KYORITSU KEW 6010B User manual

KEW 6010B
MULTI-FUNCTION TESTER
INSTRUCTION MANUAL
KYORITSU ELECTRICAL INSTRUMENTS
WORKS，LTD.
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1．Safe Testing .................................................................................... 1
2．Instrument Layout ........................................................................... 3
3．Features ......................................................................................... 4
4．Specification ................................................................................... 6
5．Continuity (resistance) tests........................................................... 10
5．1 Test procedure ..................................................................... 10
6．Insulation Tests ............................................................................. 12
6．1 The nature of insulation resistance ....................................... 12
6．1．2 Capacitive current ............................................................... 12
6．1．3 Conduction current .............................................................. 13
6．1．4 Surface leakage current ....................................................... 13
6．1．5 Total leakage current ............................................................ 13
6．2 Damage to voltage sensitive equipment ............................... 14
6．3 Preparation for measurement ............................................... 15
6．4 Insulation resistance measurement ...................................... 15
7．Loop Impedance Tests .................................................................. 17
7．1 Voltage measurement ........................................................... 17
7．2 What is earth fault loop impedance?..................................... 17
7．3 Automatic over-temperature cut-out ..................................... 18
7．4 The loop impedance test ...................................................... 19
7．5 Loop impedance at 3 phase equipment................................ 20
8．RCD/Uc Tests ............................................................................... 21
8．1 Purpose of RCD Test ............................................................ 21
8．2 What does the RCD test really do?....................................... 21
8．3 What is Uc? .......................................................................... 22
8．4 Uc Testing ........................................................................... 23
8．5 Operation of KEW 6010B RCD testing ................................. 23
8．6 RCD testing ......................................................................... 23
8．6．1 "NO TRIP" and "TRIP" test ................................................... 23
8．6．2 "FAST TRIP" test .................................................................. 25
8．6．3 Testing DC sensitive RCDs................................................... 25
8．6．4 Testing Auto Ramp ............................................................... 25
8．7 Testing time delayed RCD's.................................................. 26
9．Store / Recall a measured result.................................................... 27
9．1 How to store the data ........................................................... 27
9．2 Recall the stored data .......................................................... 28
9．3 Delete the stored data .......................................................... 29
9．4 Transfer the stored data to PC.............................................. 30
10．Battery / Fuse replacement ........................................................... 31
11．General ........................................................................................ 32
12．Servicing ...................................................................................... 32
13．Case, Strap and Shoulder-pad assembly ...................................... 33
CONTENTS
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1. SAFE TESTING (READ BEFORE USING)
#
Electricity is dangerous and can cause injury and death. To avoid possible
electric shock, personal injury or damage of instrument, always treat it with
the greatest of respect and care. If you are not quite sure how to proceed,
stop and take advice from a qualified person.
1. This instrument must only be used by a competent and trained person and
operated in strict accordance with the instructions. KYORITSU will not
accept liability for any damage or injury caused by misuse or non-
compliance with the instructions or with the safety procedures.
2. It is essential to read and to understand the safety rules contained in the
instructions. They must always be observed when using the instrument.
3. This instrument is only intended for single phase operation at 230V AC
+10%, -15% phase to earth or phase to neutral operation, and then only for
Loop, RCD and Uc testing. For use in the continuity testing and insulation
testing modes this instrument must be used ONLY on circuits
which are de-energized.
4. Verify the tester's operation by measuring a known voltage before and
after using it.
5. When conducting tests do not touch any exposed metalwork associated
with the installation. Such metalwork may become live for the duration of
the test.
6. Never open the instrument case (except for fuse and battery
replacement and in this case disconnect all leads first) because dangerous
voltages are present. Only fully trained and competent electrical engineers
should open the case. If a fault develops, return the instrument to your
distributor for inspection and repair.
7. If the overheat symbol appears in the display " " disconnect the
instrument from the mains supply and allow to cool down.
8. For loop impedance tests to prevent unwanted tripping during loop testing
all residual current devices(RCDs) must be taken out of the circuit and
temporarily replaced with a suitably rated MCB unit. The RCD must be
replaced after the loop test is completed.
