M
MIT300 Series
Insulation and Continuity Testers
USER MANUAL
GSAFETY WARNINGS
■Safety Warnings and Precautions must be read and understood before the instrument is used. They must be observed during use.
■The circuit under test must be switched off, de-energised and isolated before test connections are made when carrying out insulation and continuity tests.
■Circuit connections and exposed metalwork of an installation or equipment under test must not be touched.
■The live circuit warning and automatic discharge are additional safety features which may fail and therefore safe working practices must be observed.
■The voltage function will only work if the instrument is functional and switched on.
■After insulation tests, capacitive circuits must be allowed to discharge before disconnecting test leads.
■The instrument should not be used if any part of it is damaged.
■Test leads, probes and crocodile clips must be in good order, clean and with no broken or cracked insulation.
■Ensure that hands remain behind guards of probes/clips when testing.
■National Safety Authorities may recommend the use of fused test leads when measuring voltage on high-energy systems.
■Replacement 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.
■The battery cover must be in place whilst conducting tests.
■The MIT310A is designed for use only in a controlled electromagnetic environment.
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.
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CONTENTS
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 (MΩ alarm ON/OFF (MIT320 only) |
13 |
MΩ threshold 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 |
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:
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.
N13117
Equipment complies with ‘C tick’ requirements
3
INTRODUCTION |
GENERAL DESCRIPTION |
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
The MIT300 series variants have the following features:
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MIT300 |
MIT310 |
MIT310A |
MIT320 |
MIT330 |
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Insulation testing |
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1 kV Insulation range |
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■ |
■ |
■ |
■ |
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500 V Insulation range |
■ |
■ |
■ |
■ |
■ |
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250 V Insulation range |
■ |
■ |
■ |
■ |
■ |
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Insulation test full scale |
999 MΩ |
999 MΩ |
999 MΩ |
999 MΩ |
999 MΩ |
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Insulation limit alarm |
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0.01 MΩ to 1 GΩ |
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■ |
■ |
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Continuity |
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Voltmeter range |
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(600 V digit) |
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■ |
■ |
■ |
■ |
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Continuity buzzer |
■ |
■ |
■ |
■ |
■ |
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Adjustable buzzer |
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threshold 1 Ω to 20 Ω |
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■ |
■ |
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Audible buzzer disable |
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■ |
■ |
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Lead null to 9.0 Ω |
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(0.5 Ω for MIT310A) |
■ |
■ |
0.5Ω |
■ |
■ |
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Stored test lead null |
■ |
■ |
■ |
■ |
■ |
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Resistance |
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10 Ω to 1M Ω resistance |
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range |
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■ |
■ |
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4
CASE CONTENTS
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MIT300 |
MIT310 |
MIT310A |
MIT320 |
MIT330 |
Features |
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Locking test button |
■ |
■ |
■ |
■ |
■ |
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Backlight and rotary |
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switch illuminations |
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■ |
■ |
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Voltage warning |
■ |
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Default voltmeter |
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■ |
■ |
■ |
■ |
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Auto-power-down with |
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defeat |
■ |
■ |
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■ |
■ |
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Switched test probe |
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connector |
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■ |
■ |
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Switched test probe |
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■ |
■ |
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Results storage |
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■ |
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Downloading |
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■ |
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USB |
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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 |
1 |
x |
Red/Black test lead set with clips |
8 |
x |
AA (LR6) batteries fitted |
1 |
x |
Warranty card |
1 |
x |
Certificate of test |
1 |
x |
Calibration certificate |
1 |
x |
CD containing user manual |
1 |
x |
Printed quick start guide |
1 |
x |
USB lead (MIT330 only) |
1 |
x |
SP4F switched probe (MIT320 and MIT330 only) |
5
LCD DISPLAY |
FRONT PANEL (DIGITAL INSTRUMENTS) |
|
MIT300, 310, 320 and 330 |
MIT310A
Test Lock LED
Moving coil
Analogue 
Test lead null display
indication
Battery check
Battery condition |
Voltage warning LED |
indication |
|
6
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
PREPARATIONS FOR USE (ALL INSTRUMENTS) |
GENERAL OPERATING INSTRUCTIONS |
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.
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.
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