Megger S1-552/2 User manual

M
S1-552/2
5kV Digital Insulation Tester
USER MANUAL

GSAFETY WARNINGS
Safety Warning must be observed during use.
nThe circuit under test must be switched off, de-energised, isolated and checked to be safe before insulation test connections are made. Make sure
the circuit is not re-energised whilst the instrument is connected.
nCircuit connections must not be touched during an insulation test.
nAfter completing a test, capacitive circuits must be completely discharged before disconnecting the test leads. Capacitive charges can be lethal.
nTested items should be firmly shorted out with a shorting link, after discharge, until required for use. This is to guard against any stored dielectric
absorption charge subsequently being released thereby raising the voltage to potentially dangerous levels.
nThe voltage indicator and automatic discharge features should be regarded as additional safety features and not a substitute for normal safe working
practice.
nIt is rare, but in certain circumstances, breakdown of the circuit under test may cause the instrument to terminate the test in an uncontrolled manner,
possibly causing a loss of display while the circuit remains energised. In this event, the unit must be turned off and the circuit discharged manually.
nTest leads, including crocodile clips, must be in good order, clean and with no broken or cracked insulation.
nThe instrument should not be used if any part of it is damaged.
nInsulation testing in wet weather conditions might be hazardous. It is recommended that this instrument is not used in these circumstances. If this is
unavoidable, the user must take all necessary precautions.
nThis instrument is not intrinsically safe and must not be used in hazardous atmospheres.
2
NOTE
THE INSTRUMENT MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PERSONS.
Users of this equipment and/or their employers are reminded that National Health and Safety Legislation requires them to carry out valid risk
assessments of all electrical work so as to identify potential sources of electrical danger and risk of electrical injury such as inadvertent short circuits.
Where the assessments show that the risk is significant then the use of fused test leads may be appropriate.
CAT II
Measurement category II: Equipment
connected between the electrical outlets and
the user’s equipment.
CAT III
Measurement category III: Equipment
connected between the distribution panel
and the electrical outlets.
CAT IV
Measurement category IV: Equipment connected
between the origin of the low-voltage mains
supply and the distribution panel.

Test mode summary 16
Insulation resistance ‘IR’ test 16
Breakdown mode / burn mode 16
Alarm limit mode 16
Step voltage ‘SV’ test 17
Polarisation index ‘PI’ test, and dielectric absorption
ratio ‘DAR’ test 17
Dielectric discharge ‘DD’ test 17
Measurements above 100 GΩ18
Circuit block diagram 19
Specifications 20
Accessories 21
Repair and warranty 22
Battery replacement 22
Symbols used on the instrument are:
F Caution: risk of electric shock
G Caution: refer to accompanying notes
t Equipment protected throughout by Double
Insulation (Class II)
c Equipment complies with current EU directives.
This equipment should be recyled as electronic
waste.
Terms used in this manual
The word must is used to indicate that the instructions following should be
followed under all circumstances. Failure to follow these instructions could
result in damage to the instrument and / or a hazard to the operator.
The word should is used to indicate that the instructions indicate best practice.
CONTENTS
3
Safety warnings 2
Introduction 4
General description 4
Features 4
Cleaning 4
Power lead and battery charging 5
Instrument controls and indicators 6
Power On/Off button 7
Test voltage sand tbuttons 7
Test start / stop button 7
Ω/I button 7
Bbutton 10
Fn button 10
Mode button 10
Timer sand tbuttons 11
Record button 11
Recording to on-board memory 11
Downloading results 11
Deleting results 11
Recording to a PC 12
High voltage warning LED 12
Line input present LED 12
Test terminals 12
Guard terminal 12
RS232 / USB connections 13
Battery bar graph 13
Voltage at terminals 13
Timer indicator 13
Digital display 13
Analogue display 14
Secondary display 14
Pre-Test / during test key action table 14
Breakdown detection 15
Noise detection 15