9. If abnormal conditions of any sort are noted (such as a faulty display,
unexpected readings, broken case, cracked test leads, etc) do not use the
tester and return it to your distributor for repair.
10. For safety reasons only use accessories (test leads, probes, fuses, cases,
etc) designed to be used with this instrument and recommended by
KYORITSU. The use of other accessories is prohibited as they are unlikely to
have the correct safety features.
11. When testing, always be sure to keep your fingers behind the safety
barriers on the test leads.
12.
During testing it is possible that there may be a momentary degradation of
the reading due to the presence of excessive transients or discharges on
the electrical system under test. Should this be observed, the test must be
repeated to obtain a correct reading. If in doubt, contact your distributor.
13.
The sliding shutter on the back of the instrument is a safety device. The
instrument should not be used if it is damaged or impaired in any way, but
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returned to your distributor for attention.
14.
Do not operate the function switch while the instrument is connected to a
circuit. If, for example, the instrument has just completed a continuity test
and an insulation test is to follow, disconnect the test leads from the circuit
before moving the function switch.
15. Do not rotate function switch when test button is depressed. If the function
switch is inadvertently moved to a new function when the test button is
depressed or in lock-down position the test in progress will be halted. To
reset, release test button and press again to restart testing on new function.
16. THE WIRING CHECK LED (P-E, P-N) of this instrument is to protect the user
from electrical shock resulting from incorrect connection of Line and Neutral
or Line and Earth.When the Neutral and Earth conductors are incorrectly
wired, the WIRING CHECK LED function cannot identify the incorrect
connection. Other procedures and test must be conducted to check and
confirm that the wiring is correct prior to making measurement. Do not use
this instrument to check the correct wiring of the power supply. Kyoritsu will
not be held liable for any accident that may result from incorrect wiring of
the power supply line.
17.
Use a damp cloth and detergent for cleaning the instrument. Do not use
abrasives or solvents.
Symbols used on the instrument
CAT. ⅢDesigned to protect against transient overvoltages in a building
wiring installation (low-voltage distribution level)

protected throughout by DOUBLE INSULATION or REINFORCED
INSULATION
This instrument satisfies the marking requirement defined in the
WEEE Directive. This symbol indicates separate collection for
electrical and electronic equipment.
Caution, risk of electric
shock #
Caution (refer to accompanying
instruction manual)
Protection against wrong
connection is up to 440V Earth Ground
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2. INSTRUMENT LAYOUT
TestLeadwithIECConnector
TestLeadforContinuityandInsulationTesting
LCDDISPLAY
Fig. １
IΔn SELECT SWITCH: Available FUNCTION NO.6, 7, 8, 9, 10
(MEMORY SELECT SWITCH)
0°/180°SELECT SWITCH: Available FUNCTION NO.4, 6, 7, 8, 9
(MEMORY RECALL SWITCH)
UL VALUE SELECT SWITCH: Available FUNCTION NO.6, 7, 8, 9
(ENTER SWITCH)
AUTO NULL SWITCH: Available FUNCTION NO.1
(MEMORY CLEAR SWITCH)
MEMORY MODE SWITCH
(MEMORY MODE EXIT SWITCH)
The switch name shown in ( ) is used in MEMORY MODE.
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KEW 6010B Multi-Function tester performs six functions in one instrument.
1. Continuity tester
2. Insulation resistance tester (500V/1000V)
3. Loop impedance tester
4. RCD tester
5. Uc tester
6. Mains voltage warning when operating the Loop, RCD and Uc mode.
Above test results: item1 through 5, can be saved to the internal memory; and
they can be recalled whenever necessary.
Data can be transferred from KEW6010B to PC by using MODEL8212 and
"KEW Report" (Optional accessory).
The tester is designed to Safety Standard
IEC 61010-1 CAT III (300V) Pollution degree 2, IEC 61557-1, 2, 3, 4, 6, 10.
Drip-proof construction in conformance with IP40, IEC 60529.
