Analysis of Issues and Causes in Smart Meter Testing

1. Issues and Cause Analysis in Smart Electricity Meter Testing

During the verification of smart electricity meters, inspections must be conducted on the meter’s appearance, as well as the clarity and integrity of nameplate markings. Additionally, careful checks are required for physical damage and whether the display can show digits completely. A power-on inspection is also necessary. If error codes appear on the display after power-up, faults should be identified and addressed according to the specific error code. Typically, if the code “ERR-04” appears, it indicates insufficient battery power within the smart meter, requiring battery replacement. If the code “ERR-08” appears, it signifies a clock fault, necessitating time calibration of the meter.

1.2 Basic Verification Item Testing

(1) Before conducting basic verification tests, load points in the test setup are typically tested first, with specific actions taken based on the verifier’s alarm status. A voltage alarm requires checking the voltage amplifier, while a current alarm requires using the verification device to check whether the current pins and meter sockets are securely connected and whether an open circuit exists. If neither voltage nor current issues are found but the alarm persists, a multimeter should be used to measure continuity and locate any open circuits in the meter.

(2) During verification, frequently switching current ranges and magnitudes may trigger verifier alarms. In such cases, the device power should be turned off. After the power switch indicator light completely extinguishes, the switch should be turned back on to re-establish connection with the computer.

(3) After powering on the smart meter, if no response occurs after eliminating open circuits and verifier faults, the issue is usually due to loose or broken sampling wires, fractured voltage-divider resistors, damaged optocouplers, poorly soldered components on the PCB, or burned-out meter components. These potential causes should be checked to identify and resolve the fault.

(4) During the start-up test, under rated voltage, rated frequency, and COSφ=1 conditions, once the load current reaches the specified starting current value, the meter should produce a pulse output or cause the energy output indicator light to flash within the calculated start-up time. If there is no output, first check whether the current pins are securely connected and rule out open circuits in the meter; otherwise, the fault may be due to internal component failure.

(5) During the creep test, the voltage applied to the meter should be 115% of the reference voltage. If the smart meter fails the creep test, it is likely due to internal component failure, and the meter should be returned to the manufacturer for repair.

(6) If a batch fails during the meter constant test, consider whether the energy increment setting is too small. The increment can be appropriately increased within the range permitted by regulations before retesting.

1.3 Multi-Function Item Testing

(1) For failed tests such as 485 communication or daily timing, check whether the terminal pins on the verifier and the meter sockets are securely connected. For wired verification setups, check whether pulse lines are unclipped, incorrectly clipped, or have loose solder joints. A multimeter can also be used to measure circuit continuity.

(2) If a batch fails the 485 communication test, check whether the communication protocol and baud rate are correctly configured.

(3) If no daily timing pulse is generated during the daily timing test, first check whether the screw on the multi-function pulse output terminal is loose or whether the daily timing pulse output circuit is faulty. Inspect the daily timing circuit for loose or bridged solder joints. If the meter uses an external clock chip for timekeeping, directly measure whether the clock output frequency is out of tolerance.

(4) If time calibration or zero-reset tests fail, verify whether the multifunction configuration address in the verification software matches the address on the meter’s nameplate. If not, re-perform automatic address reading in the pre-inspection step. Also, check whether the meter’s programming button is enabled. If disabled, time calibration and zero-reset will fail.

1.4 Key Downloading

During key downloading, if an authentication error occurs, first check whether the encryption dongle is reliably connected, then verify the correctness of the encryption machine’s IP address and password. For failed remote key updates, check whether the key port configuration is correct and whether the server listed in the system configuration is correct. If an operation error during download causes the meter to lock internally, stop the test and wait 24 hours before attempting the download again. If it still fails, contact the manufacturer for assistance.

1.5 Remote Fee Control

Failure in remote fee control, where the smart meter fails to trip or cannot close after tripping during trip/close tests, is likely due to faults in the meter’s trip/close control circuit or internal relay. Control circuit faults are primarily caused by high temperatures or strong mechanical impacts, leading to loosened structural components and shifted moving parts, resulting in failed relay engagement or release. Over time, this can cause poor soldering in the control circuit components.

2. Precautions for Smart Electricity Meter Testing

2.1 Strengthen Quality Supervision of Smart Electricity Meters
During meter testing, the verification environment must be evaluated to ensure that factors such as magnetic fields, humidity, and temperature meet testing requirements. For meters with issues during testing, the fault cause must be promptly identified and addressed; irreparable meters should be returned to the factory. A quality supervision system should be established based on verification procedures to enable full-process quality tracking. For meters that pass testing and are installed on-site, periodic random inspections should be conducted, with results promptly reported. Faulty meters must be handled immediately, while qualified ones require ongoing quality monitoring to ensure safe and reliable operation.

2.2 Strengthen Testing of Smart Meter Bidirectional Communication Function
Smart meters typically have bidirectional communication capabilities, enabling data collection and transmission with the power grid, sending power usage information to smart substations, and receiving control commands from them. Therefore, the bidirectional communication function must be tested before deployment. Additionally, performance tests beyond the communication module should be conducted to ensure the meter’s overall excellent performance.

2.3 Strengthen Computer Software Management
Smart meter verification, testing, and key downloading rely on software and are controlled via computers. Software failures can significantly impact work progress. Therefore, data should be saved immediately after testing to enable quick file recovery and restore normal software operation in case of errors. During key downloading, avoid arbitrarily changing serial ports to prevent communication failures.