Hi guys,

I've a small question regarding how to connect the terminals for 220V output. As per the diagram in below pic my understanding is :

Output terminal H1& H4
Output 220V: H1-H2=shorted & H3-H4= shorted
output 440V: H2&H3 shorted

Is this correct? I don't want to make any wrong connections and blow up things.Also the label says 0.120kVA & 0.150kVA for 220V and 440V respectively. What does that mean? How much max curent can be drawn from this transformer safely?

Thanks.

 

Hello,

The losses are different for the frequencies given:



Bertus

 

Correct for 220V, H1,2 shorted, and H3,4 shorted, ...

 

H1 and H4 for input and the jumpers as shown for the 220 side.
Max.

 

Hello,

The losses are different for the frequencies given:

View attachment 125490

Bertus

Hi,

My input is 120V @ 60Hz. So 0.150KVA means around 625mA right?

Correct for 220V, H1,2 shorted, and H3,4 shorted, ...

Hi,
So its H1-H2 & H3-H4 for 220V. The label actually made me confused wether its H1-H3 & H2-H4 for 220V or its like the pairing I mentioned in above post.

H1 and H4 for input and the jumpers as shown for the 220 side.
Max.

Isn't it X1& X2 for input?

 

Hello,

Looking at the label, H1 with H3 and H2 with H4, must be joined for use on 220 Volts.

Bertus

 

Isn't it X1& X2 for input?

That is the output side, the Industry convention is H for primary and X for secondary.
Max.

 

Hello,

Looking at the label, H1 with H3 and H2 with H4, must be joined for use on 220 Volts.

Bertus

Yes. Thank you for correcting me. I didn't notice that until you mentioned it now. It would have been a havoc if I used my config and plugged in.

That is the output side, the Industry convention is H for primary and X for secondary.
Max.

Thanks Max. I didn't know about it. There where two industrial transformer given to me by a friend. Got an extra one too, but it is twice the size of the one in this post. They where actually using the X side as primary (input 120V to step up to 480V).

One noob final question too. If I where to connect this transformer to a 120V 2.5A input how much would be the max current across 240V and 480V outputs? Is it somewhere between 500mA-650mA? And a short circuit or electrocution would be pretty bad right?

 

The label says that transformer is a 'machine tool control' transformer. It is not what you would call a power transformer, being rated at only 120 VA. Are you on the 50 Hz system?
That means 120 VA on the input side and also 120 VA on the output side ... So, calculate the volts times the amps and see if it exceeds the specification ... both sides ... leaving some to spare so that it doesn't overheat.

What does the other larger transformer look like? It may be a better choice for the numbers you are talking about.

 

The label says that transformer is a 'machine tool control' transformer. It is not what you would call a power transformer, being rated at only 120 VA. Are you on the 50 Hz system?
That means 120 VA on the input side and also 120 VA on the output side ... So, calculate the volts times the amps and see if it exceeds the specification ... both sides ... leaving some to spare so that it doesn't overheat.

What does the other larger transformer look like? It may be a better choice for the numbers you are talking about.

My outlet rating is 120V @ 60 Hz. So, what is the safe operating VA you recommend without over-heating? I'm not planning anything over 100VA with this. But this transformer is just for test purpose. The other big transformer I mentioned above is the one I'm planning to use more frequently. It also has same label like this, but its a 2kVA transformer. Here is the link to the transformer below.

http://www.newark.com/square-d-by-s...d31/industrial-control-transformer/dp/18C0082

 

OK ... Then the rated KVA for that transformer is 150. A safe load would be half that number, but run it as close to 150 as you want, as long as you observe the operating temperature ... overheating could cause problems.

 

OK ... Then the rated KVA for that transformer is 150. A safe load would be half that number, but run it as close to 150 as you want, as long as you observe the operating temperature ... overheating could cause problems.

A transformer overheating and when the insulation on the winding melts "KABOOM!!". Pretty scary.

 

At half power, you feel safe walking away.

 

Thanks Max. I didn't know about it. They where actually using the X side as primary (input 120V to step up to 480V).

They were obviously running it 'backwards' which can be done in a pinch to obtain 480v.
These transformers are generally used in a control enclosure where there is 3ph entry and these are used to obtain a standard 120v for control purposes.
Max.