JLD404 sub panel monitoring

[Tech_Marco]

Bob:

You don't need to install an isolated transformer if the measured voltage is 500V or below. They put it there is just in case that you need to measrue over 500V and that transformer serves as a "ratio" transformer. For example, if the input could be as high as 1000V, you use a 2:1 transfromer and program the meter the ratio of "2". It will show you proper voltage


Marco

[bob21635]

Marco

Yes, I understand a stepdown transformer, but it's not needed here. Autotransformers are not isolated and can still pass full power to you. An isolation transformer is for safety only. You might want to add fig 7 & 8 to the manual download section? Have you tried crossing wires in a CT yet?

Bob

[Tech_Marco]

Marco

After an extensive search for small isolation transformers, this is the only source I found.
http://baida-china.cn/
They only cost $2 a piece, but have a minimum order of 200 pieces, since they are each custom made.
You could resell them on eBay for at least $10 and get more traffic flow to your website.
They can also be used with any other AC equipment on your website or elseware.
The power equipment I'm designing to sell would require them also.
I'll delete this post after you reply.

Bob

I won't belt on that price. $2 for that transformer, no way. It's one of tactics those seller on the Alibaba use to attrach traffic. They post a very low price for product they don't carry or they will ask you to buy something else. Just think about the size of the transformer and think about the cost. By the time you're ready to order, they will give you somethng else. For price of $2, you may end up a tiny tranformer like a quater size.

[Tech_Marco]

Marco

Yes, I understand a stepdown transformer, but it's not needed here. Autotransformers are not isolated and can still pass full power to you. An isolation transformer is for safety only. You might want to add fig 7 & 8 to the manual download section? Have you tried crossing wires in a CT yet?

Bob

Yes it's true that it add a 'layer' of safety to the meter so that we won't exposed to the high power AC220V. That little transformer could be a small one with low current. What we need is the "voltage" but not the current. Even a 1W isolated transformer will do the job well.

I haven't tried it as I don't have 1) load that run on AC220V 2) got no time as I'm preparing a trip to China on Monday. I'll shop around see if I can find a good deal


Marco

[bob21635]

While you are looking in China, make sure the isolation transformers can be used for 220V @ 50 hz and 240V @ 60 hz, so you only need one transformer,
also check on 120V @ 60 hz?