Megger MIT400/2 Series User manual

MIT400/2 Series
Insulation and continuity testers
User guide

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User guide contents
1. Introduction 3
2. GSafety Warnings 4
Symbols used on the instrument 4
WEEE Directive 5
Battery disposal 5
3. General description 6
Unpacking the carton 6
Carton contents (all instruments) 6
4. Preparations for use (all instruments) 7
Batteries 7
Preliminary test lead check 7
5. Instrument overview 8
General functions 8
Display contents 9
Terminal overview 10
6. General operating instructions 11
7. Input Terminals 12
2 terminal test lead connections 12
2 terminal + Guard (MIT2500) 12
3 terminal test lead connection 13
SP5 Switched probe (not MIT400/2) 15
8. AC/DC voltage and frequency
measurements 16
For 2 terminal instruments and MIT2500 16
For 3 terminal instruments
(MIT481/2, MIT485/2 only) 17
Result storage: 18
9. Insulation resistance testing 19
Measurement for 2 terminal instruments
and MIT2500 19
Variable voltage insulation testing
(MIT430/2, MIT485/2, MIT2500) 22
Polarisation Index (PI) and Dielectric
Absorption Ratio (DAR) 22
For 3 terminal instruments
(MIT481/2, MIT485/2 only) 25
ESD testing mode (MIT415/2 and
MIT400ESD) 26
REN mode 27
10. Continuity testing [Ω] 28
Measurement for 2 terminal instruments
and MIT2500 28
Single or bi-directional testing 29
Test lead null 29
Buzzer PASS/FAIL threshold 30
Buzzer ON/OFF 30
PASS / FAIL limit alarm 30
Test current - 20 mA / 200 mA 30
Measurement for 3 terminal instruments 30
Visual fast continuity (silent buzzer) mode 31
REL mode 31
11. Capacitance measurements 32
Capacitance measurement procedure
(2 terminals) 32
Distance measurement by capacitance 32
Capacitance measurement procedure
(3 terminals) 32
12. Saving, recalling and downloading
test results. 33
Saving test results 33
Test results recall 34
PI and DAR recall. 34
Deleting test results 35
Downloading test results 35
Procedure for pairing your MIT to the PC 35
Downloading data to the PC 36
13. SETUP Configuration options 38
14. Specification 39
15. Battery and fuse replacement 41
Battery condition and replacement 41
Procedure to replace batteries 41
Blown fuse indicator 42
Fuse replacement procedure 42
Preventive maintenance 42
16. Repair and Warranty 43
Calibration, Service and Spare Parts 43

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1. Introduction
Thank you for purchasing the Megger insulation test instrument.
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 MIT400/2 series of insulation and continuity test instruments.
These instruments are designed and manufactured by:
Megger Ltd
Archcliffe Road
Dover Kent CT17 9EN
England
Megger Limited reserves the right to change the specification of these instruments at any time without prior notice.

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2. Safety Warnings
2.1 Safety Warnings
Safety warnings and precautions must be read and understood before the instrument is used. They must be observed during use.
 National Health and Safety Legislation requires users of this equipment and their employers, 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.
 The voltage indicator and automatic discharge features must be regarded as additional safety features and not a
substitute for normal safe working practice which MUST be followed.
 The circuit under test must be switched off, de-energized, securely isolated and proved dead before test connections
are made when carrying out insulation and continuity tests.
 Test voltages greater than 1000 V dc must not be used on capacitive circuits. Capacitive charges can be lethal.
 Circuit connections and exposed-conductive-parts and other metalwork of an installation or equipment under test must
not be touched during testing.
 The Voltmeter function will operate only if the instrument is switched on and working correctly.
 After an insulation test, the instrument must be left connected until the circuit has been discharged to a safe voltage.
 Do not handle test leads above the 1000 V range. (For use in dry conditions only).
 The instrument should not be used if any part of it is damaged.
 All test leads, probes and crocodile clips must be in good order, clean and with no broken or cracked insulation. Verify
the integrity of the test leads before making measurements. Only “Megger” approved test leads must be used with this
product.
 Ensure that hands remain behind finger guards of probes/clips.
 National Safety Authorities may recommend the use of fused test leads when measuring voltage on high-energy
systems. Fused Leads must be tested independently before use to ensure fuse integrity.
 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.
 All covers must be in place whilst conducting tests.
 If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may
be impaired.
 The instrument must be used only by suitably trained and competent persons.
Grefer to user instructions
Frisk of electric shock
> 600 V
CATIV 600 V
g600 V ac rms maximum between
terminals, and between terminal
and earth
IP54 Enclosure is dust proof and
protected against water splashes
fFuse FF 500mA 1000V 30kA
t Equipment protected throughout
by Double Insulation.
Equipment complies with current
EU directives.
N13117 Equipment complies with
current “C tick” requirements.
Do not dispose of in the normal
waste stream.
Safety symbols marked on the instrument

