Kyoritsu Electrical Instruments Works, Ltd. 4118A User manual

MODEL 4118A
DIGITAL PSC-LOOP TESTER
INSTRUCTION MANUAL

CONTENTS
1. SAFE TESTING .................................................................................. 1
2. PROCEDURE OF REMOVING COVER ........................................... 4
3. FEATURES .......................................................................................... 5
3.1 Instrument Layout ........................................................................ 5
3.2 Test Lead ...................................................................................... 6
3.3 Features ........................................................................................ 7
4. SPECIFICATIONS .............................................................................. 9
5. OPERATING INSTRUCTIONS ......................................................... 10
5.1 Initial Checks ................................................................................ 10
5.2 Measurement of the Loop Impedance ...................................... 11
5.3 Measurement of Prospective Short Circuit Current .............. 12
6. DETAILED EXPLANATION ............................................................ 13
6.1 Measurement of Fault Loop Impedance and
Prospective Fault Current ........................................................ 13
6.2 Measurement of OLD-TT System .............................................. 18
6.3 Measurement of Line Impedance and
Prospective Short Circuit Current .......................................... 19
7. SERVICING ................................................................................... 20
8. CASE AND STRAP BELT ASSEMBLY .......................................... 20

— 1 —
1. SAFE TESTING #
This instrument has been designed and tested according to IEC
Publication 61010: Safety Requirements for Electronic Measuring
Apparatus. This instruction manual contains warnings and safety rules
which must be observed by the user to ensure safe operation of the
instrument and retain it in safe condition. Therefore, read through these
operating instructions before starting using the instrument.
#
WARNING
● Read through and understand instructions contained in this
manual before starting using the instrument.
● Save and keep the manual handy to enable quick reference
whenever necessary.
● The instrument is to be used only in its intended applications.
● Understand and follow all the safety instructions contained in
the manual.
Failure to follow the instructions may cause injury, instrument
damage and/or damage to equipment under test. Kyoritsu is by no
means liable for any damage resulting from the instrument in
contradiction to this cautionary note.
The symbol
#
indicated on the instrument means that the user must
refer to the related sections in the manual for safe operation of the
instrument. Be sure to carefully read instructions following each
symbol
#
in this manual.
#
DANGER is reserved for conditions and actions that are likely to
cause serious or fatal injury.
#
WARNING is reserved for conditions and actions that can cause
serious or fatal injury.
#
CAUTION is reserved for conditions and actions that can cause a
minor injury or instrument damage.

— 2 —
#
DANGER
● The instrument is to be used only in its intended applications or
conditions. Otherwise, safety functions equipped with the
instrument will not work, and instrument damage or serious personal
injury may occur. Verify proper operation on a known source before
use or taking action as a result of the indication of the instrument.
● This instrument is intended only for use in single phase operation at
230V +10% -15% AC phase to earth or for use in OLD-TT system
phase to neutral.
●
Do not exceed the maximum allowable input of any measurement range.
● Never attempt to use the instrument if its surface or your hand is wet.
● When conducting tests do not touch any exposed metalwork
associated with the installation. Such metalwork may become live
for the duration of the test.
● Keep your fingers and hands behind the protective fingerguard
during measurement.
● Be sure to remove the test lead from the mains power supply
promptly after measurement. Do not leave the instrument connected
to the mains power supply for a long time.
● Do not attempt to make measurement in the presence of
flammable gasses, fumes, vapor or dust. Otherwise, the use of
the instrument may cause sparking, which can lead to an
explosion.
● The instrument should be used only in its intended applications or
conditions. Otherwise, safety functions equipped with the
instrument do not work, and instrument damage or serious
personal injury may be caused.
#
WARNING
● Do not turn the function selector switch with plugged in test leads
connected to the circuit under test
● Do not install substitute parts or make any modification to the
instrument. Return the instrument to Kyoritsu or your distributor for
repair or re-calibration.
● If the overheat symbol appears in the display ( ) disconnect the
instrument from the mains supply and allow to cool down.
●
Never attempt to make any measurement, if the instrument has any
structural abnormality such as cracked case and exposed metal part.
● Stop using the test lead if the outer jacket is damaged and the
inner metal or color jacket is exposed.

