With the rapid development of China’s economy and society, both residential and commercial electricity consumption has increased dramatically. Traditional power grid collection systems are no longer able to meet the demand, leading to the emergence of new smart metering systems. The meter concentrator, also known as the smart meter data concentrator, plays a crucial role in the bidirectional communication of smart metering systems.
Meter Concentrator
The meter concentrator consists of seven units: power supply unit, storage unit, RTC (Real-Time Clock), MCU (Microcontroller Unit), display unit, downstream communication interface, and upstream communication interface. The power supply unit is responsible for system power supply, the storage unit records information, the downstream communication interface communicates with the next-level meter concentrator or meter, the upstream communication interface communicates with the previous-level meter concentrator or master station, the display unit is used for signal input and information display, and the RTC provides accurate time and control information for data collection, exchange, and system operation.
Principle block diagram of the meter concentrator
Requirements for RTC in the Meter Concentrator
The meter concentrator has strict requirements for RTC due to its outdoor nature and the need for time accuracy and operating temperature range. According to the accuracy requirements of the State Grid Corporation of China and the China Southern Power Grid: at the reference temperature, the accuracy of internal clock (if any) should be better than ±0.5s/24h [1] [2], which means that RTC should have an accuracy better than ±5.79ppm at the reference temperature. In the temperature range of -25℃ to +55℃, the temperature coefficient of accuracy for internal clock (if any) should be better than 0.1s/℃/24h, which corresponds to a precision better than ±1s/24h[1] for the internal clock within this temperature range, equivalent to a precision better than ±11.57ppm for the RTC.
RTC INS5699C
The INS5699C RTC developed by DAPU is capable of maintaining a high accuracy of ±3.4ppm and high stability in a temperature range of -40°C to +85°C. It has passed multiple tests and is known for its high precision, wide temperature range, high stability, and reliability. Its excellent stability meets the timing requirements of power products, especially meter concentrators, and fully meets the stringent standards of the power industry.
INS5699C Temperature Stability Test
Standard Test Requirements vs INS5699C Test Results
The INS5699C incorporates a 32.768KHz TCXO (Temperature-Compensated Crystal Oscillator) with temperature compensation function. It supports dual power supply with a voltage range of 1.6V to 5.5V. Under typical 3V power supply conditions, it has a rated current of only 1.0uA, resulting in very low power consumption. It has a storage temperature range of -55℃ to +125℃ and an operating temperature range of -40℃ to +85℃, ensuring normal and stable operation in extreme temperature environments. What’s more, it adopts SMD3225 package, which is small in size and convenient for PCB layout and wiring in concentrators.
The INS5699C provides various functions such as calendar, clock, counter, alarm, timer, interrupt, etc., and can also serve as a TCXO 32.768KHz frequency source output for the expansion function application of concentrator systems.
DAPU’s RTC series products have been tested and certified by several leading customers in various industries and have been successfully applied in these fields with excellent performance. The successful application of INS5699C in meter concentrators once again demonstrates DAPU’s strength in chip R&D. Moreover, DAPU has launched a full range of RTC products that can fully meet different requirements in multiple domains and scenarios.
In the future, DAPU will continue to leverage its technical advantages and stable supply chain system to introduce more high-performance, high-reliability, and cost-effective RTC products, enriching the domestic chip market and better serving its partners, making greater contributions to the development of the chip industry.
[Notes]
[1] General requirements, tests, and test conditions for AC electrical measuring instruments - Part 11: Measuring instruments - National Standard of the People’s Republic of China (GB/T 17215.211-2021)
[2] Technical requirements for type II concentrators of low-voltage power user centralized meter reading system (2016 edition) - The China Southern Power Grid.