your SSR against voltage spikes in some applications.

Comes Packaged with


This SSR comes with a heat transfer pad and a protective cover. Use the heat transfer pad whenever mounting the SSR on a heat sink or metal surface. We recommend that you use the plastic cover if there is any risk of a person or conductive material accidentally touching the load side contacts. The other AC we relays we've sold in the past have come with an external varistor. This relay has additional protective circuitry inside, so an external varistor is not needed.


This relay can be controlled using a Phidgets relay output board. See the Connection & Compatibility tab for details.


  1. If you're running the SSR close to it's maximum current rating, you'll probably need to mount it to a heat sink or a surface that can function as a heat sink.
  2. Use the heat transfer pad between the SSR and the heat sink. Failure to do so can cause overheating and could damage the relay.
  3. Make sure that the SSR terminal screws are tight. If the screws are not tight, the SSR will get damaged by heat generated when the power is ON.
  4. When an SSR fails, it most often fails permanently closed - leaving your load powered, and possibly creating a fire or safety hazard. Be sure to have failsafes in these situations.
  5. Make sure that you use the relay within the product specifications.
  6. Ensure that the relay terminals are covered or protected when switching high voltage loads.

Electrical Properties

Isolation Method


Dielectric Strength

4 kV AC

Control Voltage Min

4 V DC

Control Voltage Max

32 V DC

Load Voltage Max (AC)

280 V AC

Load Current Max (AC)

20 A

Load Surge Current

200 A

Relay Turn-on Type


Turn-on Time Max

(1/2 cycle plus) 1 ms

Physical Properties


58.6 mm


45.7 mm


26.5 mm

Operating Temperature Min

-30 °C

Operating Temperature Max

80 °C

Other Properties

Manufacturer Part Number


* - For an explanation of what this means, please visit this section of our SSR primer.