How SSR can be driven by digital and analog?

unsaint32 · Dec 10, 2013

I was studying Omron E5CN temp controller. I read in its manual that in order to drive a SSR, I have to use a temp controller with voltage output. (The control output can be relay, voltate, current types)
I always thought a SSR is used because of high on/off resolution. Then it requires digital output contacts (like PWM output) to drive the SSR. How does an analog output such as the voltage output drive an SSR?
Thanks.

iant · Dec 10, 2013

SSR - solid state relay
some of these switch an output on with an input voltage
eg. 24Vdc - when you vary the input you can vary the output
- Analogue control

unsaint32 · Dec 10, 2013

iant said:
SSR - solid state relay
some of these switch an output on with an input voltage
eg. 24Vdc - when you vary the input you can vary the output
- Analogue control

I don't understand. So, when I control a 240V heater with a SSR, 24V input to the SSR produces higher voltage to the heater than 10V input to the SSR?

Highland Controls · Dec 10, 2013

The voltage output on your controller is also known as a digital output. The voltage doesn't vary. It is either on or off, but it can be turned on and off very quickly. The solid state relay uses this logic signal to turn on its output(which equals the input), which in your case is 240VAC.

sinbernal · Dec 11, 2013

How SSR can be driven by analog?

Hello There, I am new with control system. I have a similar question. My application require to control an electric heater bank with a temperature controller. All the heater banks shall be modulated via new solid state relays in response to a 0 - 10 VDC analog control signal from the PLC. How can this be achived /posible. Kind Regards,

Highland Controls · Dec 11, 2013

You are probably talking about SCR's instead of SSR. SCR's can take an analog signal and use that to modulate the output.

bigbuckaroo · Dec 11, 2013

There are also companies that supply a circuit board device that you attach to a SSR in order for it t accept analog inuts to vary the output, similar to an SCR. HB Controls is a company that I have used these devices from and they work rather well. It comes with different options that can cover a wide range of applications.

iant · Dec 11, 2013

Highland Controls said:
You are probably talking about SCR's instead of SSR. SCR's can take an analog signal and use that to modulate the output.

That's the one I was talking about.
But.
It is a Solid State Relay. An SCR is a silicon Controlled Rectifier. Which is switched electronically.

To the OP
No you can not produce 240 from 24 Vdc
You need a 240 V supply as well

iant · Dec 11, 2013

Another current poster
http://www.plctalk.net/qanda/showthread.php?t=84113
This will help

How SSR can be driven by digital and analog?

unsaint32

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