— 3 —
#
CAUTION
● Do not expose the instrument to the direct sun, extreme
temperatures or dew fall.
● Always make sure to insert each plug of the test leads fully into
the appropriate terminal on the instrument.
● This instrument isn't dust & water proofed. Keep away from dust
and water.
● Use a damp cloth and detergent for cleaning the instrument. Do
not use abrasives or solvents.
●Measurement categories(Over-voltage categories)
To ensure safe operation of measuring instruments, IEC 61010 establishes
safety standards for various electrical environments, categorized as O to
CAT IV, and called measurement categories. Higher-numbered categories
correspond to electrical environments with greater momentary energy, so a
measuring instrument designed for CAT III environments can endure greater
momentary energy than one designed for CAT II.
O : Circuits which are not directly connected to the mains power supply.
CAT II : Electrical circuits of equipment connected to an AC electrical outlet
by a power cord.
CAT III : Primary electrical circuits of the equipment connected directly to the
distribution panel, and feeders from the distribution panel to outlets.
CAT IV : The circuit from the service drop to the service entrance, and to the
power meter and primary overcurrent protection device (distribution
panel).
O: Device which is
not directly
connected to the
mains power supply

— 4 —
2. PROCEDURE OF REMOVING COVER
Model 4118A have a dedicated cover to protect against an impact
from the outside and prevent the operation part, the LCD and the
connector socket from becoming dirty. The cover can be detached
and put on the back side of the main body during measurement.
Fig. 2
2.1 Method of removing the cover
2.2 Method of housing the cover
Fig. 1

— 5 —
3. FEATURES
3.1 Instrument Layout
1............ LCD display
2............ Wiring check LEDs
3............ Test button
4............ Range switch
5............ Connector
LCD Connector
Fig. 3
#
DANGER
● Use original test lead only.
● Max. allowed voltage between mains test terminals and ground is
300V.
● This instrument is intended only for use in single phase operation
at 230V +10% -15% AC phase to earth or for use in OLD-TT
system phase to neutral.
①②
③④
⑤
Wiring correct
（Green LED's）
Reversed L/N terminals
（Red LED）

— 6 —
3.2 Test Lead
The instrument is supplied with Model 7125 lead at socket outlets and Model
7121B distribution board lead.
(1) Model 7125
Mains lead mentioned in this instruction manual is Model 7125(EU)
European SCHUKO plug, however, there are some other types for the
areas, and the shipping is made along with the suitable plug-shaped
cable according to the areas of the globe as follows;
Model 7123 (AU) for Australian plug
Model 7124 (UK) for British plug (13A)
Model 7126 (SA) for South African plug
(2) Model 7121B
Black-Neutral
Protectivefigerguard
Red-Phase
Green-Earth
Protectivefigerguard
Protectivefigerguard
Fig.4
Protective figerguard:
It is a part providing protection against electrical shock and ensuring the
minimum required air and creepage distances.
The loop impedance of this instrument is adjusted to show the true value by
using the attached mains lead (either of Models 7123 through 7126) prior
to the shipment.
However, when the attached test lead for distribution board Model 7121B
is used, the total internal resistance shows approx. 0.1Ω bigger than those
of other mains lead due to the internal fuse resistance. Therefore, when
measurement is taken by using the Model 7121B, the measured value
between PHASE-EARTH shows approx. 0.1Ω bigger than the true value.
PHASE make sure that 0.1Ω subtracted from the measured value leaves
the true value in case of using the test lead of this distribution board.

— 7 —
As for the PSC range, use the following equation and divide supply voltage
by loop impedance, therefore, the measured value shows smaller than the
true value contrary to the case of the case of loop impedance range.
● PSC(A) = Supply Voltage(V) / Loop Impedance(Ω)
Choose and use the test leads and caps that are suitable for the
measurement category.
When the instrument and the test lead are combined and used together,
whichever lower category either of them belongs to will be applied.
Mechanical safety part:
Barrier: provides protection against electrical shock and ensuring the
minimum required air and creepage distances.
3.3 Features
3.3-1 Test Range (Function):
LOOP: 0-19.99Ω/0-199.9Ω/0-1999Ω
PSC: 0-199.9A/0-1999A/0-19.99kA
3.3-2 Applied Standards:
Instrument operation: IEC 61557-1, IEC61557-3
Safety: IEC 61010-1,2-030 CAT Ⅲ (300V) - instrument
IEC 61010-031 CAT Ⅲ (300V) - test lead
Protection degree: IEC60529 (IP 54)
EMC: IEC61326-1,-2-2
RoHS: EN50581

