Solid State AC Relay Module 5V x 1

5V logic compatible, controls 100-240VAC@2A

DESCRIPTION

The solid state relay module has one 5V logic compatible relay that can control up to 120/240VAC@2A

PACKAGE INCLUDES:

• Solid State Relay Module 5V x 1

KEY FEATURES OF SOLID STATE RELAY MODULE 5V X 1:

• 1 independently controlled SSR relay
• Phototriac coupler input isolation
• Switch 100-240VAC @ 2A
• LED indicator when relay is energized
• Built-in snubber circuit
• Zero cross control
• Active LOW control input
• 5V logic compatible, marginally 3.3V compatible.  See notes below
• 5V operation

Solid State Relay (SSR) modules are handy for controlling smaller AC loads.

This module switches one channel of AC at up to 2A.  The solid state relay can turn each AC channel ON or OFF, but it cannot be used for dimming.

Compared to a standard electro-mechanical relay, the solid state relay switches quicker and does not have the long-term mechanical reliability concerns of a standard relay as long as the maximum current limits are observed.  The main downside is that it cannot be used to control DC power and max current is limited to 2A.

Module Control

These modules are 5V logic compatible and marginally 3.3V logic compatible.  The reason it is marginally 3.3V compatible is that to turn the relay output off with a logic HIGH, the input must be driven to a minimum of about 3.1V if Vcc is 5V.  A 3.3V MCU output may or may not get high enough, though pull-ups on the MCU output will help.  If Vcc is less than 5V, then the logic HIGH voltage required to fully turn the relay off will also be less.

The input has a relay driver transistor which means the device needs < 1 mA on the logic control pin to drive it.  If you have a microcontroller like an Arduino, you can drive the relay using any of the digital output pins.  The relay can also be controlled with mechanical switches or appropriate sensors.

The relay is activated with a logic LOW signal.  There is a red LED that is lit when the control pin for the relay is driven low to activate the relay.  A logic HIGH deactivates the relay and the LED will go off.

Opto-Isolation

The relay has built-in phototriac coupler on its logic control input.

These phototriac couplers provide electrical isolation between the logic control input and the relay power as an added layer of protection in case of a major failure on the AC load of the relay.

Module Power

The module requires 4-6V power and ground to operate.  The ground must be common with the MCU for the control input to work.

The input has a reverse polarity protection diode in case the power connections are accidentally reversed.

When the relay is energized, the relay module draws about 10mA from the Vcc pin.

Relay Operation

The output of the relay is rated to switch AC power over a maximum range of 75VAC to 264VAC at 2A and suggested range of 100V to 240VAC.

Output is SPST type and is NO (Normally Open).  A logic LOW energizes the relay, so the two output terminals are shorted and power passes through the relay.  A logic HIGH (or no connection) de-energizes the relay and the output terminals are open.  As noted above, the logic high level needs to reach about 3.1V to fully shut the relay off when Vcc is 5V.

The relay operates at the zero cross point of the AC waveform so can switch every half cycle or 8.3mS.

The relay has a 2A soldered in fuse on the AC side for over-current protection.

SSR Active Low Schematic

Module Connections

1 x 3 Screw Terminal Block

• DC+ = 4-6VDC (5V typical)
• DC- = Ground from MCU or other control input.
• CH1 = Relay control input 1.  Logic HIGH level energizes relay 1

Relay Contacts (2 screw terminal block)

• Non-polarized = AC input side of hot lead (typically black wire) connects to one side.
• Non-polarized = Load side of hot lead connects to the other side.

OUR EVALUATION RESULTS:

These are nice relatively inexpensive modules that will work for a number of applications where lower power AC devices of up to about 220W @ 110V need to be controlled.  For a terrarium setup for instance, the module could automatically control the lights, heat lamp, heat rock, mister, circulating fan and similar devices.  Control of Christmas lighting is another popular type of application.

When switching AC power, proper safety should be observed to ensure the wiring is secure and not easily contacted to avoid an electrical shock.  These are often built into a electrical box with a terminal strip to make the AC electrical connections in a safe and secure manner.

Note that unlike mechanical relays, SSR relays cannot be operated in parallel to increase their current handling capability. This is because the relays will not turn on at exactly the same time and the first one to turn on will carry the full load until it fails or the fuse blows and then the second one will turn on and also subsequently fail.

For redundancy purposes, it is possible to operate 2 is parallel if the load is within the 2A limit of a single relay. If the relay carrying the load fails, the other relay will automatically switch on.

BEFORE THEY ARE SHIPPED, THESE MODULES ARE:

• Inspected
• Repackaged in high quality resealable ESD bag for safe storage.

FURTHER READING:

Omron SSR Technical Guide

Example application – Great Houdini Escape Room

Notes: 

1. None

TECHNICAL SPECIFICATIONS