Overview

The JDX and 1DX have the same appearance, features, functions, applications, and technical specifications. However, their internal structures and working principles differ. The 1DX contains only one core chip that can only detect short circuits. The JDX, on the other hand, contains a combined intelligent detection chip that detects both short circuits and ground faults. However, the accuracy of the passive fault indicator in detecting ground faults is relatively low. When connected to an asymmetrical current source (signal source), the accuracy of ground fault detection can reach over 95%.

Performance characteristics

◆ Fault indication: During normal operation, the window displays in white; when a short circuit or ground fault occurs, the window displays in red.

◆Online operation: Installed directly on the line, maintenance-free.

◆Strong anti-interference: The signal is not affected by lines, inrush current, high-order harmonics, current fluctuations, cable distributed capacitance bypass.

◆Automatic Reset: After the operation is completed, the device will automatically reset after a set time.

◆Live loading and unloading: Live loading and unloading is very simple and does not affect the operation of the line.

Working principle

The short-circuit fault principle in the combined grounding and short-circuit principle is the same as that in the 1DX.

Grounding detection principle: The first half-wave of the capacitive current and the first half-wave of the voltage at the instant of grounding are sampled and compared in phase. If the sampled capacitive current changes abruptly and exceeds a certain value, and is in phase with the first half-wave of the voltage at the instant of grounding, while the conductor-to-ground voltage decreases, then a grounding fault is determined to have occurred on the line. The fault indication diagram used to determine grounding shows that indicators 3, 6, and 9 of phase C on line #2 turn red while indicator 12 remains white, indicating a fault at the output point.

Application Scope

◆ Installed in the middle section and at the branch entrance of long lines, it can indicate the faulty section and faulty branch of the line.

◆ Installed at the transformer outlet, it can determine whether the fault is caused by the user.

◆ Installed at the user's transformer inlet, it can determine whether the fault is caused by the user.

◆ Installed at the connection between the cable and the overhead line, it can distinguish whether the fault is in the cable section. 

Installation tools

Figure A shows the installation tools for 1DX, JDX, and JDG. The specific installation method is simple: place an insulating rod at the bottom of the installation tool, unscrew the top bolt of the indicator, insert it into the installation tool, and then snap the indicator into the cable. Figure B shows the installation tools for JDX-Y.