Design Of New Type Electronic Overload Relay

With the rapid development of technology and application of electrical components in various fields deepening, people to protect motor in operation requirements are constantly improve, especially in the modernization, automation industry in the protection of the motor is particularly important, electrical components which requires the control of motor has multiple protection functions, which play a double sheet metal overload relay overload protection of poor accuracy, while the electronic overload relay control accuracy, in order to meet the needs of users of products control accuracy requirement, this paper developed the electronic overload relay is a kind of accurate control, high sensitivity.The electronic overload relay is developed in this paper is a kind of product without auxiliary power, at the same time with manual reset and automatic reset function.The product composed by the action mechanism, auxiliary contacts, current transformer, controlling and detecting unit and a shell part. Product is used digital sampling, MCU control. The product has the function of a power supply indicating, tripping indication, the test button, overload protection, phase failure protection and load unbalance protection function.Through the introduction of the working principle of action mechanism, This paper presents a method for realizing the control loop using electromagnetic theory of the normally open contact and the normally closed contact of conversion. This paper expounds two important task in designing auxiliary contact system, namely the contact pressure calculation and contact material selection. Through the design of hardware and software in controlling the detection unit, the article introduces the power generation, signal acquisition, signal processing and the process of how to make the control circuit to realize the overload protection, phase failure protection and automatic reset function.This paper expounds several important type tests, These tests must be carried out for obtaining the national mandatory product certification. Comprises a switch auxiliary contacts and breaking capacity, limiting the short-circuit current capacity test, product electromagnetic compatibility test and operation characteristics test. The paper analyzed the factors affecting the test result and Methods to improve.