The microcomputer relay protection test device is a new type of intelligent test instrument. The previous relay protection test tools were mainly composed of voltage regulators and phase shifters, which were bulky and had low accuracy, and could no longer meet the calibration work of modern microcomputer relay protection. With the continuous development of science and technology, microcomputer relay protection has been widely used in various fields such as line protection, main transformer differential protection, excitation control, etc. Substation comprehensive automation has become the mainstream. Modern microcomputer relay protection test devices can be divided into two forms: one uses traditional OCL power amplifiers, which are large in size and weigh about 25Kg, relatively bulky. The power amplifier tubes operate in the amplification region and are prone to damage over time, with a narrow dynamic range and low accuracy. The other uses switching power supplies and digital power amplifiers, which are small in size, light in weight, and high in efficiency, representing the development direction of relay protection test devices. It can test various types of relays such as voltage, current, frequency, power, impedance, harmonics, differential, and synchronization relays manually or automatically. It can simulate various fault types for distance and zero-sequence protection device calibration and complete group testing of protection devices. It can automatically scan the ratio braking curves of microcomputer and digital transformers and generator-transformer unit differential protection, and has GPS trigger function. The microcomputer-based relay protection test device is an important test tool to ensure the safe and reliable operation of the power system. With the rapid development of computer technology, microelectronics technology, and power electronics technology, it is an inevitable trend of technological progress to continuously introduce new high-performance microcomputer relay protection test devices by applying the latest technological achievements. The relay protection test device is an important test tool to ensure the safe and reliable operation of the power system. With the continuous expansion of the modern power system scale and the increasing requirements for reliability and efficiency in power system operation and management, the testing work of relay protection personnel has become more frequent and complex. Today, with the rapid development of computer technology, microelectronics technology, and power electronics technology, it is an inevitable trend of technological progress to continuously introduce new high-performance relay protection test devices by applying the latest technological achievements, and it is also our responsibility given by the times. The relay protection test device is a new type of miniaturized microcomputer relay protection test device implemented by fully utilizing modern advanced microelectronics technology and devices, based on the reference to the People's Republic of China electric power industry standard "Technical Conditions for Microcomputer-based Relay Protection Test Devices" (DL/T 624 ─ 1997). It adopts an advanced structure that can operate independently as a single unit or connect to other computers for operation. The host has a built-in high-performance industrial computer and high-speed digital signal processor, true 16-bit DAC module, new modular high-fidelity high-power amplifier, and comes with a TFT true color LCD display and embedded microcomputer keyboard. It can be operated independently as a single unit or connected to a laptop computer for operation. It has powerful operation functions, small size, and high accuracy. It not only has the superior performance and advanced functions of large test instruments, but also has the compactness, flexibility, ease of operation, and high reliability of small test instruments.