Design and Application of Mobile Testing Laboratory for Current Transformer

In response to the growing requirements of on-site calibration test of transformers in power system, a mobile testing laboratory for current transformer was designed, based on the comparative measurement stipulated by the national verification procedures. Mounted in the industrial container, the mobile laboratory includes various instruments and equipments used in the test. Compared with traditional methods, the laboratory overcomes lots of shortcomings, such as carrying equipments hard, wiring complexity and so on. It is easy to carry out experiments just by providing power supply, primary side and secondary side wiring. The application results showed that the mobile laboratory was simple, convenient, stable and reliable, significantly reducing the labor intensity of workers and improving work efficiency. Introduction With the rapid development of the power system, the number of metering transforms used in the power grid increased. The measurement error of transformers, which relates to energy metering and trade settlement, belongs to the state compulsory verification project. Therefore, the efficiency of verification measurement for transformers attracts more and more attention. In accordance with the regulation [1], a large amount of testing equipment is needed in the on-site testing of current transformers, such as standard current transformers, voltage regulators and so on. When the current is greater than 2000A, the power capacity doubled. In that case, the equipment is too heavy to move, and the connection is difficult, leading to great inconvenience during on-site testing. Nowadays, the measuring cars and mobile testing devices for transformers have been a hot topic, because of multi-functions and convenient application [2-5]. According to the actual work needs, this work designed a mobile testing laboratory for on-site verification of current transformer, based on the principle of comparative method. All testing equipments were installed in a container, what is convenient to connect. The system is capable of measuring errors of current transformers, whose greatest rated current is 5000A, and highest degree of accuracy is 0.1. It overcomes many disadvantages of the traditional testing method, for example, moving devices hard, wiring in disorder et al. The laboratory is simple to operate and transport, which not only improve the work efficiency significantly, but also ensure safety of stuffs and equipments, and reduce outage time for maintenance.