The instrument is supplied with:-
1. KAMP10 lead for Loop/RCD/Uc testing at socket outlets.
2. Model 7122B lead for Continuity and Insulation testing.
Continuity and insulation resistance functions have the following features:-
Rated current Continuity: 200mA as required in IEC 61557-4
(Buzzer sounds when test current exceeds 200mA)
Insulation: 1mA as required in IEC 61557-2
Live circuit warning A colour coded LED and buzzer warn if the
circuit under test is live.
Continuity Null Allows automatic subtraction of test lead
resistance from continuity measurements.
Auto discharge Electric charges stored in capacitive circuits
are discharged automatically after testing by
releasing the test button.
Loop impedance, RCD and Uc testing functions have the following features:-
Voltage level Supply voltage is displayed when the
instrument is connected to the supply until the
test button is pressed.
3. FEATURES
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Wiring check Three LEDs indicate if the wiring of the circuit
under test is correct.
Over temperature Detects overheating of the internal resistor
protection (used for Loop tests) and of the current control
MOS-FET (used for RCD and Uc tests) displaying
a warning symbol " " and automatically halting
further measurements.
15mA Loop Loop impedance 2000Ω range measurement
measurement is carried out with low test current (15mA).
The current will not cause tripping out involved
RCD even the one with the lowest nominal
differential current (30mA).
DC Test Allows testing of RCDs which are sensitive to
DC fault currents.
Phase angle selector The test can selected from either the positive
(0°) or from the negative (180°) half-cycle
of voltage.This will prevent tripping of some
polarized RCDs when Loop testing(20Ω range
only) and may give a more accurate reading
when testing RCDs.
UL(touch voltage limit) Select UL 25V or 50V with pressing the UL
value change and Uc value select switch. Where Uc value exceeds
monitoring UL, "UcH v" will be displayed without starting
the RCD test.
And at Uc range, can monitor the Uc value.
Other features:-
Auto data hold Holds the displayed reading until pressed
or rotated any switches after the test is
complete and at Loop/RCD/Uc range, until the
succeeding supply is applied.
Auto power off Automatically switches the instrument off after
a period of approximately 10 minutes. The
power-off state returns to normal when the
function switch is re-set to any position.
Data memory Can store 300 measured results.
Indication Flickers while the instrument is measuring.
Optional Accessory Model 7133B (OMA DIEC) distribution board
or lighting circuit test lead for LOOP/RCD/
Uc testing. Data can be transferred to PC via
Optical Adapter Model 8212 (with PC software
"KEW Report")
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4. SPECIFICATION
Continuity
Open Circuit
Voltage (DC)
Short Circuit
Current
Range Accuracy
Greater than 6 V
Greater than
200mA@2Ω
20/200Ω
Auto - Ranging
Up to 2Ω ± (3%rdg + 4dgt)
Over 2Ω ± (3%rdg + 3dgt)
Insulation Resistance
Function Open Circuit
Voltage (DC)
Rated Current Range Accuracy
500V 500V+20%-0%
1mA or greater
@ 500kΩ
20/200MΩ
Auto - Ranging ± (3%rdg + 3dgt)
1000V 1000V+20%-0%
1mA or greater
@ 1MΩ
Loop Impedance
Rated Voltage
(AC)
Nominal Test Current
at 0Ω External Loop Range Accuracy
230V+10%-15%
50Hz
25A/10ms 20Ω ± (3%rdg + 8dgt)
15mA/350ms max. 2000Ω
@ KAMP10 Test lead
RCD
Function
Rated
Voltage
(AC)
Test Current
Test
Current
Duration
Accuracy
Test Current Trip Time
x1/2
230V
+ 10%
- 15%
50Hz
10/30/100/300/500mA 2000ms -8% -2%
± (1%rdg
+3dgt)
x1 10/30/100/300/500mA 2000ms +2% +8%
FAST 150mA 50ms
DC 10/30/100/300mA
2000ms ±10%
500mA 200ms
Auto
Ramp
Goes up by 10% from 20%
to 110% of IΔn. 300ms x 10
±4%
Uc
Rated Voltage (AC) Test Current Range Accuracy
230V+10%-15% 50Hz
5mA at IΔn=10mA
100V +5% +15%rdg
±8dgt
15mA at IΔn=30/100mA
150mA at IΔn=300/500mA
Measurement Specification
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To prevent wrong connection of test leads and to maintain safety, the dedicated
terminals used for continuity and insulation tests are automatically covered
when using the terminals for Loop impedance, RCD and Uc tests.
