Test equipment for type B residual currentdevices based on direct digital synthesizer
                                         DU Liang1,2, XIE Zhenghua1,2, WANG Yao3,4, SHI Shunquan5,WANG Tianshuo3,4
(1.Zhejiang Testing & Inspection Institute For Mechanical And Electrical Products Quality, Hangzhou 310051,China; 2.Zhejiang Institute of Mechanical & Electrical Engineering Co., Ltd., Hangzhou 310051,China;3.State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University ofTechnology, Tianjin 300130,China; 4.Key Laboratory of Electromagnetic Field and ElectricalApparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300130, China;5.Arbin Instruments (Tianjin) Co., Ltd., Tianjin 300401, China)

Abstract: Aiming at the issue of less adaptability of conventional test equipment for type B residual current device, a direct digital synthesizer (DDS) based test equipment was put forward according to the test requirement. Arbitrary waveforms of residual current could be generated accurately benefit from the welldesigned DDS signal generator, which was controlled by DSP and FPGA microcontrollers. In order to stabilize the output current, a PID based feedback control strategy was introduced. The results indicate that the test equipment can output arbitrary residual current with a frequency bandwidth of 1 kHz ,and current range of 0~30 A, so as to meet the requirements of the relevant standards for residual current device.

Key words: residual current protection; test method; arbitrary waveform constant current technology; direct digital synthesizer (DDS)