Megger MIT515 Operating Manual
1
M
5 kV & 10 kV Insulation
Resistance Testers
USER MANUAL
2
G SAFETY WARNINGS
Safety warnings must be observed during use:
The 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
reenergised whilst the instrument is connected.
Only Megger supplied test leads must be used.
Circuit terminals must not be touched during an insulation
test or before suitable grounding of the unit under test is in
place in line with safe working practices.
After completing a test, capacitive circuits must be
completely discharged before disconnecting the test leads.
Capacitive charges can be lethal.
Tested items must 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.
The voltage indicator and automatic discharge features
must be regarded as additional safety features and not a
substitute for normal safe working practice.
It 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.
Test leads, including crocodile clips, must be in good
order, clean and with no broken or cracked insulation.
The instrument must not be used if any part of it is
damaged.
Insulation 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.
This instrument is not intrinsically safe and must not be
used in hazardous atmospheres.
If this equipment is used in a manner not specified by the
manufacturer, the protection provided by the equipment
may be impaired.
BATTERY WARNINGS
Do not disassemble or modify the battery. The battery
contains safety and protection devices which, if damaged,
may cause the battery to generate heat, rupture or ignite.
Never heat the battery in a fire or otherwise.
Do not pierce or damage the battery in any way
Do not subject the battery to strong impacts/shocks.
Do not expose the battery to water, salt water or allow the
battery to get wet.
Never short circuit, reverse polarity or disassemble the
battery pack.
In the event of a battery cell leaking, do not allow the liquid
to come into contact with the skin or eyes. If contact has
been made, wash the affected area with copious amounts
of water and seek medical advice.
Keep cells and batteries out of reach of children
Seek medical advice if a cell or battery has been
swallowed.
Do not leave a battery on prolonged charge when not in
use.
Retain the original product literature for future reference.
NOTE
THE INSTRUMENT MUST ONLY BE OPERATED 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.
3
Symbols used on the instrument
g
G Caution: refer to user manual
F Caution: risk of electric shock
Equipment protected throughout by Double Insulation.
Line Power / mains
c Equipment complies with current EU directives.
Equipment complies with current “C tick” requirements.
Do not dispose of in the normal waste stream.
g
Earth
CAT IV 600 V
Universal Serial Bus (USB)
Overvoltage category IV (equipment installed at or near
the origin of the electrical supply to a building)
600 V refers to the rms phase-to-earth voltage that this
instrument can withstand to the overvoltage category
IV rating.
4
Table of contents and index
General description.................................................................. 5
Features................................................................................... 5
Instrument Controls and Indicators.......................................... 6
Preparations for Use................................................................ 7
Initial instructions.................................................................. 7
Power lead and battery charging ......................................... 7
Functional verification ..........................................................7
Calibration ............................................................................ 7
Storage................................................................................. 7
Operating instructions............................................................. 8
General operation ................................................................ 8
Breakdown vs. burn mode ................................................... 9
Voltmeter .............................................................................. 9
Initial setup .....................................................................10
Lock Voltage................................................................... 10
Alarm setting................................................................... 10
Recording temperature................................................... 10
Breakdown mode / burn mode ....................................... 11
Running an insulation test .............................................. 11
Memory functions and downloading............................... 12
Real-time output during insulation tests ......................... 12
Battery indicator.............................................................. 13
On screen error reporting ............................................... 13
Measurement Modes ......................................................... 14
‘Spot’ IR test ................................................................... 14
Timed IR test .................................................................. 14
DAR and PI Insulation Tests .......................................... 14
Dielectric Discharge test................................................. 15
Step Voltage Test ........................................................... 16
Ramp voltage test........................................................... 17
Measurement Techniques.................................................. 18
Understanding Measurement Currents .......................... 18
Insulation measurements above 100 GΩ ....................... 18
Terminals........................................................................ 19
GUARD terminal, screened leads .................................. 19
Preventative measurement.................................................... 21
Cleaning ......................................................................... 21
Care of the instrument .................................................... 21
Leads ..............................................................................21
Battery Care.................................................................... 21
Replacing the battery...................................................... 21
Technical Specification .......................................................... 23
Electrical specification ........................................................ 23
Environmental Conditions .................................................. 24
GENERAL SPECIFICATION.............................................. 24
Repair and Warranty.............................................................. 24
Calibration, Service and Spare Parts ................................. 25
Returning product to Megger UK & USA service centres... 25
Approved Service Centres .................................................26
Accessories, Equipment and Spares..................................... 28
5
General description
The new range of Insulation Resistance Testers (IRT) are
smaller and lighter than previous models, yet offer advanced
features, improved battery life and rapid charge capability. The
range consists of three models; an entry level 5 kV and two
fully featured units, one 5 kV the other 10 kV. Resistance
measurement capability is up to 10 TΩ for the 5 kV models
and 20 TΩ for the 10 kV model.