Typical Number of Tests (central tendency for supply voltage up to 8V at R6P)
Continuity Ranges : Approx. 700 times min. at load 1Ω
Insulation Resistance Ranges : Approx. 1000 times min. at load 0.5MΩ(500V)
Approx. 800 times min. at load 1MΩ(1000V)
LOOP/RCD/Uc Ranges : Operational lifetime:5h (In case of continuous
duty)
Operating instrumetal uncertainty
● Operating instrumetal uncertainty of Continuity (IEC 61557-4)/Insulation Resistance (IEC 61557-2)
The influencing variations used for calculating the operating instrumetal uncertainty are denoted as follows;
Temperature : 0℃and 35℃
Supply voltage : 8V to 13.8V
● Operating instrumetal uncertainty of Loop Impedance (IEC 61557-3)
The influencing variations used for calculating the operating instrumetal uncertainty are denoted as follows:
Temperature : 0℃and 35℃
Phase angle : At a phase angle 0° to 18°
System frequency : 49.5Hz to 50.5Hz
System voltage : 230V+10%-15%
Supply voltage : 8V to 13.8V
Voltage Measurement
Rated Voltage (AC) Measuring Range (AC) Accuracy
100-250V 50Hz 100-300V 3% rdg
@ Loop/RCD/Uc Range
Function Range
20Ω
200Ω
500V
1000V
0.20-19.99Ω
20.0-199.9Ω
0.50 - 199.9MΩ
1.00 - 199.9MΩ
Measuring range to keep
operating uncertainty
Maximum percentage
operating uncertainty
±30%
Continuity
lnsulation
Resistance
Range
0.4-19.99Ω
100-1999Ω
Measuring range to keep
operating uncertainty
Maximum percentage
operating uncertainty
±30%
20Ω
2000Ω
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● Operating instrumetal uncertainty of RCD (IEC 61557-6)
The influencing variations used for calculating the operating error are denoted as follows:
Temperature : 0℃and 35℃
Earth electrode Resistance (shall not exceed below) :
System voltage : 230V+10%-15%
Supply voltage : 8V to 13.8V
Instrument dimensions:- 175 X 115 X 86mm
Instrument weight:- 840g including batteries.
Reference conditions Specifications are based on the following conditions
except where otherwise stated:-
1．Ambient temperature: 23± 5℃
2．Relative humidity 45% to 75%
3．Position: horizontal
4．AC power source 230V, 50Hz
5．DC power source: 12.0 V, ripple content 1% or
less
6. Altitude up to 2000m, Indoor use
Battery type Eight R6 or LR6 batteries.
Low battery warning "" symbol appears in the display if the battery
voltage drops below 8V.
Operating temperature 0 to +40℃, relative humidity 80% or less, no
and humidity. condensation.
Storage temperature -20 to +60℃, relative humidity 75% or less, no
and humidity condensation.
Surge protection transient overvoltage 4000V
Insulation resistance greater than 50MΩ at 1000V DC
(between enclosures and electrical circuits)
Function
-10% - 0%
0% -+10%
-10% -+10%
Operating uncertainty of trip current
×1/2
×1, FAST
Auto Ramp
Earth electrode resistance (Ωmax.)
IΔn (mA) UL50V
2000
600
200
130
80
10
30
100
300
500
2000
600
200
65
40
UL25V
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LED indication of live Illuminates if there is an alternating voltage of 20V
circuit warning AC or more in the circuit under test before Continuity
or Insulation resistance tests. When DC voltage is
detected across the measuring terminal the LED
lights up.
LED indication of The P-E and P-N LEDs illuminate when the wiring of
correct polarity the circuit under test is correct. The reverse LED
"" is lit when P and N are reversed.
Display The liquid crystal display has 3 1/2 digits with a
decimal point and units of measurement (Ω, MΩ, V,
mA and ms) relative to selected function.
