volts and amps with CT!

[pianotuna]

Hi,

These are a nice meter to monitor the 120 volt side of the RV:

https://www.ebay.com/itm/Digital-AC100-300V-0-100A-BLUE-LCD-DISPLAY-PANEL-VOLT-AMP-meter-With-CT/222...

[Gdetrailer]

myredracer wrote:

pianotuna wrote:
Hi,

These are a nice meter to monitor the 120 volt side of the RV:

https://www.ebay.com/itm/Digital-AC100-300V-0-100A-BLUE-LCD-DISPLAY-PANEL-VOLT-AMP-meter-With-CT/222...

Just wondering out loud... Is that CSA/UL listed? The voltmeter portion would not be an issue but a C/T in a circuit could potentially be (as noted above).

I permanently mounted an LED ammeter on the wall using a Datel mini panel meter with integral CT (full scale is 5 amps) and a remote 50/5 C/T similar to the 2nd photo to be able to read 30 amps. Datel meters aren't cheap but I found a deal on one on ebay...

FWIW, I rarely ever see much above 15 amps. A permanent LED voltmeter is def. one of the best upgrades you can ever do!

Doubt much if any of these low cost meters/CTs are CSA/UL tested and approved, just costs way too much to go through the certification processes (I work in a design/manufacturing environment, we do have to jump through a lot of hoops to get our products CSA/UL approved and the testing IS expensive and involved)..

Those costs are not absorbed by the manufacturer, they are handed down to the consumer in the form of higher prices.

The ones I have bought, have no CSA/UL markings.

Personally, unless you ARE building something to sell to "the masses" and you follow good electrical hygiene (enclose in proper electrical box, fuse the power leads, ect), those certs are not really needed..

[myredracer]

pianotuna wrote:
Hi,

These are a nice meter to monitor the 120 volt side of the RV:

https://www.ebay.com/itm/Digital-AC100-300V-0-100A-BLUE-LCD-DISPLAY-PANEL-VOLT-AMP-meter-With-CT/222...

Just wondering out loud... Is that CSA/UL listed? The voltmeter portion would not be an issue but a C/T in a circuit could potentially be (as noted above).

I permanently mounted an LED ammeter on the wall using a Datel mini panel meter with integral CT (full scale is 5 amps) and a remote 50/5 C/T similar to the 2nd photo to be able to read 30 amps. Datel meters aren't cheap but I found a deal on one on ebay...

FWIW, I rarely ever see much above 15 amps. A permanent LED voltmeter is def. one of the best upgrades you can ever do!

[Ed_Gee]

.

[ScottG]

time2roll wrote:

SidecarFlip wrote:

time2roll wrote:
http://www.progressiveindustries.net/ems-rds

That one is 92 bucks from Dell City. A witch is about 5 bucks....

Came with my PI EMS. No need for a second meter.

But the PI has that neat retro 70's LED readout! 😉
(I have one)

[Gdetrailer]

GordonThree wrote:
so it's sensing line voltage and current, using nothing but a current transformer? that's pretty cool. how does that work exactly? voltage is a potential, so what's the other reference?

No, has terminals for AC line AND the CT.

Uses the AC voltage to power the unit (IE "self power") then reads out the voltage plus reads the voltage across the CT.

I should note to folks who have never worked with CTs, they ARE transformers. The AC wire you put through the center of the core is effectively the Primary which is equivalent to one turn.

The fine gauge wire wrapped around the core creates the secondary and is the output.

Two types of CTs, one is swamped and one is not.

Swamped CTs have a RESISTOR in parallel with the secondary windings.

Non swamped DO NOT HAVE A RESISTOR BUILT IN.

The resistor is there to preload and pull down the voltage of the secondary to a safe voltage.

Non Swamped CTS CAN DEVELOP HIGH VOLTAGES across the secondary which can be lethal with no load attached!

Although these CTs most likely have a swamping resistor, one SHOULD TREAT THEM AS IF THEY DO NOT!

HANDLE WITH CARE!

Best practice is to always ensure the power source has been safely disconnected when working with CT secondary connections..

The back of these meters ARE fully open and you have live line voltage, it IS wise to mount these with some sort of electrical enclosure like you would with a AC outlet or light switch.

[time2roll]

SidecarFlip wrote:

time2roll wrote:
http://www.progressiveindustries.net/ems-rds

That one is 92 bucks from Dell City. A witch is about 5 bucks....

Came with my PI EMS. No need for a second meter.

[jkwilson]

GordonThree wrote:
so it's sensing line voltage and current, using nothing but a current transformer? that's pretty cool. how does that work exactly? voltage is a potential, so what's the other reference?

The schematic shows an AC power connection.

[GordonThree]

so it's sensing line voltage and current, using nothing but a current transformer? that's pretty cool. how does that work exactly? voltage is a potential, so what's the other reference?

[K_Charles]

2oldman wrote:
I love Chinese spelling:

Accrancy:1%±2 words
Speed:2 per/second

WTH do those things mean?

Under brand it says "does not apply"

[SidecarFlip]

time2roll wrote:
http://www.progressiveindustries.net/ems-rds

That one is 92 bucks from Dell City. A witch is about 5 bucks....

[time2roll]

http://www.progressiveindustries.net/ems-rds

[Gdetrailer]

HERE



HERE

And, yeah, I bought a few AC volt/amp meters a few years ago for my home gen setup, liked them so well I bought a another one for my RV..

Got the 30A ones for $9 back then, now I see only 100A versions for a bit more..

I added extra wire length to the CT to allow for remote mounting the meter.

My RV since it stays plugged in 24/7 at home I put a small toggle switch nearby to turn the meter off when not needed.. Svaes unwanted wear and tear on the backlight since the backlight stays on as long as the meter has power.

I also see there is Three Phase versions which I suspect might be adaptable for a 50A shore connection (ignore L3) which would eliminate the need to buy two meters for that setup.

[SidecarFlip]

For 12 bucks, even if it's inaccurate, it looks nice...lol

[2oldman]

I love Chinese spelling:

Accrancy:1%±2 words
Speed:2 per/second

WTH do those things mean?