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Any Ideas to prevent Failures of Solid State relays

K

karthik

Jan 1, 1970
0
I am using Solid state relays to On/Off heaters so as to control
temperature.
In case if heaters get short,immediately the Solid state relays ( SSR )
also gets short and
I need to change new one.Even though I have Fuse protection the SSR and
Fuse gets blown.
Since the Cost of SSR is high,I have so many troubles.

So any one Please suggest some ideas to prevent SSR failure.Is there
any protection like
Varistors , RC circuit to prevent this?????
 
P

Pooh Bear

Jan 1, 1970
0
karthik said:
I am using Solid state relays to On/Off heaters so as to control
temperature.
In case if heaters get short,immediately the Solid state relays ( SSR )
also gets short and
I need to change new one.Even though I have Fuse protection the SSR and
Fuse gets blown.
Since the Cost of SSR is high,I have so many troubles.

So any one Please suggest some ideas to prevent SSR failure.Is there
any protection like
Varistors , RC circuit to prevent this?????

Why have you posted this 5 times ?
 
J

John - kd5yi

Jan 1, 1970
0
karthik said:
I am using Solid state relays to On/Off heaters so as to control
temperature.
In case if heaters get short,immediately the Solid state relays ( SSR )
also gets short and
I need to change new one.Even though I have Fuse protection the SSR and
Fuse gets blown.
Since the Cost of SSR is high,I have so many troubles.

So any one Please suggest some ideas to prevent SSR failure.Is there
any protection like
Varistors , RC circuit to prevent this?????


Use a fuse whose I-squared-T rating is less than the SSR's semiconductor
device I-squared-T rating. Also use what is known as a sub-cycle fuse. If
you size the fuse this way and it's continuous rating turns out to be less
than the heater's normal current, your SSR is too small.

John
 
karthik said:
I am using Solid state relays to On/Off heaters so as to control
temperature.
In case if heaters get short,immediately the Solid state relays ( SSR )
also gets short and
I need to change new one.Even though I have Fuse protection the SSR and
Fuse gets blown.
Since the Cost of SSR is high,I have so many troubles.

So any one Please suggest some ideas to prevent SSR failure.Is there
any protection like
Varistors , RC circuit to prevent this?????

If your heaters keep shorting you need another make. You need the right
type of fuse ie thyristor semiconductor fuses these are also expensive.
 
karthik said:
I am using Solid state relays to On/Off heaters so as to control
temperature.
In case if heaters get short,immediately the Solid state relays ( SSR )
also gets short and
I need to change new one.Even though I have Fuse protection the SSR and
Fuse gets blown.
Since the Cost of SSR is high,I have so many troubles.

So any one Please suggest some ideas to prevent SSR failure.Is there
any protection like
Varistors , RC circuit to prevent this?????

How big a heater? 1500 watts? What kind of heatsink is the SSR mounted
on? Why are your heaters 'get(ting) short'? Others have pointed out
that THAT should be addressed -- like now. What is the rating of the
SSR? Is there a largish motor as part of the heater that could have a
large inrush?

In general, SSRs are fairly tough to blow up so what are you actually
doing to it?

GG
 
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