— 8 —
3.3-3 Other Features:
● Battery is not used All models are not battery-operated, but operate by
the voltage supplied from the system.
● Wiring check Three LEDs indicate if the wiring of the circuit
under test is correct. The P-E and P-N LEDs
illuminate when the wiring polarity of the circuit
under test is correct.
The Reverse LED is lit when P and N are
reversed.
● Over temperature
protection
Detects overheating of the internal resistor
displaying a warning symbol ( ) and automatically
halting further measurements.
● Overload protection Halts measurement to prevent damages to the body
when voltage between VL-PE is more than 260V.
"VL-PE Hi" is shown on the display.
● 15mA Loop
measurement
Loop impedance 2000 Ω range 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).
● Display The liquid crystal display has 3 1/2 digits with a
decimal point and units of measurement (Ω, A,
kA,V).
● Manual and Autotest mode
Manual －
Press and release the "Press to Test" button. The result will be
displayed for 3s and then the display will revert to AC voltage.
Autotest － The "Press to Test" button can be turned clockwise to lock it
down. In this auto mode, when using distribution board lead
M-7121B, tests are conducted by simply disconnecting and
reconnecting the red phase prod of the
M-7121B avoiding
the need to physically press the test button i.e. "hands
free".

— 9 —
4. SPECIFICATIONS
● Measurement Specification
Instrument dimensions 186×167×89mm
Instrument weight
750g
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． Altitude: Up to 2000m
Operating temperature 0 to +40℃ , relative humidity 85% or less, no
condensation.
Storage temperature － 20 to +60℃ , relative humidity 85% or less, no
condensation.
Symbols used on the

Equipment protected throughout by DOUBLE
INSULATION or REINFORCED INSULATION.
# Caution（refer to accompanying instruction
manual）
and humidity
and humidity
instrument
Loop Impedance
Prospective Short-circuit Current
Voltage
Range
20 Ω
200 Ω
2000 Ω
Measuring range
0.00 〜 19.99 Ω
0.0 〜 199.9 Ω
0 〜 1999 Ω
Nominal test c urrent
at 0 Ω external loop
25A / 20ms
2.3A / 40ms
15mA /280ms
Accuracy
± (2%rdg + 4dgt)
Range
200A
2000A
20kA
Measuring range
0.0 〜 199.9A
0 〜 1999A
0.00 〜 19.99kA
Nominal test c urrent
at 0 Ω external loop
2.3A / 40ms
25A / 20ms
25A / 20ms
Accuracy
Consider accuracy
of Loop Impedance
Measuring range
110 〜 260V
Accuracy
± (2%rdg + 4dgt)
Test current: a half-sine wave

— 10 —
5. OPERATING INSTRUCTIONS
5.1 Initial Checks - To be carried out
before any testing.
(1) Test Lead Connection
Insert the lead plug into the
connector on the instrument
correctly as shown below.
(2) Wiring Check
Before pressing the "Test Button" always check the LED's for the
following sequence:
P-E Green LED must be ON
P-N Green LED must be ON
Red LED must be OFF
#
CAUTION
● Always inspect your test instrument and lead accessories for
abnormality or damage. If abnormal conditions exist DO NOT
PROCEED WITH TESTING.
Lead Plug Fig. 5
● Operating Instrumental Uncertainty of Loop Impedance (61557-3)
Range
20 Ω
200 Ω
2000 Ω
Measuring range to keep
operating error
0.35 〜 19.99 Ω
20.0 〜 199.9 Ω
200 〜 1999 Ω
Maximum percentage operating
instrumental uncertainty
± 30%
The influencing variations used for calculating the operating
instrumental uncertainty are denoted as follows:
Temperature：0℃ and 40℃
Phase angle ：At a phase angle 0゜to 18゜
System frequency：49.5Hz to 50.5Hz
System voltage：230V+10%-15%
Harmonics : 5% of 3rd harmonic at 0°phase angle
6% of 5th harmonic at 180° phase angle
5% of 7th harmonic at 0° phase angle
D.C quantity : 0.5% of the nominal voltage

