Beijing Tianli Relay Protection Automation Technology Co., Ltd.
(Beijing Tianli Automation Equipment Institute)

Add:16 Xueqing Rd., Haidian, Beijing, China
Tel:010-82755511 82755899


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Product name:TLZJ-2 Microcomputer-based DC System Ground Detection Device


    This device is applicable to on-line monitoring of 220V, 110V and 48V DC system insulation and selection of faulty ground lines, and can be widely used in DC systems of power plants and substations in such industries as electricity, petroleum, chemical industry, metallurgy, coal, railway and communication.

    Conventional DC system grounding detection device adopts low-frequency signal injection method which has two critical defects, first the detection accuracy is likely to be affected by the distributed capacitance of system; second, to inject an alternate current signal to DC system means introducing an interference source to the DC system that will affect its normal operation. Along with the development of sensor technology, DC micro-current sensor was invented which can be adopted to directly measure the leakage current of busbar and branch line, and calculate the insulation resistance according to leakage current. This method overcomes two critical defects of the low-frequency injection method.

Technical Index  

1  Section number of detected busbar: 1~2 sections.

2  Number of applicable detection loop

Main machine: 2 sections of busbar: 32 DC feeder loops;

Each expansion module: 16 DC feeder loops;

Expandable module: 16 pcs.

3  Input detection

3.1  Busbar voltage

Directly connect busbar voltage of DC system;

Voltage range and precision: 10~300 VDC, ±1%.

3.2  DC leakage current

It is introduced by the output end of DC leakage current sensor; the scope of input current is 0~ ±10 mA.

3.3  Precision of insulation measurement: (2K~500K) 5%.

3.4  Precision of branch line insulation measurement: (2K~500K) 10%.

4  Device power supply

AC 220V ± 20%, 50Hz;

DC 220V ± 20%;

Rated capacity of safety fuse, 1A.

5  Starting mode

The DC busbar insulation resistance to ground decreases to the set alarm limit.

6  Alarm output

There are 8 alarm relays for busbar overvoltage, busbar undervoltage, insulation resistance dropping and busbar ground.

The contact capacity of alarm relay: AC 220V, DC 24V and 5A. 

7  Power consumption

Power consumption of the entire machine: 30VA.

8  Communication interface

RS - 232C (three-wire)

RS - 485 (two-wire)

9  Environments

Ambient temperature: -5°C~+50°C;

Relative humidity (when the air temperature is + 20°C ) is not greater than 90%;

No violent shaking at installation site; there is no acidic, alkaline, corrosive and potential explosive gases in the air; indoor area where is free from rain, snow, wind and sand.

10  Transportation and storage conditions

1)  During the transportation process, products shall be free from vibration so as to protect the performance;

2)  The temperature range shall be -40 °C~+ 75°C, and the place shall be free from rain, snow, wind and sand intrusion.