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Installation Category Definitions:
CAT IV - Measurement category IV: Equipment connected between the origin of the low voltage mains supply and the distribution
panel.
CAT III - Measurement category III: Equipment connected between the distribution panel and the electrical outlets.
CAT II - Measurement category II: Equipment connected between the electrical outlets and the user’s equipment.
Measurement equipment may be safely connected to circuits at the marked rating or lower.
2.2 WEEE Directive
The crossed out wheeled bin symbol placed on Megger products is a reminder not to dispose of the product at the end
of its life with general waste.
Megger is registered in the UK as a Producer of Electrical and Electronic Equipment. The Registration No is WEE/
HE0146QT.
For further information about disposal of the product consult your local Megger company or distributor or visit your local
Megger website.
2.3 Battery disposal
The crossed out wheeled bin symbol placed on the batteries is a reminder not to dispose of them with general waste at the end of
their life.
This product contains the following batteries - AA alkaline batteries.
They are located under the battery cover at the rear of the instrument.
They can be safely removed by following the instructions in the battery replacement section of this guide.
Dispose of batteries according to local authority regulations.
Megger is registered in the UK as a producer of batteries.
The Registration number is BPRN00142.
For Further information see www.megger.com

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3.1 Unpacking the carton
There are important documents that you should read and keep for future reference.
3.2 Case contents (all instruments)
MIT400/2 MIT405/2 MIT410/2 MIT415/2 MIT417/2 MIT420/2 MIT430/2
MIT400/2 series instrument MIT400/2 MIT405/2 MIT410/2 MIT415/2 MIT417/2 MIT420/2 MIT430/2
Hard carry case 
Soft carry case
Red/black
test lead set with clips 
Red/Green/Black
test lead set
Red/Blue/Black
2.5 kV test lead set
AA (LR6) batteries fitted 6666666
Warranty card 
Calibration certificate 
Owners CD manual 
Quick start guide 
SP5 remote switched probe 
Download Manager software CD 
MIT481/2 MIT485/2 MIT2500
MIT480/2 series instrument MIT481/2 MIT485/2 MIT 2.5 kV series instrument MIT2500
Hard carry case   Hard carry case 
Soft carry case Soft carry case
Red/black
test lead set with clips
Red/black
test lead set with clips 
Red/Green/Black
test lead set   Red/Green/Black test lead set
Red/Blue/Black
2.5 kV test lead set
Red/Blue/Black
2.5 kV test lead set 
AA (LR6) batteries fitted 6 6 AA (LR6) batteries fitted 6
Warranty card   Warranty card 
Calibration certificate   Calibration certificate 
Owners CD manual   Owners CD manual 
Quick start guide   Quick start guide 
SP5 remote switched probe   SP5 remote switched probe
Download Manager software CD Download Manager software CD 
IMPORTANT -
To extend your warranty to 3 years, please register your Instrument at www.megger.com within one month of purchase.
3. General Description

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4. Preparations for use (all instruments)
4.1 Batteries
The Megger MIT400/2 series instruments are supplied with batteries fitted. When batteries become exhausted, refer to section 15 for
battery replacement.
Warning: Do not switch the instrument on or connect test leads with the battery cover removed.
4.2 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 W.
Note: Supply voltage
This instrument is designed for use on isolated (dead) circuits. Prior to any testing and using an approved method, ensure the circuit to
be tested has been fully disconnected and is securely isolated from the supply prior to using the instrument.

