Use and precautions of DC resistance tester

Transformer DC resistance tester working principle block diagram. It is mainly composed of constant current power supply, discharge circuit, amplification and analog-to-digital conversion circuit, computer, printer, display, and buttons. R is measured as the DC resistance of the winding. R is marked as the known internal current sampling resistor. Connect the AC220V power cord, turn on the power switch, and connect the power supply line and measurement line. After the system is turned on and enters the initial state, you can press the "Select" key to select the required power supply current. Press the "Select" key to cycle through the selection.

After the displayed data is stable, if you need to print the data, press and hold the "Print" key and the printer will print out the measurement results. This key is a scan key. If you click it once, the printer may not work: long press may print multiple times: press this key until the printer starts to print, and immediately lift it up to complete the printing. When the power indicator light on the printer panel goes out, the printer does not print.

For the longitudinal test of the on-load tap-changing transformer, it can be completed with one power supply. The instrument program design allows the switch to be inverted to the next tap after a certain tap is measured. Then press the "Confirm" key. The display screen displays "30002" and the instrument will enter the next tap measurement.

For no-load voltage-regulating transformers, after a tap test is completed, the "reset" key needs to be pressed, and the system is in the discharge state. The "current indication" meter head gradually returns to zero, the "discharge indicator light" goes out, and the motor test discharge sound ends, indicating the end of discharge. Only after the discharge is completed can the switch be reversed, or an external short-circuit switch can be connected to speed up the discharge process, and then the "confirm" key is pressed for the next measurement. After

the test is completed, press the "reset" key, the instrument power supply will be disconnected from the winding, and the "discharge indicator light" will light up, the discharge sound alarm will sound, and the "current indication" meter head will gradually return to zero, indicating that the winding is in the discharge state. At this time, the instrument returns to the initial state and the required current can be selected. After the "current indication" meter head returns to zero, the "discharge indicator light" goes out, and the discharge sound ends, the connection can be reconnected, and the "confirm" key is pressed for the next measurement.

Instrument shutdown: After the instrument is reset, it is in the current selection state, and the power supply can be turned off. Please turn off the instrument after the "current indication" meter head returns to zero, the "discharge indicator light" goes out, and the discharge sound ends, and then remove the power supply line and measurement line.

When measuring the windings of the same transformer and the same motor test system voltage level, the same current should be selected for testing to avoid system errors. Generally speaking, the larger the transformer capacity, the smaller the resistance value of the winding, and the larger the selected test current should be. If the range allows, it is best to use 10A or 20A current for high-voltage winding measurement and 20A or 40A current for low-voltage winding measurement.

After pressing the "Confirm" key, the instrument supplies power to the winding and the test process begins. The "current indication" head gradually deflects to indicate the selected power supply current, and the display screen displays in sequence: "30001": indicates automatic zero correction; "30002": Difficulties and challenges faced by RFID protocol consistency test system to determine whether charging is complete and enter the steady current state; "30003": Automatic range selection according to the size of the test signal. After the selection is completed, the measured resistance value is displayed. During the test, if "10000" appears on the display, it means the instrument is in under-range state; if "20000" or "30002" appears and remains stationary and the ammeter indication does not reach the nominal current, it means the instrument is in over-range state.