PEA meters--always right?

[SunshineHarvey7]

I have a curious question... I was wondering about a voltage drop my friend has, so I decided to use a couple of these meters to monitor his power--one connected at his light meter, and the other one at his 100A cutoff switch at his property (1000 M away). Anyhow, here's the meter I'm using:

 

 

I put one at both ends of the line because I can see at a glance what the voltage is at either end as well as the load in watts or amps. These meters also have accumulated Kilowatt hours, so naturally I was eager to see how many kilowatt hours we are actually getting at the property versus what we are using straight out of the light meter.

 

Just out of curiousity, I noted the PEA meter reading as well when I began monitoring. After running with these meters attached for 5 days, I subtracted the difference with all three meters, and here's what I found:

 

PEA meter: 200 kwh of usage

My meter attached to the PEA meter: 150 kwh of usage

The meter at my property: 120 kwh of usage

 

Now 150-120=30kwh, and I was not surprised that we lost 30kwh on the line from the meter to the property since the wire is too small. What I can't explain is, why is the PEA meter reading so much higher than my meter that is hooked up directly to it?

 

I thought perhaps the induction current detector (the clamp-on device to the right of the meter in the photo above) might be flaky, so I checked the amp reading on that meter against my clamp-on meter, and they basically agreed (within 5% at least).

 

We actually had someone out here from PEA this morning, and I asked them about the difference. Unfortunately, I don't understand what all they said in Thai, but my translator said it was something about a voltage drop from the light meter to my meter, or something about power being consumed inside the PEA meter. Either way, sounds kinda fishy to me since my meter is hooked directly up to the output of theirs. Could my "cheap" (400THB on Shopee) meter be that far off?

 

What do you think?

[Crossy]

That does seem to be a big difference even for a cheapo energy meter.

 

Do your meters take account of power-factor? That could be a significant factor.

 

Did you check your meter's voltage readings agree with your check meter?

 

Try swapping your two meters, just to see if the difference in readings remains the same way round.

 

To be honest I would trust the PEA meter unless it's overloaded (they never read low then). PEA will happily swap your meter for a new one and a fee of course. Over what time period did the 200 kWh of usage accumulate?

 

We have decent energy meters installed which I use to monitor our solar, they don't agree exactly with the PEA box (our meters read high compared with PEA).

[GregTN]

I have a similar meter wired into my CU and with our average 400-500kwh use per month it measures about 15 units higher/month than the 4 year old 15/45 PEA meter, so pretty   close.  I don’t know if all these measuring devises  operate the same way but the induction coil on mine is directional and marked with an arrow to show the proper orientation to the wire.

[SunshineHarvey7]

3 hours ago, Crossy said:

That does seem to be a big difference even for a cheapo energy meter.

 

Do your meters take account of power-factor? That could be a significant factor.

 

Did you check your meter's voltage readings agree with your check meter?

 

Try swapping your two meters, just to see if the difference in readings remains the same way round.

 

To be honest I would trust the PEA meter unless it's overloaded (they never read low then). PEA will happily swap your meter for a new one and a fee of course. Over what time period did the 200 kWh of usage accumulate?

 

We have decent energy meters installed which I use to monitor our solar, they don't agree exactly with the PEA box (our meters read high compared with PEA).

 

I can click a button to see the average (or current?) power factor. Every time I've checked so far, the power factor has been 0.95 or better. (Most of the power is drawn by fans and a high-wattage rice cooker, I believe, for whatever that's worth.)

 

The voltage readings do agree with my check meter.

 

I just might swap meters and see what happens. Unfortunately, I'm scheduled to leave in less than 24 hrs., so we'll see what I can learn. ...

 

I do lean toward believing the PEA meter is probably correct. It's far from being overloaded. (It's a 15(45) meter, and it's quite unusual for us to exceed 15 amps.)

 

We accumulated the 200 kWh of usage in 5 days, which is in line with our last electrical bill--1200 kWh in 30 days. (Both averaging 40 kWh per day.)

[SunshineHarvey7]

1 hour ago, GregTN said:

I have a similar meter wired into my CU and with our average 400-500kwh use per month it measures about 15 units higher/month than the 4 year old 15/45 PEA meter, so pretty   close.  I don’t know if all these measuring devises  operate the same way but the induction coil on mine is directional and marked with an arrow to show the proper orientation to the wire.

If mine were that close, I wouldn't worry about it. I haven't seen a directional arrow on this coil. I would have assumed that the direction of the coil is important only with a DC circuit. Should it make a difference with AC? And if it did make a difference, wouldn't it be reading negative amps instead of positive?

[GregTN]

I actually would have thought the direction would not matter but the instructions caution you to take note of the placement of the mutual inductor (coil) and there is an actual arrow on it.  Anyway I know a lot of these instructions are not very clear sometimes and thought it might be something to check.

[Crossy]

1 hour ago, SunshineHarvey7 said:

And if it did make a difference, wouldn't it be reading negative amps instead of positive?

 

It might read negative Watts.

 

A lot depends upon how clever the internal software is (or isn't), it's not actually that easy to do the sums arithmetically, two coils and a spinning aluminium disc do the job so much better (conventional meter).

