In the case of mass-produced electricity meters which have received the type approval (refer to the next paragraph), many of the required tests are skipped and their verification largely depends on the results of several tests, including the error test. The meters passing these tests are sealed by sealing cap indicating the validity period. When an electricity meter is used in combination with an instrument transformer, the verification of the meter and inspection of the transformer and the combined performance of the meter with the transformer are conducted. If the combined unit passes the verification/inspection, the unit is sealed with a verification tag and a combined number tag.
Next figure shows the verification (in case of direct connected meters) flow chart. In case of transformer operated meters, transformers are inspected.
Verification Flow Chart
The following table shows the validity term of the meter that passes the verification.
|kind of meter||nominal current (A)||validity period (year)|
|direct connected meter||normal meter||20
7(electro mechanical meter)
|transformer operated meter||normal meter
high precision meter
5(electro mechanical meter)
nominal current equal Imax