Hello,
I’m looking at these micro ring core CTs:
Especially this one, the DL-CT03CL2.0:
In the datasheet it says, that the Rated primary current is 5A, but the Measuring current range is 0-20A.
Do can I use this CT on 20A circuits, or just on 5A circuits?
Thanks.
I read it as saying that it meets the specification for accuracy at 5 A, but it is “usable” up to 20 A. But as this is all it says, and no numbers are attached to the saturation curve, it’s to a greater or lesser extent a meaningless number. I’m not sure what "Maximum current range " refers to - maybe the flat top of the saturation curve? One assumes these are all rms values, but it’s not explicitly stated.
The other point to watch is, although the sheets says Operating frequency: 50/60 Hz, it will saturate at a lower current (50/60ths lower) at 50 Hz compared to 60 Hz.
I think the only way to be sure would be to obtain a sample and measure it.
Just an observation. It may, or may not, be relevant here.
I noticed there was no price listed for any of the CTs.
I’ve found when a website doesn’t list the price for an item, it’s usually for one
of two reasons.
Either you don’t want to know. (i.e. it’s outrageous)
or
You have to order the item in quantity. e.g. minimum order is 50, 100, etc.
Then I think the DL-CT08CL10-2000/1 will be a safer bet for the 16A circuits:
I’m not looking at these because I want to find something cheap, but they are very small, and there is not much space in a DIN rail distribution box for clamps.
Initially, I found them on Aliexpress. I’m not sure if the link would be allowed or not, but the DL-CT08CL10-2000/1 I mentioned in my previous post is $0.94 plus $5.85 shipping.
If I buy 9, the price+shipping per piece is $2.34, so they are really good price wise.
(I’m currently designing a 2 module DIN rail power meter with 9 current channels.)
I look on the 2000:1 c.t. (how can you call a ring-core current transformer a CLAMP? -I do wish people would stop being utterly stupid and stop using that term.) with a lot of suspicion. For example, for most manufacturers, the rated current is the maximum current at which it performs within specification - it lists two currents higher than this. Do they mean it is for use with a meter with a base current of 20 A? And what is the unit “level” used to define the accuracy? do they mean 0.1 per unit? - in which case it’s rubbish.
As I wrote, the only way with a document like this is to measure one yourself. It would be worth gambling the price of one unit - I wouldn’t gamble the shipping cost.
I meant, that there is no space in the box for clamps, which are much larger (at least the ones that people usually use), that’s why I’m looking into these micro ring type CTs.
Yes, that’s totally understood and a ring-core c.t. will always be smaller and perform better than a split-core of the same rating. But the problem is, the data sheet doesn’t specify the device in terms that we in the western world understand - so you’re buying something that you don’t clearly know what it’s capable of.
