Solid State Relays or SSR
More about SSR
Here are many Types of SSR or Solid State Relays. In this
section you will find SSR designs and PCB layouts which you can
study. The PCB layouts have gone thru some revisions and they
worked quite well.
Read my FAQ -
SSR Open Circuit Leakage Voltage
- This will help you to
test them out.
Electromagnetic Relays -
The electromechanical relays have
moving parts. The terminology below came from them, these are
still used and very reliable. There is a spring action too and
the disadvantage of sparking in inductive loads. In SSR there is
no sparking, but have a ON Resistance that heats them up.
NO - Normally Open - when the relay is not energized or
activated, this terminal is open-circuit.
NC - Normally Closed - when the relay is not energized or
activated, this terminal is closed circuit.
COM - The Common Center Terminal in relays. This is the center
terminal that closes circuit with NC-NO.
The terminals are potential free and floating and are insulated
from the control signals or coil windings by many kilo volts.
Many provide visible isolation. These terms apply to SSR or Big
Solid State Relays -
They are called SSR as there are made of semiconductors and have
no moving parts to wear out. They do generate heat depending on
load and switching. Thyristors are used in most as they are
rugged, mosfets and IGBT may also be used for various
Another SSR Question I got years back -
Leakage of SSR driving AC Solenoid
In this section you will find SSR designs and PCB layouts which
you can study. These were made and sold by me years ago.
So the PCB layouts have gone thru some revisions and they worked
Many machines and equipment use some SSRs in their products
which may need replacement. So the SSR is not only sold to OEMs
but also to Service-Maintenance Market. These are also
modified as Output Modules for digital outputs coming from
embedded systems or Computers.
Precision Temperature Control with PID and SSR
SSR Enclosure Design
This is the enclosure for the Encapsulated Mini RTD PT100
Transmitter and also Solid State Relays - SSR.
Potted, Encapsulated in epoxy, hermetically sealed. It has a
Nickel Plated Aluminum Plate insert molded. For removing heat
The plastic is a fire retardant high temperature grade. The
epoxy is ciba araldite, fine alumina is filler. A transparent
terminal cover for safety. It costed me an equivalent of 600-700
USD for tooling plastic parts.
3 Phase SSR
This is a Solid State Contacter, it will switch R-Y-B
phases. It is a high power SSR. In some places it is unwise to
use an SSR, a Electromechanical Contacter will perform better
Three Phase AC SSR for 1 HP Motor
- How these pages helped
some people fix a Automation Solution.