IEC inlet rated current

Hi ppl,

Is it safe to use an IEC connector rated at 1A with a 600mA (Secondary Current Nom.) transformer if the circuit draws around 500 mA? If so, is there any danger by doing so? Thanks 

According to international safety standard 60065:

The attachment plug shall have a current rating no lower than 125 % of the current drawn by the apparatus under normal operating conditions and a voltage rating appropriate for the rated voltage for the apparatus. When the apparatus is capable of being adapted for use on two or more different supply voltages by means of an input selector, the attachment plug provided with the apparatus shall be rated for the voltage for which the apparatus is intended to be connected when it is shipped from the factory.

Mains supply flexible cords shall... have an ampacity not less than the current drawn by the apparatus.

Hi merlin,

Thanks for the answer!

So (if I understood correct) in my case where the transformer is rated at 600mA and the circuit draws no more than 500mA, it is safe (and in accordance to international safety standard 60065) to use an IEC connector rated at 1A.

Please correct me if I'm wrong! 

warpie said:

So (if I understood correct) in my case where the transformer is rated at 600mA and the circuit draws no more than 500mA, it is safe (and in accordance to international safety standard 60065) to use an IEC connector rated at 1A.

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You seem to have quoted the secondary current as 500mA, yes? Presumably the primary current will be much less, yes? In which case a 1A connector would be more than enough.

Yes that makes sense

I have my doubts about the transformer, will it be able to manage inrush currents and peaks for charging the caps? If so, the average  rating it's ok, check the peaks rating and your circuit, if you don't have the rating of the transformers at least be sure your circuit inrush and peaks currents aren't insanely high compared to the average.

JS

joaquins said:

I have my doubts about the transformer, will it be able to manage inrush currents and peaks for charging the caps? If so, the average  rating it's ok, check the peaks rating and your circuit, if you don't have the rating of the transformers at least be sure your circuit inrush and peaks currents aren't insanely high compared to the average.

JS

Click to expand...

Yes, I was thinking the same last night so I decided to go with a transformer rated at 1A so that should be fine, right?
In that case the IEC connector will be 2A.

warpie said:

joaquins said:

I have my doubts about the transformer, will it be able to manage inrush currents and peaks for charging the caps? If so, the average  rating it's ok, check the peaks rating and your circuit, if you don't have the rating of the transformers at least be sure your circuit inrush and peaks currents aren't insanely high compared to the average.

JS

Click to expand...

Yes, I was thinking the same last night so I decided to go with a transformer rated at 1A so that should be fine, right?
In that case the IEC connector will be 2A.

Click to expand...

The IEC connector must be rated for the primary current, depending on your pri and sec voltage the current is probably much lower, power in pro and sec is almost the same (except for transformer losses which depends on the quality but less than 5% for sure. What voltages are you using, your mains and the sec of the transformer?

JS

joaquins said:

What voltages are you using, your mains and the sec of the transformer?

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+/-30VDC with a 50VA 2x25V transformer. Mains are 230V

warpie said:

Hi ppl,

Is it safe to use an IEC connector rated at 1A with a 600mA (Secondary Current Nom.) transformer if the circuit draws around 500 mA? If so, is there any danger by doing so? Thanks 

Click to expand...

What type of IEC connector is rated at 1 amp?

abbey road d enfer said:

What type of IEC connector is rated at 1 amp?

Click to expand...

That's one example..

http://www.schurter.com/var/schurter/storage/ilcatalogue/files/document/datasheet/en/pdf/typ_KFS.pdf

I think people are confused by the post title.
IEC cables/connectors are usually rated for 10Amps.
But in this case you're talking about the rating of an IEC socket with inbuild RF filtering.
That RF filter has a current limit. The limit is set by the wire thickness of the inductors inside.
You are using a 50VA transformer on 230vAC.
That is about 250mA.
The 1A socket will be fine. A 10A socket will be fine too, but bigger and maybe more expensive.
Leo..

Sorry for the confusion. ..

Maybe a moderator can change the title?

warpie said:

Sorry for the confusion. ..

Maybe a moderator can change the title?

Click to expand...

You can, edit your first post.

I'm not really sure how does it goes, but are you trying to take 60W (±30V 1A) from 50VA (25V 1A) transformer... That's not good, first with 25V you get 35V peak, then you have 1.5V, let's say 2V for the diodes, then there will be some ripple, even more than recommended since your transformer is rated just on the target current so you will be lacking capability to charge big caps. So, let's say 1V ripple, maybe even 2V, depending on the cap you could put to the transformer without burning it. Then you need a regulator, at least 3V at any time, so in the best case you'll have 29V output after the regulator, without taking care of a ±10% of the mains or other details. I would use a higher voltage for the transformer, and also higher current, maybe 1.5A 28V so something around 85VA I guess, so you can take a couple of spare watts to dissipate at the diodes and regulator, a couple of volts for better margin at the regulator plus bigger caps to reduce ripple. (Still 1A IEC is fine in this case, you could go for 230VA to have 1A, 25% less so up to 184VA is fine for that connector)

JS

Sorry my mistake, it's +/-28V but I don't think it makes much different.

It's actually the TG-1 project that I'm trying slowly slowly to complete. People use 50VA 2x25V transformer for this project (some people even used 30VA 2x25).

So, you suggest a 85VA 2x28V for a circuit that draws no more than 500mA? Interesting. I'll look into this.
Thanks for your help!

warpie said:

So, you suggest a 85VA 2x28V for a circuit that draws no more than 500mA? Interesting. I'll look into this.

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You need the transformer current rating to be at least 1.5 times the DC current. If the DC current is +30Vdc 500mA, -30Vdc 500mA, then a 50VA transformer will be fine.

warpie said:

Sorry my mistake, it's +/-28V but I don't think it makes much different.

It's actually the TG-1 project that I'm trying slowly slowly to complete. People use 50VA 2x25V transformer for this project (some people even used 30VA 2x25).

So, you suggest a 85VA 2x28V for a circuit that draws no more than 500mA? Interesting. I'll look into this.
Thanks for your help!

Click to expand...

Take what merlin said, my calcs were with different numbers, ±30V 1A and I would be short on margin then.

JS

Thank you gents!

I think I'll go for 50VA 2x25V as this will give me 35V after rectification, which should be sufficient..