Development Of CAT Test-bed For High-low Pressure Relay

High-low pressure relay is a kind of pressure protector, which can integrate the control of low pressure and the protection of high pressure. In order to make sure that Train Air Condition Unit can be running safely, we should check and adjust pressure relay on a regular time. According to the request for testing, the development of CAT test-bed for high-low pressure relay of Train Air Condition Unit is presented, including the theory and method of testing, the composition of hydraulic system and CAT system, the design of hardware and software ,the error analysis of testing system and so on . Firstly, This paper introduces the development of Computer Aided Testing and the pivotal knowledge of CAT, then introduces the structure and working theory of pressure relay. According to the request for testing , the scheme of test-bed is present, including the design and simulation of hydraulic system ,the design of CAT system's hardware and software .To enhance the stability and reliability of testing system ,many measures are taken to eliminate interfere, Finally ,The paper present the testing result and the error analysis of testing system .The result shows the test-bed can fully satisfy the requirements of consumer, not only realizing automation of testing ,but also improving testing precision, extending testing range and reducing the cost of testing. It can provide scientific, reliable and automatic methods for the testing and checking of these pressure relays, and can meet the need of use and service of trains in our country.