Circuit principle of three-phase protection relay test set (also called microcomputer relay protection tester):

1. The input AC220V power supply enters the input end of the double carbon brush voltage regulator T1 through the output control relay K1 through the fuse, and the electric quantity regulated by the large knob T1 enters the isolation transformer T2 (part-time current riser). The current riser is divided into three taps for output, one of which is ac0-250v output and the rated current is 3a. The output voltage of the taps can output 0-350v DC voltage after rectification and filtering. The second tap is 15V (10a). The tap outputs 0-10a AC current through the control of the sensor through the relay, 0-500ma AC current through the resistance, 0-10a or 0-500ma DC current through the relay conversion, and the second tap is 10V (100a) high current terminal. The tap directly outputs 100A current through the primary side of the sensor. The circuit has strong load capacity, However, the output is slightly overloaded and cannot be in the state of high current for a long time.

The auxiliary circuit of the three-phase relay protection test instrument is the same as the main circuit. The AC220V power supply enters the voltage regulated by the T1 small knob of the double carbon brush voltage regulator through the fuse. The output voltage of 0-20V or 0-250V AC or 0-350v DC can be directly adjusted through the isolation transformer T4. The rated current of this circuit is 1a. Press the "output control" switch of the secondary circuit. Adjust the small knob to output.

2. Measuring Circuit

The output of main circuit regulated by large knob is AC "0-250V", "0-500ma", "0-10a", "0-100A". DC "0-350v", "0-500ma", "0-10a" are converted through relay on circuit board in the equipment. Each time a file is switched, the memo can monitor the corresponding output. The "0-500ma" file is included in the "0-10a" file. When used, it is "0-500ma" monitoring under "0-10a".

3. Time Measurement

The device is equipped with a 6-digit display stopwatch. The electric stopwatch can be started internally or externally. When it is started internally, press the "output control" switch to start the stopwatch. Short circuit the stopwatch terminal on the device panel through the contact to stop the stopwatch. The stopwatch is equipped with a separate power switch, which can be turned off when it is not in use.

4. Acousto opticcue

The circuit equipment has a built-in acousto-optic prompt circuit. When the contact of the tested electrical apparatus acts, the contact can be connected to the acousto-optic prompt jack of the test box. Alarm sound or light will be sent out in the test box to indicate the action of the breaker contact.