ETD49 Overheating

[badboy_6120]

If you don't have thermal shutdown/trafo overheat protection then I'd measure at highest possible mains voltage (265 VAC for 230+-15%)

Can you introduce a good and reliable way for applying transformer overheat protection?

 

[Jagd.Panther]

Can you introduce a good and reliable way for applying transformer overheat protection?

A bimetal switch like that:
https://www.google.com/search?num=3....5.0....0...1c.1.64.serp..3.4.692.PGqLOaeWFe4

taped or glued to the hottest part of the transfromer. If you are cooling the transformer with a fan the thermoswitch should be from the opposite side, so it's not cooled by the fan.

 

[badboy_6120]

A bimetal switch like that:
https://www.google.com/search?num=3....5.0....0...1c.1.64.serp..3.4.692.PGqLOaeWFe4

taped or glued to the hottest part of the transfromer. If you are cooling the transformer with a fan the thermoswitch should be from the opposite side, so it's not cooled by the fan.

Thank you
I was wondering if this was the method

 

[lynxlynx]

I once got big dead UPS with IGBT half bridge and collected such a switch from it. It was on big large heatsink IGBTs were on which I also grabbed from it.

 

[Jagd.Panther]

Hi everyone

I wound the primary test winding with 10-12-14-16-18-20 turns one after another and measured the cores temperature in idle condition as below:

10 turns: after 1 hour=87°c
12 turns: after 1 hour=79°c
14 turns: after 1 hour=70°c
16 turns: after 1 hour=60°c
18 turns: after 1 hour=53°c
20 turns: after 1 hour=46°c

room temperature was in the range of 27°c to 30°c

How was the core cooled? Convection cooled or forced cooled with a fan?

and another thing, one side of cores was less hotter than the other side (about 10°c)

Do you mean one half (E-shaped) was hotter than other one?

**above temperatures are measured from the most hottest point of transformer cores**
**frequency in above measurements was set to 70khz**
should I go with 18 turns or 20???

I'd go with 18 (or even 16) for forced cooled transformer and with 20 turns otherwise.

 

[badboy_6120]

How was the core cooled? Convection cooled or forced cooled with a fan?

I didn't use any cooling method in my measurements

Do you mean one half (E-shaped) was hotter than other one?

No, I meant the sides that consist of two legs of cores

I'd go with 18 (or even 16) for forced cooled transformer and with 20 turns otherwise.

Do you have any picture that shows how to apply force cooling to transformer??

By the way
What is the proper temperature of thermoswitch to shutdown the smps?(overheating protection)is 90"c ok?
I was thinking to use two thermoswitch, one for activate the fan on transformer (in about 60"c) and one as mentioned above to shutdown the smps in case of overheating
How about it?

 

[MicrosiM]

@badboy

Try running your SMPS at 125Khz, and measure the heat of the ETD49 core in idle.

Let me know results

 

[badboy_6120]

@badboy

Try running your SMPS at 125Khz, and measure the heat of the ETD49 core in idle.

Let me know results

With 22 primary turns??

 

[badboy_6120]

Try running your SMPS at 125Khz, and measure the heat of the ETD49 core in idle.

Let me know results

59°c in more than one hour in room temp of 28°c

**Primary turn= 22

 

[wally7856]

I don't suppose you are ready to try what i told you to do 3 days ago. 25 to 30khz.

 

[MicrosiM]

59°c in more than one hour in room temp of 28°c

**Primary turn= 22

Are you using original CORES?

 

[badboy_6120]

I don't suppose you are ready to try what i told you to do 3 days ago. 25 to 30khz.

Sorry
I'll run the smps as you told and share the results

 

[badboy_6120]

Are you using original CORES?

I will share the details about my ETD49 cores as soon as possible for you

 

[badboy_6120]

Here is the information about my ETD49

 

[badboy_6120]

I don't suppose you are ready to try what i told you to do 3 days ago. 25 to 30khz.

Because I changed the primary turn to 18 I just set the frequency to 40 to get around flux density you aimed for (~1650 gauss)

Temperature after 1 hour about 65°c

I get 85°c after 30 minutes with 10 turns in primary at 70khz frequency (about 1650 gauss)
So the problem here is that my cores can't run at high frequencies

 

[wally7856]

In post 17 you said you had MF102 ferrite material, now in post 54 you say you have 6H20 material. Do you have two different cores?

What is your measured AC input voltage?

 

[badboy_6120]

In post 17 you said you had MF102 ferrite material, now in post 54 you say you have 6H20 material. Do you have two different cores?

What is your measured AC input voltage?

MF102 is for ETD59
6H20 is for ETD49

I'm using ETD59 in my smps but I post information about ETD49 because "Microsim" asked about it



My input AC voltage is around 240V (sometimes it goes up to 250V)

 

[wally7856]

badboy i am trying to work out what you have. Do you have an official winding width for your bobbin. I want to know how many primary turns can fit on one layer. You may know this from your experimenting.

 

[badboy_6120]

badboy i am trying to work out what you have. Do you have an official winding width for your bobbin. I want to know how many primary turns can fit on one layer. You may know this from your experimenting.

it's very kind of you
I appreciate it

If I use 36x0.25mm wire for the primary I can fit 17 turns on each layer of ETD59 bobbin and 13 turns on ETD49

 

[wally7856]

OH boy, i thought 18 turns would fit, now i have to recalculate everything. With 17 turns do you have any margins between wire and bobbin for safety.