ST-3000 Intelligent Cable Fault Tester Operation Menu Introduction
After power-on and reset, the first screen displayed is the copyright logo, as shown in Figure (6)
Schematic diagram of the power-on state.
When the year, month, and day are entered sequentially, it automatically enters the second screen, or press "Reset" to directly enter the work selection menu.
"Work Selection" menu
"Pulse" mode menu: select 1 from the main menu to enter the pulse menu.
Select according to actual testing needs by pressing keys.
3. Introduction to the main test display interface
The main interface is divided into three areas. The upper area is for calculation parameters and results, as shown in Figure (7).
The middle area is for waveform display (before sampling, it shows the wiring diagram). One or two waveforms can be displayed as needed. Vertical cursor lines and time scales are also displayed.
The lower area is for status and date display. The status displays are: pulse direct flash, surge 1, surge 2. In pulse mode for measuring full length and fault, it prompts to select speed; for measuring speed, it prompts to enter the full length value. In flash test mode, only speed selection is prompted.
Section 3: Cable Fault Testing Steps and Test Method Selection
Before testing cable faults, the tester must first determine the nature of the cable fault in order to adopt appropriate working and testing methods, in addition to mastering the performance and operation of this instrument.
First, use a megohmmeter or multimeter to measure the insulation resistance of each phase to ground and between phases at one end of the cable. Based on the resistance value, determine whether it is a low-resistance short circuit, an open circuit, or a high-resistance flashover fault.
When the resistance is below 200-300 ohms, it is a low-resistance fault; 0 to tens of ohms indicates a short circuit fault; extremely high to infinite resistance indicates an open circuit or broken wire fault. To confirm a broken wire, you can also short-circuit the far end of the cable and measure the resistance of the shorted two phases at the near end with a multimeter. Such faults can be directly measured using the low-voltage pulse method.
When the resistance is very high (hundreds of megohms to gigohms) and there is instantaneous discharge during high-voltage testing, such faults are generally called flashover faults and can be determined using the DC high-voltage flash testing method.
High-resistance faults: resistance higher than low-resistance faults, and determined by the DC high-voltage flash testing method during high-voltage testing.
After rough testing in a certain manner, proceed to pinpoint the fault location. If necessary, find the cable path and measure the cable length or distance.
Note: The above information and technical parameters are compiled and published by Yangzhou DARUI Electric Co., Ltd.
