MEWOI MEWOI3800P Bedienungsanleitung
Built-in Non-Contact Ground
Resistance Online Detector
MEWOI3800P
CONTENT
I. Brief Introduction ...........................................................................1
II. Technical Specifications................................................................2
III. Detector Structure and Dimensions .............................................4
IV. Usage method...............................................................................5
V. The Principle andApplication of Detection...................................6
VI. Basic Equipment........................................................................14
Attention Items:
Thank you for purchasing MEWOI3800P Built-in Non-Contact
Ground Resistance Online Detector of the company In order to
make better use of the product please be certain:
——To read this user manual carefully.
——To comply with the operating cautions presented in this
manual.
Apply to return circuit ground resistance, metallic return con-
nection resistance, grounding conditions, cable anti-theft
on-line monitoring.
Single point grounding system, needs to increase assistance
after the ends of the earth form a loop, then install detector.
Note that this detector specified measuring range and using the
environment.
Protection against rain shower and water logging of installation.
The detector and the circuit board can be built into other
equipment crate, which is convenient for integration.
Install waterproof and rainproof of device at outdoors.
The dismantling, calibration and maintenance the Detector shall
be operated by the authorized staff.
If the continuing use of it would be dangerous, the Detector
should be stopped using immediately, and immediately sealed
for the treatment by the authorized agencies.
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I. Brief Introduction
Built-in Non-Contact Grounding Resistance Online Detector is
our company devotes ourselves to Grounding resistance test tech-
nical research’s another new high-tech product for more than ten
years, built for online monitoring grounding down lead connection
status, return circuit grounding resistance and metal return circuit
connection resistance well-designed manufactured. on-line testing,
non-contact measurement, grounding wire pass through the hole,
real time on-line testing. Detector provides RS232 and RS485 signal
interface, provides standard MODBUS-RTU communication pro-
tocol. The detector and the circuit board can be built into other
equipment crate, which is convenient for secondary development
integration.
Non-Contact Grounding Resistance Online Detector is widely
applied in electric power, telecommunications, petrochemical, rail-
way, meteorology, military and other industries, building facilities,
electric power, electrical equipment, warehouse and oil depot of the
lightning protection grounding, protective grounding, or working
grounding, and also applied in anti-theft monitoring for ground wire
and metal cable.
Non-Contact Grounding Resistance Online Detector can be in-
dependent installation to use, and also can organizes a wire or wire-
less network system.
-2-
II. Technical Specifications
Function
Return circuit grounding resistance on-line
monitoring, metal return resistance connection
online monitoring, grounding condition moni-
toring, ground wire and metal cable anti-theft
monitoring.
Power Supply
Detector: DC6V~ DC9V, 50ma Max.
Resistance
Range
0.01Ω~ 200Ω
Resolution
0.001Ω
Indication
Range
0.00Ω~ 200Ω
Accuracy
±2 % rdg±3dgt(20°C ±5°C , below 70%RH)
Detector Di-
mensions
110mm×80mm×55mm
PCB Dimen-
sions
166mm×56mm×20mm
Grounding
Wire Perfora-
tion Size
60mm×30mm, closed mode
Overflow Indi-
cation
When show value is beyond 200Ω, detector
send out “OLΩ”
PCB Interface
J1: signal output, power supply input interface
J2: Detector and PCB interface
J1 Identifier
P+: power supply input anode;
P-: power supply input cathode;
GND: signal cathode, connects with power
supply input cathode by short circuit connec-
-3-
tion
R+: signal output anode
R-: signal output cathode
J2 Identifier
I+,I-: current coil interface
U+,U-: voltage coil interface
GND: common ground
Connecting
Line
A one meter long wire(5cores shielded wire)
Connection
Identifier
Red/brown---power supply input anode;
Black--- power supply input cathode;
Blue---RS485 signal anode;
Grey---RS485 signal cathode;
White--- analog grounding (power supply input
cathode can connects with analog grounding by
short circuit connection)
Protocol
Standard
RS232, RS485 or MODBUS-RTU communi-
cation protocol
Quality
Detector: 680g
Working Tem-
peratureAnd
Humidity
-20°C ~55°C ;20% RH~90% RH
Humiture Er-
ror
Within 5%
Shift
Automatic shift
GND Interfer-
ence Current
Prohibited
External Mag-
netic Field
< 40A/m
-4-
External Elec-
tric Field
< 1V/m
Single Meas-
urement Of
Time
About 0.5 second
Power Con-
sumption
50ma Max.
Installation
Grounding wire through Detector centre bore
Installation
Requirements
The circuit board need built into other equip-
ment crate, avoid rain and water logging
Power Supply
Mode
External power supply (Equipped by user)
III. Detector Structure and Dimensions
1. Grounding wire perforation size: 66mm×36mm.
2. Detector.
3. Signal output, power supply input thread
4. Signal output and power supply input connecting wire.
5. Detector and PCB connecting wire.
-5-
6. PCB.
IV. Usage method
1. Independent Installation and Use.
2. Set up Network Installation and Use
According to RS232, RS485 or MODBUS-RTU communication
protocol to set up a variety of networks to achieve remote monitor-
ing.
-6-
V. The Principle and Application of Detection
1. Testing Principle.
Built-in Non-Contact Grounding Resistance Online Detector’s
fundamental is measuring return circuit resistance. firstly Sensor
send out a drive pulse signal to be measured ground return circuit,
then measured ground return circuit responses a pulse electromotive
force E, under the influence of electromotive force E there will gen-
erate current I in the be measured ground return circuit. Sensor
measures E and I, and immediately gets resistance of be measured
ground return circuit through the formula: R=E/I.
2. Return Circuit Resistance Definition.
As picture: return circuit is a composite value includes A spot
grounding resistance, grounding down lead metallic conductor’s
resistance, metal overhead line’s resistance, connection re-
sistance(contact resistance)between grounding down lead and metal
overhead line, B spot grounding resistance. For the formative
above-mentioned return circuit’s grounding system, Detector can be
installed directly for monitoring, if the grounding system not form a
return circuit, it need adding auxiliary grounding electrode to form a
return circuit, further install the Detector, see the after-mentioned
single point grounding system. If the Detector measured out return
circuit’s composite value of grounding network A and grounding
network B is 5.0Ω, that is: RA+RB+RC+ RD=5.0Ω(RC and RD re-
spectively represent resistance of metal overhead line and grounding
down lead ), actual grounding resistance value of grounding network
A and grounding network B’s in parallel resistances less than or
equal to 2.5Ω, accordingly judge actual grounding resistance value
of grounding network A and grounding network B parallel connec-
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