Features
nContinuous resistance or current measurement on main display.
nOptional resistance, current, or figure of merit measurements on
secondary display.
nStandard test voltages – 250 V, 500 V, 1 kV, 2.5 kV, 5 kV
nNon-standard test voltages – selectable between 50 V and 1 kV in 10
V steps, and selectable between 1 kV and 5 kV in 25
V steps.
nTest modes include insulation resistance, polarisation index, step
voltage and dielectric discharge.
nThe dielectric absorption ratio is automatically calculated if the
corresponding timers are set.
nEither burn or breakdown selectable in insulation resistance mode.
nInsulation ‘Alarm Limit’ available in insulation resistance mode.
nProgrammable timers include a main test duration timer, plus T1 and
T2 timers for time resistance method type tests.
nLoad capacitance and time constant measurements – displayed at end
of test.
nLCD backlight.
nData storage, data retrieval and real time data output.
nUSB or RS232 communications.
nBattery level / charge level indicator.
INTRODUCTION
4
General Description
The S1-552/2 is a microprocessor controlled 5 kV insulation tester
offering measurement capability of up to 15 TΩ. The instrument
performs automatic tests and has data storage and data retrieval facilities.
Polarization index and dielectric discharge tests are performed
automatically, and test duration and voltages can be adjusted according
to user preference for these tests. A step voltage test can be performed
automatically, with a default voltage of 1 kV, and test duration of 5
minutes. It is possible for the user to set different voltages and test
durations for the step voltage test.
The S1-552/2 can be powered from the mains supply or by its own
internal rechargeable battery, which provides for at least 6 hours of
continuous testing with a 100 MΩload. A battery level indicator on
the LCD display indicates battery capacity. Connecting power to the
mains supply connector will automatically charge the battery whether
the instrument is switched ‘on’ or ‘off’, except during testing. A high
level of internal isolation allows the instrument to be used while the
unit is supplied from the mains. An internal battery management system
switches the instrument off after ten minutes of inactivity. If the battery
approaches a very low state of charge the instrument turns itself off, and
mains power must be applied before the instrument can be used again.
Recorded test results and settings will not be lost when the instrument is
switched off.
A comprehensive LCD display shows resistance, current, capacitance,
time constant, voltage, timer measurements, and figure of merit
measurements such as polarisation index.

POWER LEAD AND BATTERY CHARGING
5
Cleaning
Disconnect the instrument and wipe it with a clean cloth slightly
damped with soapy water or Isopropyl alcohol (IPA).
If the power lead supplied is not suitable for your mains connection,
do not use an adaptor. Always use a power lead fitted with the correct
plug.
The instrument is fitted with a two-pin IEC60320 power inlet. Most
power leads are made with three-core cable, so the ground connection
will not be used.
Power lead connection table
Connection UK/International USA
Earth/Ground Yellow/Green Green
Neutral Blue White
Live (Line) Brown Black
If using a fused plug, ensure that it is fitted with a 3 Amp fuse.
The instrument can be powered from 85 - 265 Vrms a.c. at 50/60 Hz.
The battery will charge as long as the mains supply is connected, except
when a test is in progress. The power On/Off button has a green LED,
which illuminates when mains power is present. For optimum battery
life, charge the battery after each use. A completely exhausted battery
will take 14 hours to recharge.

INSTRUMENT CONTROLS AND INDICATORS
6
Measurement terminals
-ve guard +ve
RS232
USB
Line
input
Time s and
t selectors
Voltage s
t selectors Line input
Present
indicator
Power on/off
Ω/I selector
Burn indicator Alarm Data recording
Test modes
Voltage at
terminals
Battery level
Breakdown
indicator
High voltage
warning
indicator
High
voltage
warning
indicator
Analogue
display
Timers
Main, T1,
T2
Dielectric
absorption
ratio/T1 timer
Digital
display
Polarisation
index/timer
T2
Time
constant
Capacitance
display
Data record
High voltage
warning indicator
Test start/stop
ModeFunction
Backlight
on/off