— 11 —
#
WARNING
● If the above sequence is NOT displayed or the RED LED is on for
any reason , DO NOT PROCEED AS THERE IS INCORRECT
WIRING. The cause of the fault must be investigated and rectified.
● 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.
(3) Voltage Measurement
When the instrument is first connected to the system, it will display the
phase-neutral voltage which is updated every 1s. This mode is cancelled
whenever the test button is pressed. If this voltage is not normal or as
expected, DO NOT PROCEED.
#
WARNING
● If the above sequence is NOT displayed or the RED LED is on for
any reason , DO NOT PROCEED AS THERE IS INCORRECT
WIRING. The cause of the fault must be investigated and rectified.
5.2 Measurement of the Loop Impedance
(1) Set the instrument to the 200Ω or 2000Ω range.
If the instrument is set to the 20Ω range slight sparking may occur
when testing with the distribution board lead although the unit has
been designed to minimize this.
(2) Connect the lead to the instrument.
(3) Plug the moulded mains plug to the socket being tested.
(4) Check the LED's are lit as indicated in section 5.1. If not DO NOT
PROCEED - check wiring.
(5) Note the mains voltage if required.

— 12 —
(6) Press the "Press to Test" button. The value of loop impedance will
be displayed with the appropriate units. A bleep will sound on
completion of the test.
For best results always test on the lowest possible range.
For example, a loop impedance measured on the 200Ω range may
give an indication of 0.3Ω whereas on the 20Ω range it may read
0.28Ω. In the event of the reading being in excess of the range (e.g.
more than 20 Ω on the 20Ω range) the appropriate over-range
symbol "OL" will appear on the display.
No harm will be done to the instrument by selecting too low a range.
#
CAUTION
● 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.
● Measured result may be influenced depending on the phase angle of
the distribution system when making measurement near a transformer
and the result may lower than the actual impedance value. Errors in
measured result are as follows.
System Phase
Difference
Error
(approx.)
10° -1.5%
20° -6%
30° -13%
5.3 Measurement of Prospective Short Circuit Current
(1) Set the instrument to the 20kA range.
(2) Connect the test lead to the instrument.
(3) Attach the plug to the socket to be tested.

— 13 —
(4) Check that the LED's are lit in the sequence indicated in section 5.1.
If not, disconnect from the mains and check the wiring at the socket.
(5) Press the "Press to Test" button. The prospective short circuit current
(PSC) will be directly displayed on the LCD with the appropriate units.
This will remain for 3s and then revert to AC voltage display.
An audible beep will sound on completion of the test. For best results
always test on the lowest possible range.
For example a PSC measured on the 2000A range may read 60A
whilst on the 200A range it may read 56.0A. To hold the reading keep
the button held down or turn clockwise to lock for Auto Test.
Normally PSC tests are conducted at point of origin, e.g. distribution boards,
between phase and neutral.
When conducting PSC tests at socket outlets, a test will be conducted
between phase and earth due to the fixed wiring of the moulded mains plug.
#
WARNING
● This instrument is intended only for use in single phase operation
at 230V +10% -15% AC phase to earth or for use in OLD-TT
system phase to neutral.
6. DETAILED EXPLANATION
6.1 Measurement of Fault Loop Impedance and Prospective Fault Current
If the electrical installations are protected by over-current protection
devices or by fuses, the Fault loop impedance should be measured.

— 14 —
In the event of a fault, the Fault loop impedance should be low enough
(and the Prospective Fault current higher enough) in order to have the
automatic disconnection of supply by the installed protection device within
prescribed time interval.
Every circuit must be tested to make sure that the fault loop impedance
does not exceed that specified for the over current protection device
concerned.
For TT system the Fault loop impedance is the sum of the following partial
impedances:
◦ Impedance of power transformer's secondary.
◦ Phase conductor resistance from power transformer to fault location.
◦ Protection conductor resistance from fault location to local earth
system.
◦ Resistance of local earth system R.
◦ Resistance of power transformer's earth system Ro.
The figure below shows in marked line the Fault loop impedance for TT
system.
Fig.6
For TN system the Fault loop impedance is the sum of the following
partial impedances:
◦ Impedance of power transformer's secondary
◦ Phase conductor resistance from power transformer to fault location
◦ Protection conductor resistance from fault location to power transformer

