Comparison between direct-connection electric meters and mutual inductance electric meters

Direct-connection meter and mutual inductance meter are two common types of meters. The following are their main differences:

1. Measurement principle

Direct-connection type: The current is directly fed into the meter for measurement, without the need for a mutual inductor, and the electric energy is directly measured through internal components.

Mutual inductance type: With the help of a current transformer, the large current on the primary side is proportionally converted into a small current on the secondary side and then input into the meter for measurement.

2. Applicable scenarios

Direct-connection type: Suitable for small current scenarios such as homes and small appliances. The rated current of single-phase meters is mostly 5A and 10A, and the rated current of three-phase meters is generally ≤100A.

Mutual inductance type: Used in large current scenarios such as industrial equipment and large motors. Currents of hundreds to thousands of amperes can be measured through mutual inductors of different ratios.

3. Range

Direct-connection type: The range is narrow, usually not exceeding 100A.

Mutual inductance type: The range is wide, and it can cover 0.5A-5000A with different mutual inductors.​

4.afety​

Direct connection: direct contact with high-voltage lines, there are safety risks such as electric shock and short circuit. ​

Mutual inductance: The mutual inductor realizes electromagnetic isolation, the meter is separated from the high-voltage line, the secondary current is ≤5A, there is no risk of electric shock, and it can also prevent surge damage to the equipment. ​

5. installation complexity​

Direct connection: simple installation, just connect the incoming and outgoing lines directly.

Mutual inductance: the current transformer must be installed first, and then the secondary signal line is connected, the process is more complicated. ​

6.cost​

Direct connection: simple structure, no mutual inductor required, low cost. ​

Mutual inductance: mutual inductor is required, the equipment cost is high, but the comprehensive cost may be lower in high current scenarios, and the measurement accuracy and safety are better.

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