Calculate maximum power that can be controlled by 8A triac

[the_merovingian]

I'm designing a circuit that uses a opto-triac (MOC-2030) and triac (BTA08-600C) to control (dim) a lamp.

The BTA08-600C triac is rated as below:

http://www.datasheetcatalog.com/datasheets_pdf/B/T/A/0/BTA08-600C.shtml

It(RMS) 8 Amps
VDRM/VRRM 600 V

Can someone please tell me the largest lamp (in Watts) I can safely control without burning out the triac?

Thanks in advance.

 

[karesz]

If you has 230V main voltage: 8A x 230V- ca. 1.8KW>> IF TRIAC COOLING RIGHT DESIGNED IS!
K.
OH-OH!
These is not a 8A typ!! - only in TO220!
If you have i.e. D2Pack, it has by ca. +70Cels ambient so ~max 1.5A!!
Also you can with D2Pack and designed cooling not more as ca. 1.5x230=300W control...

 

[the_merovingian]

Re: Calculate maximum power that can be controlled by 8A tri

Thanks, that's what I thought (P=IV).

I have it in the TO-220AB Insulated package - so should be good for a 25W lamp

 

[karesz]

Hi,
Your part has a Rth of 60Cels/Watt!!
Also with a 20W lamp you have with ca. +8 Cels to your aktuel ambient temperature to add=surly do not need heath sink under +100 Celsius ambient!
K.
Other ? if your lamp has a short(life cycle end)...

 

[penrico]

Re: Calculate maximum power that can be controlled by 8A tri

If you has 230V main voltage: 8A x 230V- ca. 1.8KW>> IF TRIAC COOLING RIGHT DESIGNED IS!
K.
OH-OH!
These is not a 8A typ!! - only in TO220!
If you have i.e. D2Pack, it has by ca. +70Cels ambient so ~max 1.5A!!
Also you can with D2Pack and designed cooling not more as ca. 1.5x230=300W control...

Hey, it can handle 1800W without problem!. The TRIAC will not heat cause, the TRIAC never disipates it self all the power.

When the triac is in off state the current is 0, so when the triac is in the off state, the power on triac is 220V x 0A = 0W.
When the triac is in the on state, the current could be up to 8A, but the voltage across the triac is arroun 1,5V. So the power on triac will be 8A x1,5V = 12W.

With a good heatsink you can keep the triac on a safe temperature. The TO-220 case has a thermal resistence of 1,8°C/W. 12W means 21,6° over ambient temperature.

 

[karesz]

Hi Fun!
Sorry, but all devices do dissipate_thats life:-(!
Triacs has rest voltages at 1.5V multiply it pls with your current=you have the heath to dissipate!
These Triac has thermal resistance of 60C/W!!
Check pls pp2, top part of datasheet....Remember pls; not all producer has the same Rth for the same packages, but your 1.6C/W is far away the reality theses packages...
I think you can agree with me-or?
Greatings!
K.

 

[penrico]

Re: Calculate maximum power that can be controlled by 8A tri

karez,

Yes, that triac has 60°C/W Rth junction-ambient. But, it has 2,5°C/W juntion-case. So, it says that if you use a heatsink the total Rth is the Junction-case thermal resistance plus the heatsink resistance.

You can see what is the resistence of some heatsinks here:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=294-1082-ND

It says that these heatsink have a 4°C/W Rht.

So, Rht from junction to ambient will be 2,5 + 4 = 6,5°C

If the triac disipates 8 x 1,5 = 12W, the junction will be at 12x6,5 = 78°, if the ambient temperature is 40°, the junction will be at 118°. That is lower than 125°. So the triac could work.

Sure, it's not a good choice to use it up to 1800W, but it teoricaly works.

 

[karesz]

HAllo penrico,
If you will read my first comment pls; Im writing the same, its possible, but only "if Triac cooling right designed is"... Than, if a bulb will be wrong_at life end_ it becoms usually a massive short!_ thes is very important for saving reserve for your components dissipation.
To end dont forget pls, that if the heath shink has silikon film, it has + ca. 0.5 Cels/W in the Rths chain... I will say personally, use it not over 1.5 KW , or maybe better not more as 1KW, if you are in some mediterraine region...
K.

 

[penrico]

Re: Calculate maximum power that can be controlled by 8A tri

Karez,

OK, ok, I just want to clarify the things. We both says the same, but in differents ways.

Have a nice day

 

[karesz]

Your welcome!
Wish the same!
K.