Open and Close Link Testing in Energy Meters

What does it say in the test protocol? Where is the boundary between a pass condition and a fail condition? What were the equipment manufacturer's recommendations upon asking these questions over the telephone?

Good answer and good link. My experience with energy meters ended with the end of electro-mechanical meters and was primarily with single phase meters.

Hi @RAMConsult, Thank you for answering my question and also for providing the link for the paper explaining further the difference and importance of open and close link testing. As i understand form the discussion here basically the difference of open and close link testing are: (correct me if i am wrong or if a missed something)

• Testing at Open link, current coil is only considered and energized since the voltage coil is isolated from the former.
• Testing at Close link means that both the current and voltage source are being energized. Since at nominal or normal conditions at site, this two coils are obviously energized hence when we talk of Close link testing we can simply generalized that is conducted on site or even in laboratories / meter shop but simply both the v and i coils are energized.
• Lastly since there are so many meter forms, the user will want to familiarize with those forms as to test meters more efficiently and of course meter base should be considered as they are different from each other.

I want to thank PWSlack, gringogreg and RamConsult for the answers that you've provided here.

The function of the link is to isolate the two coils for the sole purpose of minimizing the effect of their combined burden on the test-set power source and its subsequent effect upon accuracy as the number of DUTs (Device Under Test) increases.

You should ponder what happens if only the current coil is energized; i.e., how much will a kWhr meter read if the voltage input is zero? Now look at your first two bullet points and examine your logic.

@RAMConsult, Thank you for your answer, Yes as for the first bullet i've mentioned if only the current source is energized. As per gringogreg "This allows the current circuit to be energized at a much lower voltage (usually 6 v) supplied by the test panel, while maintaining the nominal voltage to the potential circuit" I'm very confuse with this since all equipment has a certain burden that needs to be satisfied in order for the device itself to run. Question is i thought that the voltage will be isolated hence it will not be energized but it says there that it will maintain the nominal voltage to the potential circuit. Please advise