Relay tester using a stand-alone independent operation, can also be connected to a laptop running the advanced structure. The host built a new generation of high-speed digital signal processor microcomputer, true 16-bit DAC module, a new modular high-fidelity high-power amplifier, comes with a large screen LCD display and flexible and convenient rotary mouse controller. Stand-alone operation is already very strong, can carry out most of the test, connected to the computer operation has a more powerful operating functions. AC voltage/current/inverse time limit current relay calibration: in the "variable test" software module, set Ua (or Uab)/Ia as the "fundamental" output, and set it to a certain initial value, set the step size, and then click "output incremental" with the mouse. "output increment", "output decrement" button or press the keyboard F5, F6 shortcut keys to add or subtract the voltage / current, measure the voltage / current / inverse time limit current relay action value and return value and action time and return time, calculate the return factor. 2. DC voltage/current relay calibration: in the "variable test" software module, set Ua (or Uab)/Ia as "DC" output, and set it to a certain initial value, set the step size, and then click "Output", "Increment", "Output", "Output", "Output", "Output", "Output", "Output", "Output", "Output", "Output", "Output", "Output", and so on. Incremental", "output decremental" button or press the keyboard F5, F6 shortcut keys to add or subtract voltage/current, measure the voltage/current relay action value and return value and action time and return time, and calculate the return coefficient. 3. Time relay calibration: in the "Variable test" software module, the time relay is calibrated to be "DC" output. In the software module of "Variable test", measure the action value, return value, action time and return time according to the test method of DC or AC voltage relay. 4. Power relay calibration: (1) Measurement of action area and sensitivity angle of power direction relay: In the software module of "Variable test", set Uab and Ia as rated values. Uab, Ia for the rated value, set Uab phase angle step, plus or minus the voltage phase angle, measured the action area on both sides of the boundary angle φ1, φ2, the sensitive angle φLM = 1/2 (φ1 + φ2).