7
the test voltage is changed during a test, the new test voltage will be
displayed briefly.
When the test has stopped, the display continues to show the voltage
present on the test leads. Pressing either test voltage sor tbutton will
then display the test voltage immediately before the end of the test.
Test start / stop button
A test will only start if this button is pressed, held and then released as
soon as the red high voltage warning indicator LED lights. The LCD and
red LED high voltage warning indicators flash when the test starts.
A test will not start if the button is released before the red LED shows,
or pressed continuously for longer than 5 seconds. This is a safety
feature to prevent a test being started inadvertently.
The presence of a voltage greater than 50 V on the test leads is indicated
with flashing high voltage warning indicators. Testing is disabled if the
external voltage exceeds 50 V.
Testing will stop if the test start / stop button is pressed again, the
preset test time is reached, or, if the unit is not in burn mode, insulation
breakdown is detected.
When a test has finished, the instrument will discharge the load, which
may take some time. The operator must always check the load has been
discharged before touching the test leads.
Ω/I button
Pressing this button toggles the digital and secondary displays. The
details available when scrolling the secondary display will depend upon
the test mode selected, whether timers T1 and T2 have been set, and
Power On/Off button
The instrument will only turn on if this button is pressed, held and then
released when the display responds. The instrument will not turn on if
the button is released before the display responds, or if the button is
held down for too long. This is a safety feature to prevent the instrument
being inadvertently turned on.
The instrument is turned off either by pressing the button again, or if the
instrument is running on the battery, by timing out after 10 minutes of
inactivity.
Upon switching the instrument on the display will first show ‘Ini’ while it
undergoes a self-checking routine. When Ini disappears, the instrument is
ready for use.
Test voltage sand tbuttons
Using these buttons one of five test voltages can be selected: 250 V, 500
V,
1 kV, 2.5 kV, and 5 kV. The selected voltage is shown on the display.
A non standard voltage between 50 V and 5 kV can be selected by
holding down the ‘Fn’ function button whilst operating the buttons. The
selectable voltage is adjustable in 10 V steps between 50 V and 1 kV, and
adjustable in 25 V steps between 1 kV and 5 kV. An auto repeat facility
is enabled when the button is held down, allowing faster travel through
the range.
If there is an external voltage greater than 50 V on the test leads, the
high voltage warning indicators are flashed, and the display shows this
voltage instead. The instrument will not perform a test if this voltage is
greater than 50 V.
During a test the display shows the actual voltage on the test leads. If

8
Figure 1 - The result of an insulation resistance test (IR)
Test settings: T1 and T2 times set in order to measure the DAR
Test conditions: test runs for longer than 10 minutes as this is required
for a PI reading.
the duration of the test. The digital display toggles between insulation
resistance and current.
In the ‘IR’, ‘PI’, and ‘DD’ modes the secondary display initially shows the
PI (polarity index), DAR (dielectric absorption ratio), and, on completion
of the test, the TC (time constant) and capacitance measurements.
Toggling the display shows insulation resistances and currents.
In the ‘SV’ (step voltage) mode, the secondary display toggles between
insulation resistances and currents.
Figures 1 to 4 illustrate the display status for sequential ‘Ω/I’ key presses
in the different modes.
Press Ω/I
Press Ω/I
Press Ω/I

Figure 2 - The result of a polarity index test (PI)
Test settings: T1 and T2 times set in order to measure the DAR
Test conditions: timer defaults to 10 minutes, as this is required for a PI
reading
Figure 3 - The result of a dielectric discharge test (DD)
Test settings: T1 and T2 times set in order to measure the DAR
Test condition: test runs for longer than 10 minutes as this is required
for a PI reading.
Press Ω/I
Press Ω/I
Press Ω/I
9
Press Ω/I
Press Ω/I
Press Ω/I

10
Button Press Function Comment
Fn + VsIncrement in 10 V steps Voltage range between
50 and 1000 V
Fn + VtDecrement in 10 V steps Voltage range between
50 and 1000 V
Fn + VsIncrement in 25 V steps Voltage range between
1000 and 5000 V
Fn + VtDecrement in 25 V steps Voltage range between
1000 and 5000 V
Fn + Tsor TtCycle through timers Select main timer, T1
or T2
Fn + Mode Cycle through IR modes Select breakdown,
burn or alarm limit for IR
test
Fn + Download mode See ‘Downloading
results’
Fn + Clear stored data The ‘record’ button is
pressed twice
Mode button
Press down on the ‘MODE’ button to cycle through and select the test
mode. Modes of test to be chosen from include an insulation resistance
‘IR’ test, a polarization index ‘PI’ test, a step voltage ‘SV’ test, and a
dielectric discharge ‘DD’ test.
The insulation resistance ‘IR’ test operates in either ‘burn’ or ‘breakdown’
mode, with an option of setting a resistance threshold ‘alarm limit’. These
modes can be cycled through and selected by holding down the Fn
Bbutton
Pressing this button toggles the display backlight on and off.
Fn button
The function button when pressed allows other keys to perform another
function. This is summarized in the table below. ‘Vsand ‘Vtrepresent
the test voltage buttons. ‘Tsand ‘Ttrepresent the timer buttons.
Press Ω/I Press Ω/I
Figure 4 - The result of a step voltage (SV) test
Test condition: timer defaults to 5 minutes and test voltage defaults to
1000 V.