EEVblog Electronics Community Forum

Products => Test Equipment => Topic started by: 001 on January 24, 2018, 03:01:34 pm

Title: Intelegent panel meter from EBAY - NEED OPINIONS
Post by: 001 on January 24, 2018, 03:01:34 pm

I rehouse now my isolation transformer and variac in new enclosure
It is 0-440V up to 4A device

Now I`m looking for some sort of indication (V and A)
Is it will be ok? (is it possible to mod it for work below 220V (via separate PS)?)
It will be better replace current transformer to simple shunt but I can`t find this variant at EBAY  :-//

(https://s3-ap-southeast-1.amazonaws.com/a2.datacaciques.com/17/03/27/n7wzo16icyku27eg/eeffa78a6ba36b68.jpg)

And what about this?

(https://i.ebayimg.com/images/g/q3YAAOSwgZ1XrYWJ/s-l500.jpg)

Title: Re: Intelegent panel meter from EBAY - NEED OPINIONS
Post by: alm on January 27, 2018, 08:57:23 am

The advantage of a current transformer is that it isolates the meter from the live voltage, so no low-impedance connection needs to exist between the 440 V wires and the meter. I would say the meter in the second picture looks not at all suitable for 440 V. The exposed shunt, flimsy wiring and limited clearance would limit it to something like 50 V at best, in my opinion, even with an external voltage divider. Never mind that it is likely limited to measuring DC only, so you would need to add rectification and loose information about reactive power / power factor.