Megger MIT310 User manual

M
MIT300 Series
Insulation and Continuity Testers
USER MANUAL
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GSAFETY WARNINGS
nSafety Warnings and Precautions must be read and understood before the instrument is used. They must be observed during use.
nThe circuit under test must be switched off, de-energised and isolated before test connections are made when carrying out insulation and continuity
tests.
nCircuit connections and exposed metalwork of an installation or equipment under test must not be touched.
nThe live circuit warning and automatic discharge are additional safety features which may fail and therefore safe working practices must be
observed.
nThe voltage function will only work if the instrument is functional and switched on.
nAfter insulation tests, capacitive circuits must be allowed to discharge before disconnecting test leads.
nThe instrument should not be used if any part of it is damaged.
nTest leads, probes and crocodile clips must be in good order, clean and with no broken or cracked insulation.
nEnsure that hands remain behind guards of probes/clips when testing.
nNational Safety Authorities may recommend the use of fused test leads when measuring voltage on high-energy systems.
nReplacement fuses must be of the correct type and rating. Failure to fit the correctly rated fuse may result in a safety hazard and may cause damage to
the instrument in the event of an overload.
nThe battery cover must be in place whilst conducting tests.
nThe MIT310A is designed for use only in a controlled electromagnetic environment.
2
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.
NOTE
THE INSTRUMENT MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PERSONS.
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Insulation testing 15
Test lock 15
SP4F Switched (optional accessory for MIT320) 16
Test result storage (MIT330 only) 16
Replacing batteries and fuses 18
Low battery warning symbol 18
To replace batteries 18
Fuse replacement (user replaceable) 19
Preventive maintenance 19
Technical specification 20
Accessories and equipment 23
Repair and Warranty 24
Symbols used on the instrument are:
FCaution: risk of electric shock
GCaution: refer to accompanying notes
tEquipment protected throughout by Double
Insulation (Class II)
cEquipment complies with current EU directives.
Equipment complies with ‘C tick’ requirements
CONTENTS
3
Safety warnings 4
Introduction 2
General description 4
Case contents 5
LCD display 6
Front panel (digital instruments) 6
Connection panel 7
Lid open/closure 7
Preparations for use (all instruments) 8
Batteries 8
Preliminary test lead check 8
General operating instructions 8
General functions 8
Test lead connection. 9
Continuity measurement (MIT300, 310, 320, 330) 10
Test lead null 10
Continuity test (MIT300, 310,320, 330) 10
Continuity Buzzer (MIT300, 310, 320, 300) 11
Continuity buzzer mode: 11
Setup mode (MIT320/330 only) 11
Insulation testing - General 12
Insulation test 12
Test lock 13
Insulation test (MΩalarm ON/OFF (MIT320 only) 13
MΩthreshold adjustment (MIT320/330 only) 13
Insulation test lock disable (MIT320/330 only) 13
AC / DC Voltage measurement 14
Analogue Instrument MIT310A 14
Test lead null 14
Continuity test 15
Continuity buzzer test 15
N13117
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The MIT300 series variants have the following features:
MIT300 MIT310 MIT310A MIT320 MIT330
Insulation testing
1kV Insulation range nnnn
500 V Insulation range nnnnn
250 V Insulation range nnnnn
Insulation test full scale 999 MΩ999 MΩ999 MΩ999 MΩ999 MΩ
Insulation limit alarm
0.01 MΩto 1 GΩnn
Continuity
Voltmeter range
(600 V digit) nnnn
Continuity buzzer nnnnn
Adjustable buzzer
threshold 1 Ωto 20 Ωnn
Audible buzzer disable nn
Lead null to 9.0 Ω
(0.5 Ωfor MIT310A) n n 0.5Ωn n
Stored test lead null nnnnn
Resistance
10 Ωto 1M Ωresistance
range nn
INTRODUCTION GENERAL DESCRIPTION
4
Thank you for purchasing the Megger Insulation Tester.
For your own safety and to get the maximum benefit from your
instrument, please ensure that you read and understand the following
safety warnings and instructions before attempting to use the instruments.
This user guide describes the operation and functions of the following:
MIT300 Series of insulation and continuity testers:
MIT300
MIT310
MIT310A
MIT320
MIT330
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Please complete the warranty card and return it to Megger Limited as soon
as possible to help us reduce any delays in supporting you, should the
need arise.
Case contents
1 x MIT300 series insulation tester
1x Red/Black test lead set with clips
8xAA (LR6) batteries fitted
1x Warranty card
1 x Certificate of test
1x Calibration certificate
1 x CD containing user manual
1x Printed quick start guide
1 x USB lead (MIT330 only)
1 x SP4F switched probe (MIT320 and MIT330 only)
CASE CONTENTS
5
MIT300 MIT310 MIT310A MIT320 MIT330
Features
Locking test button nnnnn
Backlight and rotary
switch illuminations nn
Voltage warning n
Default voltmeter nnnn
Auto-power-down with
defeat nn nn
Switched test probe
connector n n
Switched test probe n n
Results storage n
Downloading n
USB n
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LCD DISPLAY FRONT PANEL (DIGITAL INSTRUMENTS)
MIT300, 310, 320 and 330
MIT310A
Voltage warning LED
Test Lock LED
Test lead null
Batterycheck
Battery condition
indication
Moving coil
Analogue
display
indication
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Memory control keys:
STORE: Store initiates the storing of a test result.
LAST/NEXT: Selects the type of location; ie Job, distribution
board, circuit, phase etc.
ESC: Aborts a save at any time.
