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| Contact Us For Quotation | Email: 464560351@qq.com | Whatsapp&Wechat:+8618620373879 |
INTRODUCTION
MEWOI3800LC Earth Resistance On - line Detector is high-tech product that our company has devoted to "grounding resistance detection technology research" for more than ten years, specially design and manufacture for online monitoring grounding down lead connection status, circuit grounding resistance and metal circuit connection resistance. MEWOI3800LC is closed loop structure, convenient and efficient. On-line testing, non-contact measurement, grounding wire pass through the perforation of the detector, definitely not influence grounding for lightening effect and normal operation, real time on-line testing. Use by RS485 wire communication or GPRS wireless communication data transmission, realize remote online monitoring .Detector built-in sensor and circuit board, completely sealed, ensure high-accuracy, high stability and high reliability of long time on-line monitoring at field and indoors. MEWOI3800LC Earth Resistance On - line Detector suitable for transmission line tower grounding; Meteorological lightning protection grounding; Petrochemical grounding; Communication grounding; Substation grounding; Railway facilities grounding; Construction warehouse grounding; Metal circuit resistance; Electrical equipment grounding etc. MEWOI3800LC Earth Resistance On - line Detector could set up wired and wireless network system. Wired network system through RS485 communication protocol to transmit data, build up by the detector, 【communicator, monitoring software, power adapter, computer(above equipment need the user provide and secondary development) 】and other components; Suitable for short-distance ground resistance monitoring. Wireless network system through GPRS communication protocol to transmit data , build up by the detector(built-in GPRS transceiver module), 【SIM communication card, monitoring software, power adapter, computer(above equipment need the user provide and secondary development)】 and other components for long-distance ground resistance monitoring. Wired network system is suitable for monitoring within 1,500 meters distance, wireless network system is not subject to distance restrictions. |
MEWOI3800LC Accessories:
Detector
Fix Screw
RS485 Communication Wire
Warranty card/Qualification card
Paper Box
SPECIFICATION
Technical Parameter
| Function | Description |
| Function | Return circuit grounding resistance on-line monitoring, metal return circuit resistance connection online monitoring, grounding condition monitoring. |
| CT structure | Closed loop |
| Power Supply | Detector：6VDC～12VDC，50mA Max(GPRS 12VDC 150mA Max). (Ui：6V；Ii：50mA；Ci:0μF；Li:0mH；Pi：0.1W)（User supply)， Instrument and safety barrier matching relation：Uo≤Ui，Io≤Ii，Po≤Pi，Co≥Ci，Lo≥Li |
| Resistance Range | 0.01Ω~100Ω |
| Resolution | 0.001Ω |
| Accuracy | ±2%rdg±3dgt(20℃±5℃，below 70%RH) |
| CT Size | 56mm X 26mm |
| Overflow Indication | test data>100Ω, system software or LCD display “OLΩ” symbol; |
| Connection line | 1pcs ,1 meter cord(5 core wire) |
| Connection Identifier | Red/brown---power supply input anode; |
| Black--- power supply input cathode; | |
| Blue---RS485 signal anode; | |
| Grey---RS485 signal cathode; | |
| White--- grounding wire shield | |
| (power supply input cathode can connects with analog grounding by short circuit connection) | |
| Communication Method | Wired network: RS485 communication protocol(support MODBUS) |
| Wireless network: RS485 or GPRS communication protocol(support MODBUS) | |
| Network Points | Wired network: 1 ~ 250 grounding points, scalable |
| Wireless network: 60000 grounding points, can be expanded | |
| Communication distance | Wired network: about 1500m,scalable |
| Wireless network: not limited | |
| Alarm Indication | the detector sound-light alarm |
| Alarm Setting | System Software Settings |
| Data Display | None |
| Dimensions | Detector: 125mm × 119mm × 80mm |
| Weight | Detector: 1KG |
| Working Temperature And Humidity | -20℃~55℃ ; 20%RH~90%RH |
| Humidors Error | Within 5% |
| S hift | Automatic shift |
| Grounding Lead Interference Current | Should be avoid |
| External Magnetic Field | <40A/m |
| External Electric Field | <1V/m |
| Single Measurement time | About 0.5 second |
| Working current | Detector: 50mA Max.(GPRS: 12VDC 150mA Max) |
| Explosion-proof mark | Ex ia ⅡB T3 Ga |
| Explosion-proof Certification | CE18.2332X. |
| Protection Level | IP54 |
| Power Supply Mode | External power supply (Equipped by user) |
APPLICATION
Network Structure
Wired Network System (Self -Development Software)
Wired network system through RS485 communication protocol to transmit data, build up by the detector,【communicator, monitoring software, power adapter, computer (above equipment need the user provide and secondary development) 】and so on, suitable for short-distance 1500 meters grounding resistance monitoring.
Wireless Network System (Self -Development Software)
Wireless network system through GPRS communication protocol to transmit data ,build up by the detector(built-in GPRS transceiver module), 【SIM communication card, monitoring software, power adapter, computer(above equipment need the user provide and secondary development)】 and other components for long-distance ground resistance monitoring., distance is not limited.
Principle & Application
Test Principle
MEWOI3800 Earth Resistance On - line Detector, basic principle of measuring the grounding resistance is to measure the loop resistance. Firstly sensor send out a drive pulse signal to the measured ground return circuit, then measured ground return circuit responses a pulse electromotive force E, under the influence of electromotive force E will generate current I in the be measured ground return circuit. Sensor measures E and I value, and gets resistance value of be measured ground loop circuit through the formula: R=E/I.