— 15 —
Fig.7
According to the international Standard IEC 60364 for TT system the
following condition shall be fulfilled for each circuit:
RA
＜
50/Ia
Where:
◦ RA is the sum of the resistances of the local earth system R and
protection conductor connecting it to the exposed conductive part.
◦ 50 is the max contact voltage limit (it could be 25V in particular cases)
◦ I a is the current causing the automatic disconnection of the protective
device within 5 s.
When the protection device is a residual current device (RCD), Ia is the rated
residual operating current I ⊿ n.
For instance in a TT system protected by a RCD the max RA values are:
Note:
● The loop tester models 4118A measure the fault loop impedance
that is a value normally a little bit higher of RA.
But, if the electrical installation is protected considering the loop
impedance value, also the RA formula will be fulfilled.
Rated residual operating current I ⊿ n.
RA (at 50V)
10
5000
2500
30
1667
833
100
500
250
300
167
83
500
100
50
1000
50
25
mA
Ω
Ω
RA (at 25V)
The figure below shows in marked line the Fault loop impedance for TN
system.

— 16 —
Practical example of verification of the protection in a TT system according
to the international Standard IEC 60364.
For this example max value is 1667Ω, the loop tester reads 12.74Ω, it
means that the condition RA
＜
50/Ia is respected.
It is fundamental for this example to test also the RCD to ensure that
operation takes place quickly enough to respect the safety requirements. In
order to do it, can be used the RCD tester model 5406A.
According to the international Standard IEC 60364 for TN system the
following condition shall be fulfilled for each circuit:
Zs
＜
Uo/Ia
Where:
◦ Zs is the Fault loop impedance.
◦ Uo is the nominal voltage between phase to earth.
◦ Ia is the current causing the automatic disconnection of the protective
device within the time stated in table as follows:
Note:
● For a distribution circuit a disconnection time not exceeding 5s is
permitted.
● When the protection device is a residual current device (RCD), Ia is
the rated residual operating current I ⊿n.
Uo (Volts)
120
230
400
>400
T (seconds)
0.8
0.4
0.2
0.1
Fig.8

— 17 —
For instance in a TN system with nominal mains voltage Uo = 230 V
protected by gG fuses the Ia and max Zs values could be:
Using the current ranges on models 4118A can be also tested the
Prospective Fault current.
Prospective Fault current measured by instruments must be higher than
Ia of the protective device concerned
Practical example of verification of the protection in a TN system according to
the international Standard IEC 60364.
Fig.9
Rating
(A)
Disconnecting time 5s
Ia (A) Zs ( Ω ) Ia (A) Zs ( Ω )
Disconnecting time 0.4s
6
10
16
20
25
32
40
50
63
80
100
28
46
65
85
110
150
190
250
320
425
580
8.2
5
3.6
2.7
2.1
1.53
1.21
0.92
0.71
0.54
0.39
47
82
110
147
183
275
320
470
550
840
1020
4.9
2.8
2.1
1.56
1.25
0.83
0.72
0.49
0.42
0.27
0.22

— 18 —
Max value of Zs for this example is 2.1Ω (16A gG fuse, 0.4s) the loop tester
reads 1.14 Ω (or 202 A on Fault current range) it means that the condition Zs
＜
Uo/Ia is respected.
In fact the Zs of 1.14Ω is less than 2.1Ω (or the Fault current of 202 A is
more than Ia of 110A).
6.2 Measurement of "OLD-TT System"
OLD-TT system is a TT system with phase to phase voltage of 220 V
(instead of 400 V) and phase to earth of 127 V (instead of 230V) and
normally the neutral conductor is not used.
Connecting the loop testers to this system, all three wiring check LEDs
should be lit and the display reads a value of 127 V.
Only if all these conditions are respected the test can be carry out.
Fig.10
#
WARNING
● This instrument is intended only for use in single phase operation
at 230V +10% -15% AC phase to earth or for use in OLD-TT
system phase to neutral.
● If the overheat symbol appears in the display ( ) disconnect the
instrument from the mains supply and allow to cool down.