A key productivity feature is the ability to operate with a
discharged battery when line/mains power is connected. An
intelligent battery charger ensures the optimum charge rate as
a function of battery level, resulting in extended battery life and
minimum charge times.
software, PowerDB, or to popular third party spreadsheet
packages.
The MIT515, MIT525 and MIT1025 can be powered from the
mains supply or by it’s rechargeable battery, which provides
for 4½ to 6 hours of continuous testing with a 100 MΩ load,
depending on model. A battery level indicator on the LCD
display indicates battery capacity. Connecting power to
line/mains supply will automatically charge the battery whether
the instrument is switched on or off, except during testing.
Features
10 TΩ max. resistance, 20 TΩ
for MIT1025
The tough case provides ultimate protection for a portable
instrument and a clip-on lead pouch ensures that supplied
leads remain with the instrument at all times. The case lid is
removable for improved lead access. IP rating is IP65 with
case closed ensuring no moisture ingress. High reliability is
built-in and all models are safety rated to CATIV 600 V.
Five preset voltage ranges are provided in insulation test
mode, plus a user settable lock voltage range which is useful
for repetitive measurements at specific test voltages. All test
voltages can be adjusted before and during the test using
up/down buttons. Preconfigured diagnostic tests like
Polarisation Index (PI), Dielectric Absorption Ratio (DAR),
Stepped Voltage (SV) and a ramp test are available along with
basic and timed insulation resistance tests.
Simplicity of operation is achieved with two rotary switches
whereby test voltage range and test mode are self evident.
The large backlight display enables multiple results to be
displayed, for example, the step voltage test shows five step
voltage resistance results simultaneously.
Advanced memory storage includes time/date stamping of
results, logging of data and recall of results to screen. A fully
isolated USB device interface is used for safe transfer of test
records to all versions of Megger’s data management
MIT515 with IR, IR(t), PI and
DAR
MIT525, MIT1025 diagnostic
and over voltage tests - PI,
DAR, DD, SV and ramp test.
Operate and charge on line
power/mains (except during
actual test)
Light weight Li ion battery
CATIV 600 V safety rating
Advanced memory with time/date stamp
DC and AC voltmeter (30 V to 660 V)
Large LCD display with backlight
Download of saved results and logs via 10 kV isolated
USB cable (MIT525, MIT1025 only)
PowerDB Lite software included with MIT525 and
MIT1025
6
Instrument Controls and Indicators
1. Positive (+) terminal
2. GUARD terminal
3. Negative (-) terminal
4. USB device interface
5. Four arrow buttons and OK button
6. TEST button with associated HV warning lamp
7. Backlight button
8. Central rotary switch
9. Save button on MIT525 and MIT1025
10. Test mode rotary switch
11. LED indicating line power / mains
12. Display
13. Power socket
User lock
voltage
Timer
Save
Open records
Battery
Ramp test
Danger HV
Fuse
Delete records
Download via
USB
Filter
Alarm
Breakdown
mode
Burn mode
Refer to manual
Noise detected
7
Preparations for Use
Initial instructions
Remove instrument, power lead and pouch from the
packing box.
Clip the test lead pouch to the lid.
Open the lid and familiarise yourself with the layout and
position of the IEC 60320 power inlet on the left side of
the panel. An isolated USB socket is found on the right
side of the instrument.
The battery must be charged between 0 ºC and 40 ºC
ambient temperature. If the battery detects a
temperature outside this range the battery symbol will
flash.
Power lead connection table
Connection UK/International USA
Earth/Ground Yellow/Green
Neutral Blue White
Live (Line) Brown Black
Green
Unpack leads and pack them into the lead pouch.
Read the product manual, especially the warnings.
A quick reference is provided in the instrument lid.
Keep the original packaging for re-use.
Power lead and battery charging
If the power lead supplied is not suitable for your
line/mains connection, do not use an adaptor. Always
use a power lead fitted with the correct plug. The
ground connection is not used as the instrument is
double insulated.
If using a fused plug, ensure that it is fitted with a 3 A
fuse.
Supply voltage: 90 to 265 V rms ac at 50/60 Hz.
A green LED illuminates when line power/mains is
present.
The battery will charge as long as the mains supply is
connected, except when a test is in progress.
