Surge/over voltage protection

Siri

I am planning to connect a solid state relay(SSR) 12V input and 120 VAC load to my project(BS2px based) to switch a 110VAC motor.
·- ·AC motor rated at 110VAC· 60Htz- 0.55Amps.

The·application notes·from the SSR manufacturer·requires the addition of·"overload protection" as overload protection is not built-in to the SSR.
Is connecting a disk varistor in paralled with the AC·terminals of the SSR is·sufficient ? - ·if so please suggest values for the varistor or other easy way to solve this.

Thank you.

Siri

sam_sam_sam

Siri

Please give us a web page link to solid state relay(SSR) 12V input and 120 VAC
That you are going to use


The·application notes·from the SSR manufacturer·requires the addition of·"overload protection" as overload protection is not built-in to the SSR.
·
What this mean is that this device dose not have a fuse built in· so you will need to put a fuse>>>>>>>for what the rating of the solid state relay is


·Surge/over voltage
Is connecting a disk varistor in paralled with the AC·terminals of the SSR is·sufficient

I would put one on the power·going to the·SSR and one after the SSR
going to the motor·




I hope that help you in some way· ·



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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 9/6/2007 9:40:17 PM GMT

Siri

Sam,

I am attaching the manufactureres data sheet.

Thanks for your help.

Siri

sam_sam_sam

Siri

After reading the data sheet i would say that do what i put on the frist post

This is what i would do if i where doing this project ·the reason that i am·saying this is that i have a pool pump
that i am going to put on a 25 amp SSR the runnig amp are 10 amps but stalled is 21 amps now i do not want
this to last more than 3 seconds i will use a fast acting fuse rated at 20 amps so that if for some reason this pump is
jamped it will not have any power to it and burn out the SSR this cost $45.00 for this SSR and a fuse $2.00
I can replace alot of fuses before i get to $45.00· This SSR has a built in heat sink

What happen was one day when i came home from work··I heard the pump humming and not running
and the pump was very very warm not so hot that you could not touch it yet
but·i was able to fix what was wrong with this motor now is all well right now
·I am just using a relay

What I going to do is put a (current sensor This was not cheep $100.00)·on this pump and when the amps are more than 10 amp

I will also add a routine to the pool pump timer routine that will LOCK OUT the PUMP and will flash a LED that will tell me that something wrong with the pump

I would get the 8 amp verson and put a fuse that will handle the inrush current that if you plan on turn the motor
ON and Off alot in a short time frame·the fuse should blow in·5 seconds when the is stalled

You are rating the fuse for the motor not for the SSR

The reason for this that when you run a motor for lot of short burst the motor will run hotter


If this not the case then you maybe·able to·just use a fuse that would blow if the motor was
stalled and not running for let say 10 second the should blow when the motor is stalled

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··Thanks for any··that you may have and all of your time finding them

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·
·
Sam

Post Edited (sam_sam_sam) : 9/7/2007 2:09:38 AM GMT

Siri

Sam,

·Thank you very much for all the help will try what you suggested.

Siri