Does a smart meter require an external power cord?

Most smart meters do not require an external power cord, but are designed with a built-in power supply or draw power from the grid to achieve self-sufficiency. However, some high-end models or special scenarios still require an external power supply to ensure stable operation. The specific analysis is as follows:

1、 Mainstream design: Built in power supply or grid power supply

Built in battery/supercapacitor

Many smart meters use built-in batteries or supercapacitors as backup power sources to ensure basic functions such as clock and data storage can still be maintained during power outages. For example, the built-in battery can support the meter to keep the clock running and key data not lost during power outages, while the supercapacitor can provide instantaneous energy during short-term power outages, ensuring data upload or relay action.

Directly obtaining electricity from the power grid

Smart meters typically obtain energy from the power grid through voltage sampling circuits, such as high-precision voltage divider resistors or voltage transformers. This design does not require an external power cord and directly uses the grid voltage to proportionally reduce and supply power to the electricity meter. For example, an AC-DC power module may be used inside the electricity meter to convert 220V AC power into 5V or 12V DC power, providing stable power for microcontrollers, communication modules, etc.

2、 Applicable scenarios for external power supply

Although the built-in power supply design can meet most needs, the following scenarios may still require an external power supply:

High end models or special functional requirements

Some high-end smart meters may rely on external power sources to ensure stability due to the integration of more functions (such as 5G communication, big data analysis) or the need for continuous high-power operation. For example, an electricity meter that supports real-time bidirectional communication may require additional power support during peak data transmission periods.

Areas with unstable power grids

In areas with large voltage fluctuations or frequent power outages in the power grid, an external power source (such as an uninterruptible power supply (UPS)) can be used as a backup solution to ensure the continuous operation of the electricity meter and avoid data loss or measurement interruption.

Industrial or special environments

In industrial settings or extreme environments such as high temperature and humidity, external power sources may be more reliable and able to withstand the impact of harsh conditions on built-in batteries.

3、 Design advantages and considerations

Convenience and economy

The built-in power supply design reduces wiring costs and installation complexity, meeting the convenience and efficiency pursued by smart meters. For example, 4G smart meters can achieve remote communication without wiring by wirelessly connecting to the backend, further reducing dependence on external power sources.

Safety and reliability

External power sources may introduce wiring safety hazards such as short circuits and leakage, while built-in power sources or grid power supply designs enhance safety through isolation transformers, overvoltage protection, and other circuits. For example, lightning protection and overcurrent protection modules may be integrated inside the electricity meter to ensure safe operation even in the event of grid abnormalities.

Energy Efficiency and Environmental Protection

The built-in power supply design improves energy utilization efficiency through technologies such as energy recovery and power optimization. For example, some electricity meters use low-power chips and sleep mode to reduce energy consumption during standby and reduce the demand for external power sources.