Lies, Damn Lies and Cheap Power Meters

PA050027I have had and used an Electus power meter for about 12mths since they became available in Australia. I figured it was just like the American Kill-a-watt. Diligently collecting and comparing devices to see what they used and how much I was wasting with standby power. Dan did an early review on DansData.

ATA reported some accuracy concerns early on, and stopped selling them. The indication was this was only minor, and at low power settings.

I recently purchased the newer Solarinverters (SI) replacement from ATA and found some VERY large discrepancies between what I had seen before. Unsure as to which one to trust, I fired up the clamp meter to validate the results. The results shocked me.

I then confirmed the results against two other Electus meters of the same model.

The Electus meters are TOTAL AND UTTER JUNK. The numbers that come out have NOTHING to do with reality. The behaviour does not even appear to be linearly consistent.

Device Electus SI PF (SI) Fluke

Ent System

143w

317w

0.80

1.6

Washing Machine

17w

3w

0.16

n/a

PC & Acc

85w

199w

0.71

1.1A

Kettle

2550w

2340w

1.00

9.8A

11W CF Bulb

9W

14W

0.68

n/a

Water Pump 449w 472w 0.95 2.0A

Disappointingly Jaycar is still selling them.

The below pictured numbers are all with the SAME LOAD – a computer, UPS, Router, Printer etc. All numbers were repeated three times and fluctuations were minimal at this time.

PA050021
Fluke meter validation Rig

PA050023
1.1 Amps on Clamp Meter

PA050024
0.37A on Electus Meter – kinda disagrees with the 1.1 on the clamp meter. This is where the majority of the error seems to lie.

PA050026
1.16A on SI Meter

PA050027
The voltages read the same

PA050025
85W – 0.92 PF from Electus – again, the electus can’t seem to cope with PF giving readings that are often clearly incorrect. This will significantly affect the wattage calculation.

PA050028
0.71 PF from SI – this is about what I would expect.

PA050030
199W from SI

PA050029 
278VA from SI – matches the Fluke

PA050032
Units from rear

PA050033
Units from front

Now my clamp meter hasn’t been calibrated, but it is a Fluke. It’s only got one decimal place of precision. Using my other Fluke as an inline ammeter with mains voltages was too risky (exposed terminals) for me, so I didn’t do it, depsite the extra decimal place of precision.
I don’t have an independent Power Factor meter. I could be telling lies, this is the internet. The above numbers aren’t a small % error. They are out by over 100%. This is not a minor calibration issue, this is a device that clearly misleads Australian consumers.

I’ll stick with the new one and redo the testing round my house.

6 Responses to “Lies, Damn Lies and Cheap Power Meters”

  1. Munter says:

    Very dissapointing indeed. Do you think Jaycar could be pressed to recall the meters?

  2. LT says:

    The ATA made Electus (Jaycar’s wholesale division) fully aware of the problem, we returned close to 20 of these meters. Their response was ‘oh, it was just the first batch’. This was complete garbage of course, my general feeling having dealt with them over the years is they simply don’t give a stuff, so long as they make sales…

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  5. Evan says:

    Those Power Factor numbers for the SI are weird. .16 is impossibly low. I wonder what’s going on there?

    EB

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