Conditions and Phenomenon of Energy Meters’ No-load Behavior
When the energy meter has no-load behavior in operation, two conditions should be satisfied. (1) There should be no current in the current coil of the electricity meter; (2) the aluminum plate of the electricity meter should continuously rotate for more than a full circle.
The no-load behavior of the energy meter can only be determined if the above two conditions are met simultaneously. If the no-load behavior is caused beyond the range of 80% ~ 110% rated voltage, according to the relevant regulations, the electricity meter is qualified, which could not be regarded as no-load behavior; but when it comes to the users, as the electricity refund is concerned, obviously it should be regarded as no-load behavior instead of normal one.
In order to make a correct judgment, the analysis is made according to the above conditions:
I. There is no current in the current circuit of the electricity meter
First of all, the user does not use lighting, fans, TV and other household appliances, which does not mean that there is no current in the current circuit of the electricity meter. The reasons are as following:
1. Internal leakage
Due to disrepair, insulation damage of indoor wiring and other reasons, electricity linkage occurs on the ground and leakage current might make the meter work during closing time. This situation does not meet the condition (1), so it should not be considered as no-load behavior.
2. Take the sub-energy meter connected to the back of the master meter as an example. The ceiling fan without blade is mistakenly switched on in winter. Although there is no obvious electricity usage without noise and light, the electricity meter has been working with a load, and of course it cannot be regarded as no-load behavior.
Therefore, in order to determine whether the electricity energy meter itself is malfunction no-load working, the main switch at the electric energy meter terminal must be disconnected, and the phase line at the upper end of the main switch must be disconnected in some cases.
II. The electricity meter should not continuously rotate
After making sure that there is no current in the current circuit of the electricity meter, it can be determined whether it is no-load behavior or not based on the fact that whether the meter plate continuously rotates.
To judge continuous rotation is to observe through window whether the meter’s plate rotates more than twice. After confirming no-load behavior, note down the time t(minute) of each rotation and the constant c(r/kWh) of the electricity meter, and reimburse the electricity charge according to the following formula:
Refunded electricity: △A=(24-T) ×60×D/Ct
In the formula, T means daily electricity consumption time;
D means number of days of electricity meter no-load behavior.
If the no load direction is consistent with the rotating direction of the electricity meter, the electricity should be refunded; if the direction is opposite, the electricity should be replenished.
III. Other cases of electricity meter’s no-load behavior:
1. The current coil is short-circuiting due to overload and other reasons, and the voltage working magnetic flux is affected by this, which splits into two parts of flux in different space and different time, resulting in no-load working.
2. The three-phase active watt-hour meter is not installed according to the specified phase sequence. Generally, the three-phase meter should be installed according to the positive phase sequence or the required phase sequence. If the actual installation is not carried out according to the requirements, some energy meters mutually interfered seriously by the electromagnetic will sometimes perform no-load behavior, but it can be eliminated after correcting the phase sequence.
In short, once the no-load behavior occurs, it is not only necessary to check the situation of the electricity meter itself, but also sometimes check the wiring and other metering devices.
Post time: Feb-02-2021