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

INTRODUCTION

MEWOI3800N Accessories:

■ Detector

■ PCB Module

■ Connection Wire

■ Warranty card/Qualification card

■ Paper Box

SPECIFICATION

Technical Parameters

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).