1、 Overview
grounding fault locator is mainly used in the distribution network when single-phase grounding occurs. It has the characteristics of light structure, simple operation, accurate positioning and convenient measurement.
The instrument consists of signal source, detector, cable package, connecting rod, double spring hook and grounding pile.
2、 Reference standard
GB / T156 standard voltage;
GB / T191 packaging, storage and transportation graphic signs;
GB / t17626.2 electromagnetic compatibility test and measurement technology electrostatic discharge immunity test;
GB / t17626.3 electromagnetic compatibility test and measurement technology radio frequency electromagnetic field radiation immunity test;
GB / t17627.1 high voltage test techniques for low voltage electrical equipment Part 1: definitions and test requirements;
GB / t2423.1 environmental testing for electrical and electronic products Part 2: Test methods test a: low temperature;
GB / t2423.2 environmental testing for electrical and electronic products Part 2: Test methods test B: high temperature;
GB / t2423.5 environmental testing for electric and electronic products Part 2: Test methods Test Ea and guidelines: impact;
GB / t2423.8 environmental testing for electrical and electronic products Part 2: Test methods Test ED: free fall.
3、 Technical features
It is suitable for single-phase grounding fault detection of overhead grounding system;
It can accurately determine the position of single-phase grounding by adopting the principle of Measuring Grounding Fault fixed point by injecting signal current;
The ultra-low frequency signal can avoid the influence of distributed capacitance of the system, locate the high resistance fault, and detect the grounding impedance of 0-10k Ω;
The signal source adopts high-energy lithium battery, which can work continuously for no less than 10 hours;
The signal source can display output frequency, output current, output voltage and line grounding impedance at 22Hz frequency;
The detector uses the mirco USB interface for charging;
It is convenient to measure the load current of the power supply line by using the detector;
The detector adopts band-pass filter to filter the signal current, which ensures the measurement accuracy of signal current;
The detector adopts inverted U-shaped structure, which is convenient for hanging rod measurement;
The detector adopts wireless transmission communication to send the measurement results to the mobile phone, which is safe and reliable;
The system is compact and portable, and easy to carry.
4、 Technical parameters
4.1 Environmental parameters
Environment temperature: - 40 ℃ - + 70 ℃;
Relative humidity: 5-90% RH;
Altitude: < 3000m;
4.2 main technical parameters
Scope of application: overhead distribution network lines;
Line length: < 100km;
Fault location accuracy: < 0.5m;
Wireless communication distance: the wireless communication distance between the detector and the mobile app is not less than 15m;
4.2.1 working power supply:
Working power supply of signal source: 50wh polymer lithium mobile power supply;
Working power supply of detector: 3wh polymer lithium battery;
4.2.2 technical parameters of signal source:
Output characteristics of signal source:
Output voltage: ≤ 110V;
Output current: 10mA;
Output frequency: 22Hz;
Power supply mode of signal source: DC12V;
Power loss of signal source: ≤ 5W;
4.2.3 technical parameters of detector:
Measuring range of characteristic current: 0-15ma;
Load current measurement range: 0-600a.
5、 System principle
The fault location system includes signal source, signal source power supply, detector, APP software, cable reel, detector charging line, signal source power charger, insulation rod and grounding pile.
When there is a ground fault in the transmission line, the characteristic current is injected into the fault line by the signal source under the condition of determining the fault section and stopping the operation. According to Kirchhoff law, the characteristic AC signal forms a loop through the fault point, and the injection point of the characteristic current of the signal source is taken as the starting point, and the characteristics approximately equivalent to the injected signal can be measured from the beginning of the line to the fault point AC current, but not fault area (including non fault branch and fault point) can only measure weak induced current (caused by the influence of transformer and Pt on the line). Along the line, a detector is used to measure the characteristic AC signals flowing through each branch at the key branches, and the results are displayed on the mobile app. If the characteristic AC current can be detected in a branch, the fault point is downstream of the branch; if the characteristic AC current cannot be detected, the fault point is upstream of the branch. According to this principle, the grounding fault point can be accurately determined.