1Dual channel DC resistance testerOperation guide:

1. Connect the AC220V power cord, turn on the power switch, and connect the power supply line and measurement line.
After the system starts up and enters the initial state, you can press the "Select/Print" button to select the required power supply current.

Press the 'Select/Print' button to cycle through selections.
When measuring various windings of the same transformer at the same voltage level, the same current should be selected for testing to avoid system errors. Generally speaking, the larger the capacity of the transformer, the smaller the resistance value of the winding, and the larger the selected test current should be. If the range allows, 10A or 20A current should be used for high-voltage winding measurement, and 20A or 40A current should be used for low-voltage winding measurement.
After pressing the "confirm" button, the instrument supplies power to the winding and the testing process begins.
The "current indicator" header gradually deflects to indicate the selected power supply current, and the display screen sequentially shows: "30001": indicating automatic zero point correction; 30002 ": Determine whether the charging is completed and enters a steady current state; 30003 ": Automatically select the measurement range based on the size of the test signal. Selection completed, display the measured resistance value. During the testing process, if the display screen shows "10000", it indicates that the instrument is in an under range state; If "20000" or "30002" remains stationary and the ammeter reading does not reach the nominal current, it indicates that the instrument is in an over range state.
If the CH1 indicator light is on, the display screen will show the resistance value of channel 1 (V1+, V1-); If the CH2 indicator light is on, the display screen will show the resistance value of 2 channels (V2+, V2-). During the testing process, if the "Channel" button is pressed to perform channel conversion, the display screen will show "H - ----", indicating the start of the conversion. The unit of display value on the screen is "m Ω".
After the display data is stable, if you need to print the data, press and hold the "Select/Print" button to print the measurement results. When in the 1-channel state, print the 1-channel resistance value R1, and when in the 2-channel state, print the 2-channel resistance value R2. This key is a scan key. If clicked once, the printer may not function. Long press may print multiple times. Press this key until the printer starts printing and immediately lifts it to complete the printing. When the power indicator light on the printer panel is off, the printer does not print.
6. For longitudinal testing of on load tap changers, it can be completed with one power supply. The instrument program design allows the switch to be inverted for the next tap after a certain tap has been tested. Then press the "confirm" button and the display screen will show "30002", and the instrument will enter the next tap measurement.
7. For no-load tap changers, after a certain tap test is completed, the system needs to be in a discharge state by pressing the "reset" button. The "current indicator" gauge gradually returns to zero, the "discharge indicator light" goes out, and the discharge sound ends, indicating the end of discharge. After the discharge is completed, the switch can be switched or an external short-circuit switch can be connected to accelerate the discharge process, and then press the "confirm" button for the next measurement.
After the test is completed, press the "reset" button to disconnect the instrument power supply from the winding. At the same time, the "discharge indicator light" will light up, the discharge sound alarm will sound, and the "current indicator" meter will gradually return to zero, indicating that the winding is in a discharge state. At this point, the instrument returns to its initial state and can continue to select the required current. Wait for the "current indicator" to return to zero, the "discharge indicator light" to turn off, and the discharge sound to end before rewiring, and press the "confirm" button for the next measurement.
9. Shutdown: After resetting the instrument to the current selection state, the power can be turned off. Please reset the "current indicator" to zero, turn off the "discharge indicator light", turn off the discharge speaker, and then remove the power supply and measurement lines.
10. Printer paper loading:
(1) Turn off the power, remove the printer cover, pinch the movable tongues on both sides of the printer inward with your fingers, and pull the printer out of the panel.
(2) Insert the paper roll onto the paper shaft and push it into the normal position along the direction of the shaft groove.
(3) Press the power button, press the SEL button to turn off the indicator light, and then press the LF button to start the machine head moving. Send the printing paper into the entrance of the machine head until a certain length of paper head is exposed.
(4) Insert the printer into the panel, extract the printing paper from the paper outlet of the printer cover, and cover the printer cover.
IIDual channel DC resistance testerNotes:
If the instrument malfunctions or starts incorrectly, the testing process should be terminated by pressing the "reset" button to initialize the system. During the reset, the LCD displays "00000", and after a few seconds, the current value is displayed.
When the instrument is in testing mode, the power must not be turned off without resetting.
Although there is a discharge protection circuit in the instrument, abnormal situations such as power line disconnection and power outage should be avoided during the testing process.
When testing the no-load voltage regulating winding, unless there is a short-circuit switch, it is not allowed to switch the switch before the discharge is completed.