MEWOI3800N Built-in earth resistance online tester

OEM/ODM Testing Instruments Manufacturer

  • Main Features:: Circuit grounding resistance monitoring, metal loop resistance on-line monitoring, ground condition monitoring; ground wire, metal cable anti-theft monitoring.
  • Model No.:: MEWOI3800N
  • Name:: MEWOI3800N Built-in earth resistance online tester
Contact Us For QuotationEmail:  464560351@qq.comWhatsapp&Wechat:+8618620373879

MEWOI3800N Built-in Grounding Resistance Online Tester,Online earth resistance tester,GEO Meter


MEWOI3800N Non-contact Earth Resistance On-line Monitor is high-tech product that our company has devoted to "grounding resistance detection technology research" for more than ten years, specialize for online monitoring grounding down lead connection status, circuit grounding resistance and metal circuit connection resistance. On-line testing, non-contact measurement, grounding wire pass through the perforation of the detector, definitely will not influence grounding effective for lightening and normal operation, no need the self-inspection, real time on-line testing. Provide RS485 wire communication (support MODBUS-RTU communication protocol) , The monitor is composed of sensor and PCB module, which is suitable for user secondary development integration.

MEWOI3800N Non-contact Earth Resistance On-line Monitor 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 and others place. It can also be used for anti-theft monitoring of grounding wires and metal cables.

MEWOI3800N Non-contact Earth Resistance On-line Monitor can install and use singly, and also can set up wired or wireless network system.

MEWOI3800N Accessories:

■ Detector

■ PCB Module

■ Connection Wire

■ Warranty card/Qualification card

■ Paper Box


Technical Parameters

  FunctionLoop circuit grounding resistance on-line monitoring, metal return circuit resistance connection online monitoring, grounding condition monitoring. anti-theft monitoring of grounding wires and metal cables
Power SupplyDetector:6VDC~9VDC,50mA Max(external power supply).
Resistance  Range0.01Ω~100Ω
Accuracy±2%rdg±3dgt(20℃±5℃,below 70%RH)
PCB Size122mm×56mm×20mm
Sensor Size110mm×80mm×55mm
Sensor Perforation Size65mm×36mm
Sensor Weight595g;
Overflow IndicationTest data>100Ω, communication send “OLΩ” command
PCB InterfaceJ1:Signal output, power input interface     
J2:Sensor and PCB interface
Symbol J1P+:Power input with positive R+:Signal output with positive
P-:Power input ground   R-: Signal output with negative
GND:Signal ground, short connect with power input ground (P-)
Symbol J2I+、I-Current coil interface U+、U-Voltage coil interface
GND:Common ground
Connect Wire1pcs ,0.5 meter length(5 core wire)
  Line Wire1pcs ,1 meter length(5 core wire)
Connection IdentifierRed---power supply input anode;
Black--- power supply input cathode;
Green---RS485 signal anode;
Yellow---RS485 signal cathode;
White--- grounding wire shield
(power supply input cathode can connects with analog grounding by short circuit connection)
Communication methodRS485 communication protocol(support MODBUS)
GPRS communication (optional)
Working Temperature And Humidity-20℃~55℃; 20%RH~90%RH
ShiftAutomatic shift
Grounding lead Interference CurrentShould be avoid
External Magnetic Field<40A/m
External Electric Field<1V/m
Single Measurement timeAbout 0.5 second
Working current50mA Max.
InstallationThe ground wire goes through the center hole of the sensor
Installation DemandPCB should install into other protective case

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

MEWOI3800N Non-contact Earth Resistance On-line Monitor, the 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 return 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).


FunctionsCircuit grounding resistance monitoring, metal loop resistance on-line monitoring, ground condition monitoring; ground wire, metal cable anti-theft monitoring.
Output range0.00Ω~200Ω
Power Supply6VDC~9VDC,50mA Max.
Host Size110mm×80mm×55mm
PCB Size166mm×56mm×20mm
Ground perforation size66mm×36mm,Closed Type
Extend Wire1pc,1Meter(5Cores Wire)
Single Test TimeAbout 0.5Second
PCB InterfaceJ1,Signal output, power input interface
J2,The connection interface between the Host and PCB
J1 Identification

P+:Power Output+

P-:Power Input-

GND:Signal,Connect with Power Input(P-)

R+:Singal Output+

R-:Signal Input-

J2 Identification

I +, I-current coil interface

U +, U-voltage coil interface

GND: Common ground

Connection Line Identificatin

Red / brown --- Power input positive;

Black - Power input ground;

Blue --- RS485 signal is positive;

Gray --- RS485 signal is negative;

White --- shield to;

(Power input ground and shield can be short-circuit connection)

Communication Method

RS232, RS485 or MODBUS-RTU communication protocol

Overflow indication

When the display value is greater than 200Ω, the communication sends an "OLΩ" command

Working Temperature and Humidity-20℃~50℃; below 90%rh
Storage Temperature and Humidity-20℃~60℃; below 70%rh

Temperature and humidity error

Less than 5%
External magnetic field<40A/m
External electric field<1V/m
InstallThe ground wire passes through the center hole of the sensor
Installation RequirementsCircuit boards need to be placed in other protective box, to avoid rain, flooding installation
Power consumption50mA Max.
Power supply

External power supply

Ground interference current

Should be avoided


Automatic shift
AccessoriesSensor: 1 pc; PCB module: 1 pcs; Connection cable: 1 piece

Sensor: 1 pc; PCB module: 1 pcs; Connection cable: 1 piece

After Sales