Overload protection The continuity test circuit is protected by a 0.5 A 600
V fast acting (HRC) ceramic fuse mounted in the
battery compartment, where a spare fuse is also
stored.
The insulation resistance test circuit is protected by
a resistor against 1200 V AC for 10 seconds.
Mains Voltage On connecting test leads to the circuit under test at
Indication Loop, RCD and Uc ranges, the LCD reads VL-PE.
Indications are as follow:
Less than 100V : "Lo v"
100V~259V : voltage value and " "
260V~300V : voltage value and "Hi v"
alternately, and " "
Over than 300V : "Hi v" and " "
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5. CONTINUITY (RESISTANCE) TESTS
#WARNING
ENSURE THAT CIRCUITS TO BE TESTED ARE NOT LIVE.
DISCONNECT THE INSTRUMENT FROM THE CIRCUIT UNDER TEST
BEFORE OPERATING THE FUNCTION SWITCH.
TO SELECT THE LOW RESISTANCE RANGE SELECT "CONTINUITY"
5．1 Test Procedure
The object of continuity testing is to measure only the resistance of the parts of
the wiring system under test. Resistance value can be obtained by applying a
certain current to the resistor under test, and measuring the voltage generated
on the both sides of the resistor under test.
Resistance value(Ω) = Voltage(V) / Current(A)
This measurement should not include the resistance of any test leads used. The
resistance of the test leads needs to be subtracted from any continuity
measurement. KEW 6010B is provided with a continuity null feature which
allows automatic compensation for any test lead resistance.
Proceed as follows:-
1．Select the continuity test by rotating the function switch.
2．
Connect the ends of the test leads firmly together (see Fig 2) and press and
lock down the test button. The value of the lead resistance will be displayed.
3．Operate the AUTO NULL SWITCH, this will null out the lead resistance
and the indicated reading should go to zero.

Fig 2
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

Fig 3
4．Release the test button. Press the test button and ensure the display
reads zero before proceeding. While using the Continuity null function,
"" appears on the LCD. The null value will be stored even if power off
the instrument. The memorized null value can be cancelled by
disconnecting the test leads and pushing the AUTO NULL SWITCH with
the test button pressed or locked. CAUTION-before taking any
measurements always check the leads have been zeroed.
5．Connect the test leads to the circuit whose resistance is required (see Fig
3 for a typical connection arrangement). Having first made sure that the
circuit is not live. Note that the live circuit warning LED will illuminate
if the circuit is live - but check first anyway!
6．Press the test button and read the circuit resistance from the display. The
reading will have the test lead resistance already subtracted.
Note:
● If the circuit resistance is greater than 20Ω the instrument will autorange to
the 200Ω, and is greater than 200Ω the overrange symbol "OL" will remain
displayed.
#Warning:
Measurements may be adversely affected by impedances of connected
circuits in parallel or transient currents.
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#WARNING
ENSURE THAT CIRCUITS TO BE TESTED ARE NOT LIVE.
DISCONNECT THE INSTRUMENT FROM THE CIRCUIT UNDER TEST
BEFORE OPERATING THE FUNCTION SWITCH.
TO SELECT THE INSULATION RESISTANCE RANGE SELECT
“INSULATION”
6．1 The nature of insulation resistance
Live conductors are separated from each other and from earth metal by
insulation, which has a resistance which is high enough to ensure that the
current between conductors and to earth is kept at an acceptably low level.
Ideally insulation resistance is infinite and no current should be able to flow
through it. In practice, there will normally be a current between live conductors
and to earth, and this is known as leakage current. This current is made up of
three components, which are:-
1．capacitive current
2．conduction current, and
3．surface leakage current.
6．1．2 Capacitive Current
The insulation between conductors which have a potential difference between
them behaves as the dielectric of a capacitor, the conductors acting as the
capacitor plates. When a direct voltage is applied to the conductors, a charging
current will flow to the system which will die away to zero (usually in less than a
second) when the effective capacitor becomes charged. This charge must be
removed from the system at the end of the test, a function which is automatically
performed by KEW 6010B. If an alternating voltage is applied between the
conductors, the system continuously charges and discharges as the applied
voltage alternates, so that there is a continuous alternating leakage current
flowing to the system.