 

[SunshineHarvey7]

41 minutes ago, GregTN said:

I actually would have thought the direction would not matter but the instructions caution you to take note of the placement of the mutual inductor (coil) and there is an actual arrow on it.  Anyway I know a lot of these instructions are not very clear sometimes and thought it might be something to check.

Interesting, indeed. My directions are a bit different:

 

 

So, you can see why with my meter I can't see that it should make a difference. In fact, the coil has no arrow on it. Although it does have red and black leads, there is no suggestion that it matters how the red and black wires are matched up with the two designated screw terminals. Here's a shot of one of my hookups:

 

 

I do appreciate your helpful suggestion.

[millymoopoo]

19 hours ago, Crossy said:

That does seem to be a big difference

Usually these older analogue-rotating disc (mechanical) meters are quite accurate.
The only notable problem can be incorrect wiring, which will cause them to run in reverse, obviously PEA would be very quick to correct that problem if it does happen.

If anything, as they age they can become slightly slower.
The clip on (current transformer) induction type equipment you use could well be less accurate.

And certainly the long distance between meter and consumer is a problem.
The clip on meter needs to be attached over the load (active) wire only, not the load and return wires (active and neutral), also as close as possible to the PEA meter.
If there is still a difference and you have a friendly neighbour who is close to their meter, connect your clip on device to the load wire of their supply and after a time compare the two for difference, if there is little or none, it could suggest your equipment is OK and your PEA meter is suspect.!

[rodger]

I had a similar issue and found the problem to be the Current Transformer was around the Neutral not Line. My initial reaction was this should not be an issue but measuring the current on both Line and Neutral with a clip-on ammeter showed the difference. Investigating showed the difference current was flowing through the earth.

I worked with meters a lot in a past life and generally they are pretty accurate and contrary to popular myth actually slow down when aged, so if you have a clunky meter keep quiet.

The reason for the current split between the Neutral and Earth is a different topic and I will not go into it in this post.

Any power loss between the PEA meter and your check meter should be negligible. Unless you have crappie conductors the resistance should be very small and not introduce much loss.

Moral of my reply is ensure your electronic meter current coil is around the Line conductor.

[DTL2014]

i have a stabiliser for my a/v equipment which displays the power ...mostly 235v...

 

if the power was regulated to 220v somehow....would the bills be lower?

 

is there a way to do this.

 

[Sydebolle]

It is in the wiring. Apart from the PEA-wiring you might want to check if a friendly neighbour is running his fridge, TV and A/C on your bill ........ 

[bankruatsteve]

1 hour ago, DTL2014 said:

 

if the power was regulated to 220v somehow....would the bills be lower?

No.  The VA will be the same. 

[sometimewoodworker]

1 hour ago, DTL2014 said:

i have a stabiliser for my a/v equipment which displays the power ...mostly 235v...

 

if the power was regulated to 220v somehow....would the bills be lower?

 

is there a way to do this.

 

No they won’t be lower as it’s KWh 

[BoganInParasite]

We are having a little issue with our PEA meter at the moment. Noticed early in May it was at 11,999, took a photo to commemorate it nearly ticking over to 12,000. Got the account notice on the 21st and thought it was a bit low. Wife pointed out end reading was still 11,999. Went to the meter and confirmed it had not moved for a couple of weeks. The wife made a call and got a PEA number to report the meter which she did. Still not fixed and still stuck at 11,999. Call me paranoid but I decided to get more photos displaying date/time stamp and showing glass and seals intact so there would be no accusation of tampering. We are going to go to the local PEA office later in the week and once again report it is not reading. In the meantime it has been hot and we decided to take advantage of the meter not working. Fully expect there will need to be some adjusted payment once it is all sorted but it is likely to be at a lower rate than our current consumption which is higher since we are running the air-con 12 hours a day.

[CH1961]

On 6/1/2021 at 12:15 PM, SunshineHarvey7 said:

After running with these meters attached for 5 days, I subtracted the difference with all three meters, and here's what I found:

 

PEA meter: 200 kwh of usage

My meter attached to the PEA meter: 150 kwh of usage

The meter at my property: 120 kwh of usage

200, even 120 units in 5 days? 

There is something wrong in this story. 

[Crossy]

3 hours ago, CH1961 said:

200, even 120 units in 5 days? 

There is something wrong in this story. 

 

We use 40-60 units per day.

 

[CH1961]

15 hours ago, Crossy said:

 

We use 40-60 units per day.

 

Indoor farming? 

Bitcoin mining? 

 

Or just old single speed AC and longing for the british cold weather? 

[Crossy]

35 minutes ago, CH1961 said:

Indoor farming? 

Bitcoin mining? 

Or just old single speed AC and longing for the british cold weather? 

 

We are nearer 40 when the A/C adoring grandkids aren't here, and yes, the A/Cs in their rooms are conventional.

 

Other than that, none of the above ???? 

 

It's also worth noting that of the 737 units we've used so far this billing cycle 452 have been "free" from our solar. We're heading for a potential bill of around 500 units this month, less than April so no PEA discount ????