For optimum battery life, charge the battery after each
use. Full charge duration is up to 2½ hours but a first
charge time of 3 hours is advised.
Functional verification
Simply turning on the instrument will initiate a start-up process
and the display will respond. If an error is detected ‘Err’ will be
displayed with an associated error number.
Calibration
The MIT515, MIT525 and MIT1025 are supplied with a
calibration certificate which is automatically generated as part
of Megger’s final test procedure.
UKAS accredited calibration certificates are available from
Megger but this service is chargeable.
Storage
Instruments should be stored in storerooms which meet the
storage temperature and humidity specifications listed in this
document. If charging is incorporated in the storeroom the
room must be well ventilated.
8
Operating Instructions
General operation
The MIT515, MIT525, MIT1025 Insulation resistance testers
(IRTs) are primarily controlled by two rotary switches and a
TEST button used to start and stop a test (see section entitled,
‘Instrument Control and Indicators’). The central rotary switch
includes an ‘OFF’ position; the instrument switches on by
rotating the switch either clockwise or anticlockwise from this
position. A range of test voltages for insulation resistance tests
up to 5 kV for MIT515/MIT525 and 10 kV for MIT1025 are
available, including a user selectable voltage range which can
be set between 100 V and 5000 V or 10000 V depending on
model. The ‘lockable’ test voltage range can be adjusted in the
settings function.
The settings function is indicated by a spanner symbol and
facilitates lock voltage, low resistance alarm, temperature,
time/date adjustment. A light blue coloured section of the
rotary switch denotes memory functions; open records,
download via USB and delete records. A dedicated save
button is provided on the MIT525 and MIT1025 models and all
models have a backlight button.
A second rotary switch controls the insulation test mode
providing for the following tests:
All models have basic insulation resistance IR, timed
insulation resistance IR(t), Dielectric Absorption Ratio
(DAR) and Polarisation Index (PI) tests.
MIT525 / MIT1025 have additional tests; Dielectric
Discharge (DD), Step Voltage (SV) and ramp test.
A cluster of directional buttons and an OK button are used in
settings and memory functions. The up/down arrows also
enable the test voltage to be adjusted during a test. Prior to
the start of an IR or IR(t) test, holding down the left arrow
button with a voltage level selected on the central rotary switch
will activate burn mode. Burn mode is deactivated if the
voltage range or mode is changed or by pressing the right
arrow/breakdown button.
Instrument controls are simple to operate. The central rotary
switch incorporates the OFF position. The left hand rotary
switch selects insulation test type (test mode switch). The
TEST button starts and stops a test.
Four arrow buttons and OK facilitate adjustment and selection
of settings, voltages and modes. Breakdown/burn modes are
set using the left and right arrow buttons. Backlight and save
functions are dedicated buttons. All models have backlight and
the MIT525 and MIT1025 have the Save button.
9
Breakdown vs. burn mode
In breakdown mode insulation tests are automatically stopped
when a fault causes the applied voltage to drop rapidly. Burn
mode IR tests ignore breakdown and continue to test the
insulation and are therefore destructive tests. Burn mode is
used to purposely create a carbon track in insulation to
facilitate fault location. Burn mode only operates at test
voltages of 500 V and above.
Voltage during discharge of a reactive load will be displayed in
addition to warning symbols. Non-reactive loads will discharge
too rapidly to show the voltage drop.
In the unlikely event of a fault during a test or during the
discharge process, the user is advised to check for flashing
high voltage warning symbols and the red LED on the
instrument panel will flash. If the warning symbols and LED do
not flash, turn off the instrument before disconnection.
Voltmeter
A voltmeter is incorporated in the
instrument and measures AC and DC
voltage from 30 V to 660 V. Frequency
(Hz) is measured and displayed for AC
voltages.
The voltmeter can be used to confirm
that the insulation is discharged and for
general purpose use. Positive and negative terminals are used
for the voltmeter function; do not connect the GUARD terminal
in voltmeter mode.
Before starting a test, the voltmeter detects any voltage
between the positive and negative terminals and will display
the voltage. If the voltage is above 50 V at the start of an
insulation test, a voltage is displayed on the analogue and
digital readouts to alert the user. The voltage displayed is
developed by current flowing through the internal discharge
resistance of the instrument. If the source impedance is high
the current will remain constant regardless of the value of the
internal discharge resistance.
In high electrical noise environments a lockout activates when
induced currents exceed the capability of the instrument to
remain within specified accuracies. The voltmeter reports the
voltage across the internal discharge resistor.
Reset Default Settings
Remove AC source, press OK, backlight buttons and switch
main rotary switch from OFF to setting icon.
Loading...