Unit UT276A User manual

P/N:110401103514

Contents
UT276A/278A OPERATING MANUAL
I Safety Instructions
II Product Overview
III Unpack and Check
IV Product Specification
1 Series Types
2 Range and Accuracy
3 Technical Specification
V Clamp Meter Structure
VI Liquid Crystal Display
1 Liquid Crystal Display
2 Instruction for Special Symbol
3 Display Demonstration
VII Operation Methods
1 Power-on
2 Power-off
3 Resistance Measurement
4 Current measurement
5 Data hold/unlock/store
1
3
4
5
5
6
7
9
10
10
11
12
16
16
18
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1
I Safety Instructions
Thank you for purchasing the Clamp-on Ground Resistance of our company
and for the full use of the product, please:
Read the user manual carefully.
observe the operation notes listed in the manual.
Under no circumstances shall fail to pay attention to the safety in using the
clamp meter.
Pay attention to the stipulate measurement scope and operation environment.
The instrument shall apply to ground resistance testing instead of the current
of power frequency power wire, or it will affect the clamp's magnetic property
and the accuracy of ground resistance testing finally .
Pay attention to the labeled words on the surface board and backboard.
Before start it, pull the trigger once or twice to confirm the jaw of clamp can
close or open freely .
When starting it, don't pull the trigger and clamp any wires.
Clamp the objects being tested only after displaying the sign OL after
started the instrument.
UT276A/278A OPERATING MANUALUT276A/278A OPERATING MANUAL
7 Alarm Function Setting
8 Alarm Critical Value Inquiry
9 Data Wipe
10 Data Uploading to Computer
VIII Measurement Principles
1 Resistance Measurement Principle
2 Current Measurement Principle
IX Ground Resistance Measurement Method
1 Multi-point Ground System
2 Limited Point Ground System
3 Single Point Ground System
X On-site Application
1 Application of Power System
2 Application of Telecommunication System
3 Application of the building lightning protection ground system
4 Application of the gas station ground system
XI Notes about Ground Resistance Measurement
Appendix: loop Resistance Analysis
6 Data Inquiry 24
25
26
27
27
28
28
29
30
30
31
33
38
38
39
41
42
46
50

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Contact surface of the clamp jaw shall keep clean and refrained from cleaning
by corrosive and coarse matters.
Refrain from any shock on the clamp meter , especially the junction surface of
the clamp jaw.
It is strongly recommended using our company's explosion-proof Clamp-on
Ground Resistance tester in dangerous occasions.
The explosion-proof product is prohibited to dismantle and replace the battery
in dangerous place.
The clamp meter shall sound sporadically with light hum in measuring the
resistance, which is normal and shall be distinctive from the warning sound
beep--beep--beep-- .
Do not exceed the upper limits of the clamp meter in measuring the wire's
current.
Take out battery if do not use it for long time.
Dismantling, calibration and maintenance of the clamp meter shall be
conducted by the authorized qualified personnel.
If any danger might be resulted in continuation use by the inner reason of the
meter, stop using it immediately and pack it to the authorized qualified
institution to address the problem.
The contents labeled with * in the user manual shall be only applicable to
UT278A.
II Product Overview
The series of clamp-on ground resistance tester represents a significant
breakthrough of the traditional ground resistance measurement techniques and
apply widely to grounding resistance measurement in electricity,
telecommunication, meteorology, oilfield, architecture and industrial electric
equipment.
In measuring the ground system with loop, the series of clamp-on ground
resistance tester don't need to disconnect the ground down lead and any auxiliary
electrode, safe and fast, easy to use.
The series of clamp-on ground resistance tester can measure the grounding
problems with the traditional methods and apply to occasions traditional ways
can't measure as the tester measure the composite value of the grounding body
resistance and grounding down lead resistance.
UT276A 278A clamp-on ground resistance tester is the medium and high-end
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Product in the UT270 clamp-on ground series, its uniqueness are:
No long time waiting for start up, enter into testing immediately .
The only one clamp-on ground resistance meter with RS232 port, uploading the
stored data to PC.
A breakthrough of the relay self-checking method, adopt the advance arithmetic
and digital IC processing techniques.
Solving the bulkiness of old product, and meeting the portable meter property .
Add the sound-light alarm function with beep--beep--beep--
Add the recognition indication function of interference signal with beep--beep--
beep-- .
Measurement scope has increased to 0.01 -1200 .
With 99-group storage data, lower energy consumption, and with working current
less 50mA in maximum start up.
III Unpack and Check
Unpack and take out the instrument, please check carefully if the following
attachment are complete or intact, if any lack or damage were found, please
contact with your supplier .
Meter
Test ring
Data up-loading software disk
RS232 communication wire
R6 AA size dry batteries
Meter box
User manual, warranty , qualification certificate
1
2
1
1(1.8m)
4
1
A set
Types Measuring
resistance
Measuring
current Storing data RS232 port Warning
function
Yes No
Yes
Yes Yes Yes
Yes Yes Yes Yes
IV Product Specification
1 Series Types
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2 Range and Accuracy
Measurement mode Measurement Scope Resolution Accuracy
Resistance
*Current
3 Technical Specification
Resistance range
*Current range
Resistance resolution
*Current resolution
Data storage
RS232 port
Communication wire
Sound-light alarm
Scope of alarm critical value
setting
Power
Working temperature and
humidity
LCD
99groups
To upload stored data into the computer for
data analysis.
RS232communication wire with 1.8m long.
beep--beep--beep-- alarm press AL key to
control the on-off status.
Resistance 1-199 *current 1-499mA
6VDC (4 AA dry alkaline batteries )
-20 -55 10 RH-90 RH
4bit LCD digit display dimension
( 47mm 28.5mm)
UT276A/278A OPERATING MANUALUT276A/278A OPERATING MANUAL