Loop Resistance & Metal Loop Connection Resistance Tesing
Loop resistance is a composite value includes A point grounding resistance value, grounding down lead metallic conductor’s resistance value, metal overhead line’s resistance value, connection resistance value (contact resistance) between grounding down lead and metal overhead line, B point grounding resistance value.
If grounding network A and grounding network B up and down are connected together on the ground, Detector measures out the resistance value of metal return circuit is very small in general situation, only few of and less than one Ohm, this is the metal loop connection resistance, as a equipotential resistance, but not grounding resistance. Therefore the detector is much convenient to test metal return circuit connection resistance.
Test Method
Single point grounding system: If between grounding network A and grounding network B haven`t overhead line, and not connect together on the ground, then grounding network A and grounding network B can regard as standalone single point grounding connection. Detector cannot test the grounding resistance of single point grounding system directly, will display “OL” overload symbol. Therefore it needs adding one or more auxiliary grounding electrode, to form multipoint loop circuit.
Three point grounding system: In the following figure, the tested ground pole is A and the other two auxiliary ground pole is B and C. The poles A, B, C are connected together on the ground. In the three ground poles grounding down leads were installed on a detector, can accurately test the ground point A resistance value.
Calculated as follows:
R1=RA+RB//RC-------- (1)；
R2=RB+RA//RC-------- (2)；
R3=RC+RA//RB-------- (3).
SELECTION GUIDE
Digital Earth Resistance Clamp Meter
Click "blue"marked model No. for detailed Specificaiton
| Model | Range | Resolution | clamp size | RS232 | Data Storge | Other |
| 0.01Ω-200Ω | 0.001Ω | 65mm×32mm | optional | 99sets | |
| ø32mm | |||||
MEWOI3000B
| 55mm×32mm | |||||
MEWOI3000
| 0.01Ω-1000Ω | 0.001Ω | 55mm×32mm | 99sets | ||
| 0.01Ω-1200Ω | 0.001Ω | 65mm×32mm | optional | 99sets | |
| ø32mm | |||||
MEWOI3000D
| 0.01Ω-1000Ω 0.00-30.00A | 0.001Ω,0.05mA | 55mm×32mm | 99sets | ||
| 0.01Ω-1200Ω 0.00-20.00A | 0.001Ω,0.05mA | 65mm×32mm | optional | 99sets | |
| ø32mm | |||||
| 0.01Ω-1500Ω 0.00-40.00A | 0.001Ω,0.05mA | 65mm×32m m | √ | 99sets | Rechargable Batteries |
| 0.01Ω-100Ω | 0.01Ω | 60mm*30mm，(Closed) | Appoint with RS485 communication interface, provide standard MODBUS-RTU communication protocol | × | |
| 0.01Ω-100Ω | 0.01Ω | 60mm*30mm （Closed）， | × | LCD display,warning function. | |
| 0.01Ω-200Ω | 0.01Ω | Split Type 56mm×26mm | Wired network: RS232,RS485 standard communication protocol Wireless network: RS232、RS485、GSM communication protocol | × | |
| 0.01Ω-200Ω | 0.01Ω | Split Type 56mm×26mm | × | LCD display,warning function. | |
| 0.01Ω~2000Ω | 0.01Ω | 2/3-wires measurement, Online | |||
| 0.01Ω~2000Ω | 0.01Ω | 2/3-wires measurement, Online,GPRS | |||
| 0.01Ω～2000Ω; 0～600V | 0.01Ω,1V | √ | 400sets | 2/3-wires measurement of earth resistance/voltage | |
| 0.01Ω～2000Ω; 0～600V | 0.01Ω,1V | √ | 400sets | 2/3-wires measurement of earth resistance/voltage | |
| earth resistance:0.01Ω～30.00KΩ; soil resistivity:0.01Ωm～9000KΩm; 0～600V | 0.01Ω,0.01Ωm,1V | √ | 300sets | 2/3/4-wires measurement of earth resistance,soil resistivity,and earth voltage | |
MEWOI4200D
| earth resistance:0.01Ω～30.00KΩ; soil resistivity:0.01Ωm～9000KΩm; 0～600V | 0.01Ω,0.01Ωm,1V | √ | 300sets | 2/3/4-wires measurement of earth resistance,soil resistivity,and earth voltage | |
| earth resistance:0.01Ω～30.00KΩ;AC Leakage current: 0.00mA~600A; soil resistivity:0.01Ωm～9000KΩm;Earth Voltage:0.0~100.0V,dual clamp: 0.01Ω-100Ω | 0.01Ω,0.01Ωm,0.01A,0.1V | ø68mm | √ | 2000sets | 2/3/4-wires,selection & dual clamp method to measure the earth resistance,soil resistivity,earth voltage,AC voltage,AC leakage current,warning function. |
| earth resistance:0.01Ω～30.00KΩ;AC Leakage current: 0.00mA~600A; soil resistivity:0.01Ωm～9000KΩm;Earth Voltage:0.0~100.0V,dual clamp: 0.01Ω-100Ω | 0.01Ω,0.01Ωm,0.01A,0.1V | ø68mm | √ | 2000sets | 2/3/4-wires,selection & dual clamp method to measure the earth resistance,soil resistivity,earth voltage,AC voltage,AC leakage current,warning function. |
| Ground resistance:0.10Ω ～ 200Ω(4 clamp method) Ground resistance ( R ):0.10Ω ～ 20KΩ Soil resistivity ( ρ )0kΩm～9000kΩm AC current (A～)1mA～500.0A Ground voltage (V～)0.0V～200.0V | 0.01Ω,0.01Ωm,0.01mA,0.1V | ø68mm | √ | 100sets | Untie-free tower grounding resistance tester |
