In order to protect the utility revenue it's essential to do regular on-site tests on meter installations. If you are suffering huge losses you should focus on transformer operated meters first.
Those meter installations can be faulty at different points:
the instrument transformer ratio does not match with the meter typical mistake is a wrong programmed meter the fault can be figured out by checking the meter accuracy on the primary side
the burden of the instrument transformer does not match with the installation typical mistakes are: - wiring is too long or wrong cross section - a backup meter is installed and overburdens the installation the fault can be figured out by doing a burden measurement
the instrument transformers have a ratio- or phase displacement error the fault can be figured out by doing a instrument transformer test
The meter accuracy is out of range Old electromechanical meters (ferraris meters) have worn-out uper and lower bearings. If you hear a scratching sound coming from the rotating disc it's likely possible that the meter is running too slow.
wrong installation (tamper or mistake of the installer) This is the part I saw most often. Let's take a closer look on this.
In our example we have a three-phase four wire CT-operated meter 2500/5 A, like it's installed in shopping malls and for small industry. We assume that the consumption is equal to the nominal load.
The wiring looks like this:
What happens when by mistake an instrument transformer for one phase is reversed?
We see that this simple mistake is causing a loss of 66%. Or in terms of money 165,600US$ per month. (20ct/kWh) In Germany the utilities are inspecting CT installations every 6 months. CT/PT installations are inspected every 3 months.
The real loss reduction does mainly comes mainly from good maintenance of the transformer operated metering installations.
What is your experience with on-site test of energy meters? Leave us a comment below or use our contact form. Thank you for reading.
Cyberattacks against critical infrastructure have become common. This time, a ransomware infection has been reported on the systems of City Power, one of South Africa’s leading power suppliers, specifically in the capital, Johannesburg. The incident left thousands of residents without electric power.
City Power provides a prepaid electricity distribution service for local residents and companies. According to the company’s report, the encryption malware blocked access to databases, internal networks, web applications and the official City Power site.
The infection was detected Wednesday (25.07.2019) night. The incident has prevented citizens from accessing the company’s prepaid services. In addition, entrepreneurs who produce energy from solar panels and then sell it to the company have also been disrupted.
City Power Twitter notification:
City Power has been hit by a Ransomware virus. it has encrypted all our databases, applications and network. Currently our ICT department is cleaning and rebuilding all impacted applications.^GR — @CityPowerJhb (@CityPowerJhb) July 25, 2019
Customers may not be able to visit our website and may not be able to buy electricity units until our ICT department has sorted the matter out, Customers and stakeholders will be updated as and when new information becomes available^GR — @CityPowerJhb (@CityPowerJhb) July 25, 2019
CityPower was luckily able to restore their systems from backups on Friday, Jul27 without paying a ransom.
If you have questions on our AMI and prepayment vending security measures, please let us know. It’s good that CityPower was able to restore the operations within 48 hours. It’s better to avoid a server infection.