50/60Hz (automatic)
Resistance measurement
frequency
Single measurement time
Outside magnetic field and
electric field
Full automatic shift
Structural characteristic Clamp CT
Double insulationProtection rate
Length, width and height 285mm 85mm
56mm
Clamp surface dimension
Clamp surface mass 1160g (inclusive of battery)
Clamp jaw stretch size
Clamp jaw dimension
89
65mm 32mm
28mm
Shift
40A/m 1V/m
0.5s
1KHz
*Frequency of the current
being measured
V Clamp Meter Structure
1 Long clamp head: 65 32mm
2 Trigger: control the closure and open
of clamp jaw
3 Function keys
ke key: (described as key POWER)
power on and off/exit
SAVE key: data inquiry/wipe data
AL alarm function key: alarm function
on/off
Left/right arrow key: resistance/current
mode conversion
4 HOLD key: hold/unhold display/store
5 LCD
6 RS232 port
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VI Liquid Crystal Display
1 Liquid Crystal Display
Alarm symbol
Battery low voltage symbol
Full stored data symbol
Data inquiry symbol
Number of 2-bit stored data group
Current, voltage unit symbol
Resistance unit symbol
Noise signal
Data hold symbol
Clamp jaw open symbol
DC symbol
Decimal point
4-bit LCD digital display
(14). AC symbol
2 Instruction for Special Symbol
(2)Er power-on error symbol. It might be caused by the dirtiness of the
clamp jaw, please clean the clamp jaw surface.
(4)OL symbol, it means the resistance being measured exceeds the upper
limit of the clamp meter.
(5)L0.01 symbol, it means the resistance being measured exceeds the
lower limit of the clamp meter.
(6)OL A symbol, it means the current being measured exceeds the upper
limit of the clamp meter.
indicates that it might be artificial pull-off the trigger; or the clamp jaw has
been too dirty to measure, requiring clamp jaw cleaning.
(1) clamp jaw open symbol. It shall display when the clamp jaw is open. It
the symbol would appear and replace battery in time or the measurement
accuracy couldn't be guaranteed.
(3) battery low voltage symbol. When the battery voltage is lower than 5.3V ,
it will flicker and the meter will sound sporadic beep--beep--beep-- .
(7) Alarm symbol, when the measured value exceed the alarm critical value,
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(8)MEM full stored data symbol, when the stored data has reached 99 groups
and can't store data anymore, the symbol MEM shall flicker.
Of stored data.
(9)MR Data inquiry symbol, it shall appear in inquiring data and indicate the No.
loop being measured, the symbol shall flicker and the meter sound sporadic
beep--beep--beep-- , the measurement accuracy of the time can't be
guaranteed.
(10)NOISE Symbol, when there are quite big interference current to the earth
3 Display Demonstration
(1)as clamp jaw is open, it can't measure.
(It might be caused by the dirtiness of
the clamp jaw, please clean the clamp
jaw surface.)
power-on error indication Er(Error)
(It might be caused by the dirtiness
of the clamp jaw , please clean the
clamp jaw surface.)
resistance of the loop being
measured <0.01
resistance of the loop being
measured is 5.1
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(5)resistance of the loop being
measured is 2.1,
hold the present measurement
value 2.1,
store automatically as the No.08
group data.
(6)inquiry the No.26group stored data
resistance of the loop being
measured is 0.028
(7)start alarm function and the current
being measured exceed the set
alarm critical value
battery low voltage display and the
measurement accuracy can't be
guaranteed.
current being measured is: 8.40A
hold the present display value
store the present hold value as the
No 37 group data.
(8)inquiry No 08 group stored data
resistance being measure is: 30.0
the data is measured under strong
interference signal
UT276A/278A OPERATING MANUALUT276A/278A OPERATING MANUAL