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A static Switch Design

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thannara123

thannara123

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Switch Design by using Solid devices

Hello ,
I want to know to designing of a solid static Switch to replace my manual switch ,The switch rating is Volt 230 ,Ampere 6Amp. [Like a relay but not relay]

In detail ,
I need to change the condition of the switch by pressing a single button switch.

My thoughts is , it can be made by using a Thyristor or MOSFET or IGBT .



Any reference or tutorial is appreciable.
 
Last edited:

Thannara123, you don't say whether the switch is for AC or DC but assuming from the 230V it is mains AC you can't use an SCR (you CAN use two SCRs!) or the other devices you mention because they can only handle one polarity.

I think what you need is a Triac or two 'head to tail' parallel SCRs but tell us first how your switch is supposed to work and whether it has to be isolated for safety.

Brian.
 
betwixt said:
Thannara123, you don't say whether the switch is for AC or DC but assuming from the 230V it is mains AC you can't use an SCR (you CAN use two SCRs!) or the other devices you mention because they can only handle one polarity.

I think what you need is a Triac or two 'head to tail' parallel SCRs but tell us first how your switch is supposed to work and whether it has to be isolated for safety.

Brian.
Click to expand...
Yes the switch is need to work in AC 50-Hz and it need to be isolated for safety .
 

In that case the easiest solution is to use a triac opto-coupler for isolation and a small transformer to provide the DC supply for it's LED. If you use a standard logic driven design as shown on almost all triac data sheets, but just wire the switch to turn the LED current on and off it will satisfy all your requirements. You have the option of a normal or zero crossing opto-coupler, a normal one will switch the power on at almost any time, a zero crossing type will wait until mains AC passes through zero volts before turning on. For most purposes both will work exactly the same but a zero crossing one may cause less interference and stress on the device you are powering.

The DC feed to the LED should only need to pass ~10mA at a few volts and will be safety isolated so no special cables or switches are needed

Brian.
 
The usual solution would be a triac or dual scr solid state relays. I have e.g. used Sharp S202 and S216 series for similar applications like heater control.

Triac and scr as well as IGBT switches have 1 to 1.5 voltage drop and can't work without a heatsink at 6 A. Unlike a contactor, they are vulnerable to load short and overcurrent. That's why solid state relays are mainly used for applications with higher switching frequencies, e.g. > 0.1 Hz.

MOSFET pairs can act as AC solid state switch with lower voltage drop and respectively lower power dissipation, but the solution is relative expensive due to large required MOSFET area and neither ruggedized.
 
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FvM said:
The usual solution would be a triac or dual scr solid state relays. I have e.g. used Sharp S202 and S216 series for similar applications like heater control.

Triac and scr as well as IGBT switches have 1 to 1.5 voltage drop and can't work without a heatsink at 6 A. Unlike a contactor, they are vulnerable to load short and overcurrent. That's why solid state relays are mainly used for applications with higher switching frequencies, e.g. > 0.1 Hz.

MOSFET pairs can act as AC solid state switch with lower voltage drop and respectively lower power dissipation, but the solution is relative expensive due to large required MOSFET area and neither ruggedized.
Click to expand...

Sharp S202 and S216 series is not available in my area.
What about these type **broken link removed** ,Can i use it instead ,is this same type like sharp s202?

google given this circuit http://www.bowdenshobbycircuits.info/358heat.htm
 

Hi,

You don´t want to use a relay. You may have a good reason why.
Best is to tell us this reason, then we can recommend the best solution for you.

The reason can be: sound, speed, phase control, size, cost, power consumption, or anything else ... we don´t know...

Klaus
 
KlausST said:
Hi,

You don´t want to use a relay. You may have a good reason why.
Best is to tell us this reason, then we can recommend the best solution for you.

The reason can be: sound, speed, phase control, size, cost, power consumption, or anything else ... we don´t know...

Klaus
Click to expand...

The reason SIze and sound ,Also want to use the latest tech
 

Hi,

* Ready to buy SSRs: No sound, isolating...but usually they are bigger.
* Triac: not isolating
* Triac and MOC circuitry: No sound, isolating, I assume smaller than SSRs ... but you need to take care of safety isolation, creepage and clearance distance
* a smaller and a more silent relay?

Klaus
 
Might also consider photoMOS type solid state relays,
especially if the load is inductive (a problem for SCR
and TRIAC types, unless specially designed for the
out-of-phase I, V).
 
dick_freebird said:
Might also consider photoMOS type solid state relays,
especially if the load is inductive (a problem for SCR
and TRIAC types, unless specially designed for the
out-of-phase I, V).
Click to expand...

photoMOS type have high cost and low ampere rate :thinker:
 

Do it like this:
20171028_232808a.jpg

The transformer can be very small as it only has to supply a few mA. For the resistor marked '*' use the formula:
((Transformer RMS * 1.4) - 2) / 0.01 where the transformer RMS is the secondary voltage of the transformer.
For example with a 6V RMS transformer use ((6 * 1.4) - 2)/ 0.01 = 640 Ohms.

Note that the switch and any wiring to it is isolated from the AC line.

Brian.
 
betwixt said:
Do it like this:
View attachment 142107

The transformer can be very small as it only has to supply a few mA. For the resistor marked '*' use the formula:
((Transformer RMS * 1.4) - 2) / 0.01 where the transformer RMS is the secondary voltage of the transformer.
For example with a 6V RMS transformer use ((6 * 1.4) - 2)/ 0.01 = 640 Ohms.

Note that the switch and any wiring to it is isolated from the AC line.

Brian.
Click to expand...

which triac is ther e any number ?
 

Use any triac with suitable voltage and current ratings. All but the very biggest industrial devices can be triggered by a MOC opto-coupler.

If your load is reactive, consider using a 'snubberless' type or adding an RC snubber across the triac. The MOC data sheet explains how to do it.

Brian.
 
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