OK: Final operation to save the result.
sSelects the job, db, circuit number; ie 01,02,03 etc
t
Lid open/closure
1. Open lid by lifting up front panel tab (1).
2. Fold-away underneath instrument (2 & 3) and push into retaining slot
(4).
Connection Panel
MIT300 Series test lead connections
An interlock sliding panel prevents connection of unsafe test lead
configurations. (MIT320/MIT330 only)
MIT330 Additional Controls
7
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GENERAL OPERATING INSTRUCTIONS
8
Safety note:
If a voltage greater than 25 V appears on the circuit under test the
instrument will default to a voltage measurement and display the
supply voltage.
On supply voltages over 50 V the instrument will prevent the test
button from performing an insulation test, protecting your
instrument from damage.
General functions
Voltage Testing on High Energy Systems
Use extreme care when using or measuring voltages above 30 V,
particularly in high energy systems. Fused test leads are available as
optional accessories for local situations where increased protection is
required. See accessories section.
Tests lock
The LOCK Lindicates when an INSULATION test range is locked ON.
It is activated by holding down the [TEST] button, and pressing the LOCK
Lbutton.
Note: See analogue section for MIT310A
Warning: Hazardous voltages can exist on the insulation test range all the
time the [TEST] button is locked down.
Voltage warning (MIT300 only)
If a voltage exists on the circuit under test, the instrument will emit a
warning beep.
If a voltage greater than 50 V exists, testing will be automatically inhibited.
Batteries
The Megger MIT300 series of instruments are supplied with batteries
fitted. When batteries become exhausted, refer to page 18, battery
replacement.
Warning: Do not switch the instrument on with the battery cover
removed.
Preliminary test lead check
Functional verification
1. Before each use of the instrument visually inspect the test leads, prods
and crocodile clips to confirm that their condition is good, with no
damaged or broken insulation.
2. Check continuity of the test leads by firmly shorting the leads together
and read the test lead resistance measurement directly from the display,
which should be less than 1.0 Ω.
Refer to page 10 for operation guide.
3. Supply voltage
Using an approved method, ensure the circuit to be tested has been
fully disconnected from the supply prior to using the instrument.
PREPARATIONS FOR USE (ALL INSTRUMENTS)
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Voltage warning (MIT310A only)
If a voltage exists on the circuit under test the voltmeter will indicate this.
However voltages under 50 V will be displayed but may be difficult to read
from the analogue display.
Default voltmeter (MIT310, MIT320 and MIT330)
The default voltmeter automatically operates if a voltage is present across
the test probes of greater than 25 V.
In Volts range the meter operates at greater than 2 V.
If the voltage exceeds 50 V any further testing is inhibited for safety.
The voltage will be displayed.
Backlight operation (MIT320 and MIT330 only)
Both the display and test ranges are backlit. The backlight function can be
selected at any time while the instrument is switched on by pressing the
BACKLIGHT Jbutton.
The backlight function will switch off automatically 20 seconds after the
instrument has finished testing.
Display warning symbols
GRefer to user manual
Any time the warning triangle is displayed the operator should refer to
the user manual for further information.
LRange lock
Displayed at any time the [TEST] button is locked in the on position.
zLead nulled
Indicates that the test lead resistance has been removed from the test
result.
Battery condition indication. Refer to page 18.
fFuse blown indicator, appears when an instrument fuse has failed.
Refer to page 19.
Test lead connection
The Red/Black test lead set should be connected to the appropriate
sockets on the rear of the instrument marked + and – respectively.
Test probes and crocodile clips are supplied for connection to the circuit
under test.
Fused test leads are available as an optional accessory, please refer to
accessories list at the end of this document.
Application
This instrument may be connected live to earth or between live
conductors of systems that have a rated voltage of 600 V a.c. rms to earth
and an installation (overvoltage) Category III or lower, or CATIV
applications with a rated voltage of 300 V or less.
This means that the instrument may be connected to any fixed wiring of a
building installation, but not to primary supply circuits such as overhead
cables. To maintain user safety and ensure accurate measurements, only
use the test leads supplied by Megger Limited.
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10
4. The display shows the resistance value. (Maximum 99,9 Ω)
5. Disconnect the test probes to terminate the test.
6. On completion of testing switch to the [OFF] position. Alternatively auto
shut off operates after a period of instrument inactivity.
All continuity measurements are AUTO ranging from 0.00 Ωto 100 Ωon
Digital/analogue scale).
The MIT310A has manual range selection to 2 kΩ.
From 0.00 Ωto 10 Ωtest current is greater than 200 mA. From 10 Ωto
100 Ωtest current is greater than 20 mA. (See page 15 for MIT310A)
Test lead Null
(See page 14 for MIT310A)
Before using the continuity range or buzzer range for the first time, the test
lead resistance should be ‘zeroed out’. This ensures any measurement does
not include the resistance of the test leads.
1. Connect the test leads to the instrument and firmly short both leads
together.
2. Wait for the reading to stabilise and press the [TEST] button.
3. Display of the zconfirms test leads zeroing. The display
should be 0.00 Ω.
Note: Lead zeroing is retained when the instrument is switched off, or auto
shut-off operates.
To remove the ‘lead zero’ press the [TEST] button again.
Continuity test (MIT300, 310,320 and 330)
(See page 15 for MIT310A)
Tomake a continuity measurement:
1. Turn the instrument ‘On’ by selecting the continuity Ωrange.
2. If required, zero test lead resistance, see test lead null (above).
3. Connect the test probes to the isolated circuit under test. The test will
start automatically.
CONTINUITY MEASUREMENT (MIT300, 310, 320, 330)
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