6. INSULATION TESTS
Fig 4
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6．1．3 Conduction Current
Since the insulation resistance is not infinite, a small leakage current flows
through the insulation between conductors. Since Ohm's Law applies, the
leakage current can be calculated from
Leakage current (μA) = applied voltage (V)
insulation resistance (MΩ)
Fig 5
6．1．4
Surface Leakage Current
Where insulation is removed, for the connection of conductors and so on,
current will flow across the surfaces of the insulation between the bare
conductors. The amount of leakage current depends on the condition of the
surfaces of the insulation between the conductors. If the surfaces are clean and
dry, the value of the leakage current will be very small. Where the surfaces are
wet and/or dirty, the surface leakage current may be significant. If it becomes
large enough, it may constitute a flashover between the conductors.
Whether this happens depends on the condition of the insulation surfaces and
on the applied voltage; this is why insulation tests are carried out at higher
voltages than those normally applying to the circuit concerned.
Fig 6
6．1．5
Total Leakage Current
The total leakage current is the sum of the capacitive, conduction and surface
leakage current described above. Each of the currents, and hence the total
leakage current, is affected by factors such as ambient temperature, conductor
temperature, humidity and the applied voltage.
If the circuit has alternating voltage applied, the capacitive current (6.1.2) will
always be present and can never be eliminated. This is why a direct voltage is
used for insulation resistance measurement, the leakage current in this case
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Insulation resistance (MΩ) = Test voltage (V)
Leakage current (ｵA)
As the capacitance of the system charges up, so the charging current falls to
zero and a steady insulation resistance reading indicates that the capacitance
of the system is fully charged. The system is charged to the full test voltage,
and will be dangerous if left with this charge. KEW 6010B provides an automatic
path for discharging current as soon as the test button is released to ensure that
the circuit under test is safely discharged.
If the wiring system is wet and/or dirty, the surface leakage component of the
leakage current will be high, resulting in low insulation resistance reading. In
the case of a very large electrical installation, all the individual circuit insulation
resistances are effectively in parallel and the overall resistance reading will be
low. The greater the number of circuits connected in parallel the lower will be
the overall insulation resistance.
6．2 Damage to Voltage-Sensitive Equipment
An increasing number of electronic-based items of equipment are being
connected to electrical installations. The solid state circuits in such equipment
are likely to be damaged by the application of the levels of voltage used to test
insulation resistance. To prevent such damage, it is important that voltage-
sensitive equipment is disconnected from the installation before the test is
carried out and reconnected again immediately afterwards. The devices which
may need to be disconnected before the test include:-
● Electronic fluorescent starter switches
● Passive infra-red detectors (PIRs)
● Dimmer switches
● Touch switches
● Delay timers
● Power controllers
● Emergency lighting units
● Electronic RCDs
● Computers and printers
● Electronic point-of-sale terminals (cash registers)
● Any other device which includes electronic components.
quickly falling to zero so that it has no effect on the measurement. A high
voltage is used because this will often break down poor insulation and cause
flashover due to surface leakage (see 6.1.4), thus showing up potential faults
which would not be present at lower levels. The insulation tester measures the
applied voltage level and the leakage current through the insulation. These
values are internally calculated to give the insulation resistance using the
expression:-
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6．3 Preparation for measurement
Before testing, always check the following:-
1. The low battery Indication " " is not displayed
2. There is no visually obvious damage to the tester or to the test leads.
3. Test the continuity of the test leads by switching to continuity test and
shorting out the lead ends. A high reading will indicate that there is a faulty
lead or that the fuse is blown.
4. MAKE SURE THAT THE CIRCUIT TO BE TESTED IS NOT LIVE. A
warning LED is lit if the instrument is connected to a live circuit but test the
circuit as well!
6．4 Insulation resistance measurement
KEW 6010B has a selectable, double test voltage of 500V and 1000V DC.
