One. Functions of ordinary household electric meters
Household kWh meter is all active watt-hour meters. They record the active energy consumed by electrical appliances. Reactive energy is not recorded. Only active energy is consumed by heating elements such as ordinary bulbs and electric furnaces. On some inductive or capacitive loads (motors, TV sets, air conditioners, fluorescent lamps, etc.), except active energy is consumed. There is also the consumption of reactive power.
The actual electric energy consumed by inductive load is the vector sum of active and reactive electric energy. The difference between them is 90 degrees. The actual electric energy consumed is certainly greater than the electric energy recorded by the kWh meter.
But the power consumed on the inductance load is 100% recorded on the kWh meter, it is impossible to reduce the active power consumption by parallel connection of any electrical load.
Reactive power consumed by inductive load can be compensated by parallel corresponding inductors, but this is meaningless for household watt-hour meters which only record active power.
Therefore, to reduce the active power through external electrical appliances can only be a trick, unless usually pay more attention to saving electricity.
IC card ammeter is composed of base meter, MCU chip, digital display, relay switch, ESAM module and IC card interface.


Two. System composition of household Electric meter
The general household meter consists of two systems: the measuring system and the singlechip processing system.

Measurement system: a single-phase electronic watt hour meter.

Working principle: Voltage sampling is completed by voltage divider, current sampling is completed by sampling resistance, voltage and current signal after sampling is converted from multiplier to power signal, after V / T transformation, the meter is driven to work, and pulse signal is input into the single chip microcomputer system.

Users need to pay in the power supply department to buy electricity. The amount of electricity purchased is written into the user's electric card on the motor sold. The electric card is passed to the meter. The electric card can be encrypted many times to ensure the user can use it reliably. When the electricity consumption is exhausted, the relay in the table will automatically cut off the power supply circuit.

Three. Installation of Electric meter
The meter should be installed on the wall or on the switch board which is not easily affected by vibration, and the distance from the ground should be between 1.7 and 2 meters.
The place where the ammeter is installed should be clean, dry, no strong magnetic field, and as far as possible in obvious places for reading and monitoring;
The meter should be installed in the box where there is mechanical damage and dirty and easy to touch.
The meter should be installed vertically, with tolerances not exceeding 2 degrees.

Four. Check the electricity of the Electric meter
Power on to check whether the meter is working normally. If there are abnormal phenomena such as not turning, reversing and excessive errors, we should analyze the reasons and eliminate them. Most of the causes of these failures are wiring errors. The cause of the inversion is not only the reversal of the voltage and current coil polarity, but also the load abnormality. For example, in the load of three-phase active power meter, when the larger capacity of the motor overspeed, the motor becomes a generator operation, then the active power meter will be reversed.