Electronic instrument transformer is a kind of power distribution device

is composed of one or more voltage or current sensors connected to the transmission system and secondary converter

which transmits values proportional to the measured physical quantity to instruments

relay protection or control devices. A group of electronic instrument transformers share a set of merging communication unit. The merging communication unit will combine the current and/or voltage sampling data of the transmission section with the sampling time

and continuously send it to Ethernet in the form of data frames in accordance with the agreed communication protocol. When evaluating a certain type of electronic instrument transformer based on the radiation emission test specified in the GB/T 20840.8—2007 standard

it is found that its merging communication unit has electromagnetic radiation interference exceeding the standard. By analyzing the causes of interference due to excessive frequency points

the product circuit is improved by using the clock spread spectrum technology and the problem is solved. Meanwhile

such solution as the use of clock spread spectrum technology to suppress high-frequency radiation interference is obtained.