1. Select the insulation resistance setting by rotating the function switch to the
required test voltage - "500V" or "1000V" as indicated under the "insulation"
test section of the functional switch, after making sure that the instrument is
not connected to a live circuit.
2. Attach the test leads to the instrument and to the circuit or the appliance
under test. (see Figs 7 & 8)
Note : Insulation testing must only be undertaken on de-energised circuits.


Fig 7
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3．If the mains warning LED lights and/or the buzzer sounds DO NOT
PRESS THE TEST BUTTON but disconnect the instrument from the
circuit. Make the circuit dead before proceeding.
Fig 8
4. Press the test button when the display will show the insulation resistance
of the circuit or the appliance to which the instrument is connected.
5. Note that if the circuit resistance is greater than 20MΩ the instrument will
automatically range to the 200MΩ reading.
6. When testing is complete release the test button BEFORE disconnecting
the test leads from the circuit or from the appliance. This will ensure that
the charge built up by the circuit or the appliance during insulation test
is dissipated in the discharge circuit. In the discharging process, an LED
illuminates and the live circuit warning buzzer will sound.
#CAUTION
NEVER TURN THE FUNCTION DIAL WHILE THE TEST BUTTON IS
DEPRESSED AS THIS MAY DAMAGE THE INSTRUMENT. NEVER
TOUCH THE CIRCUIT, TEST LEAD TIPS OR THE APPLIANCE
UNDER TEST DURING INSULATION TESTING.
Note： If the reading measured greater than 200MΩ the over range reading
"OL" will be displayed.
At 1000V range, the buzzer sounds during testing (being pressed or
locked down the test button).


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7. LOOP IMPEDANCE TESTS
DISCONNECT THE INSTRUMENT FROM THE CIRCUIT UNDER TEST
BEFORE OPERATING THE FUNCTION SWITCH
TO SELECT THE LOOP TESTING RANGE SELECT“LOOP”
7.1 Voltage Measurement
Power on the instrument. When the tester is set to the Loop test function, mains
voltage is displayed as soon as the instrument is connected for test. This
voltage display is automatically updated every 1 second.
7.2
What is earth fault loop impedance?
The path followed by fault current as a result of a low impedance fault occurring
between the phase conductor and earth is called earth fault loop. Fault current
is driven round the loop by the supply voltage, the amount of current depending
on the voltage of the supply and on the impedance of the loop. The higher the
impedance, the lower will be the fault current and the longer it will take for the
circuit protection (fuse or circuit breaker) to operate and interrupt the fault.
To make sure that fuses will blow or that circuit breakers will operate quickly
enough in the event of a fault, the loop impedance must be low, the actual
maximum value depending on the characteristics of the fuse or the circuit
breaker concerned. Every circuit must be tested to make sure that the actual
loop impedance does not exceed that specified for the protective device
concerned.
For a TT system the earth fault loop impedance is the sum of the following
impedances (See Fig 9):
Fig 9
○ Even though the test current in the 2000 ohm range (15mA test current) is low
some RCD's may trip due to sensitivity or where there may already be
additional leakage in the circuit being tested.
○ The Loop impedance in a TN system is small and therefore it is not
recommended to test in the 2000 ohm range. RCD's will have to be bridged to
avoid tripping when using other test ranges.
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● Impedance of the power transformer secondary winding.
● Impedance of the phase conductor resistance from the power transformer to
the location of the fault.
● Impedance of the protective conductor from the fault location to the local
earth system.
● Resistance of the local earth system (R).
● Resistance of the power transformer earth system (Ro).
For TN systems the earth fault loop impedance is the sum of the following
impedances (See Fig 10):
Fig 10
● Impedance of the power transformer secondary winding.
● Impedance of the phase conductor from the power transformer to the location
of the fault.
● Impedance of the protective conductor from the fault location to the power
transformer.
7.3 Automatic over-temperature cut-out
During the short test period the instrument dissipates power of about 6 kW. If
frequent tests are conducted over a prolonged period of time, the internal test
resistor will overheat. When this happens, further tests are automatically
inhibited and the over-temperature symbol " " appears in the display. The
instrument must then be left to cool down, when testing may be resumed.
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