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5. Instrument overview
5.1 General functions
5.1.1 Rotary knob position:
Test functions are selected by turning the rotary knob from the OFF position to the desired function. The display will show the initial
screen for that function.
Press a black keypad button to change the test mode from the standard measurement, or to select the Backlight and Buzzer ON/OFF.
The rotary knob should always be returned to the OFF position after use. Do not rely on the AUTO OFF function as this unnecessarily
wastes battery life.
OFF Instrument OFF – no live circuit warning
VTrms Voltage AC/DC
500 V Insulation test range –
Press & hold button
500 V
LInsulation test range with gate*–
Press & hold Lto enable range
when selecting test function with rotary knob
(* where available)
WContinuity measurement from 0.01Wto
999 kW(automatic)
µF Capacitance measurement ( automatic)
L
Insulation test lock - Press and Lto
LOCK test ON
Start insulation test Press & HOLD to start
INSULATION test
W+ Nulls test lead resistance to 0.00W
when leads short circuit
Enter SETUP configurator (use and
Lto adjust settings)
5.1.2 Keypad button functions:
TRMS
Selects AC-Trms or DC mode
Insulation testing - Selects DAR, PI, Timed test
(t) or standard measurement (INS)
Insulation testing – Press during test for;
leakage (uA), test voltage (V) or timer (t))
Buzzer ON/OFF – not warning functions
Backlight ON/OFF
SETUP – Change setup value / After test –
SAVE result
SETUP – Select setup function
SETUP – Change function value
A+E+B
T+G+R Swaps measurement connection between
A-B, A-E & B-E (T-R, T-G & R-G)
Continuity testing – Press after “Continuity
measurement” to make “difference
measurement”
Insulation testing – Measures REN value
during insulation test
Capacitance testing – Measures REN value
during capacitance test
W

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5.2 Display contents
Symbol Description Symbol Description
GW, MW, kW, W, V, mV,
A, mA, Hz, nF, uF Units of measurement Measurement FAIL / PASS
Primary digital readout 3 Terminal selection status
Secondary digital readout REN measurement function enabled
Analogue readout with needle Transfer data to PC
Buzzer is enabled Save test measurement to memory
Lock enabled / disabled Test result recall to screen
FHazard voltage warning Delete test results
GWarning - Read user manual Bluetooth®enabled
zLead Null is enabled Battery condition
DW Difference between two ohms
measurements fFuse fail warning
G
Fz
f
k
M
G0
+35
100.01
8100.1
61004100
2100
-1510
9
8765
4
dB
+30
+20
+10
-10
0
W
W
W
8
A E B
T G R
mV
W
G mA
µ
W WD
Mk
FdB
µ
n
z
k
Am
µ
H
k V kft
M
W
kVs
Main digital
display
Secondary digital
display
Analogue arc and
pointer
Warning and
Advisory symbols
Storage and
downloading
symbols
A E B
T G R

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5.3 Terminal Overview
2 terminal connection 2 terminal connection 3 terminal connection
+ Guard

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6. General operating instructions
Safety note:
If 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 be prevented from performing an insulation test, protecting your instrument from
damage.
Note: This limit is increased on MIT481/2 and MIT485/2 to 75 V, but a warning buzzer will indicate voltages above
50 V.
Use extreme care when using or measuring voltages above 30 V, particularly in high energy systems.
Fused test leads are available as an optional accessory for local situations where increased protection is required.
Hazardous voltages can exist on the insulation test range all the time the [TEST]
button is locked down.

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7. Input terminals
Test leads connections are as indicated in below, which shows the test lead sockets at the top of the instrument, as well as the
switched probe socket and test lead.
7.1 2 terminal test lead connection
Terminal layout - 2 terminal instruments:
- Figure 1
2 terminal connection examples:
CAT III 600 V
G
g
- Figure 2
For two terminal instruments (Fig 1), the Red and Black test lead set should be connected to the appropriate sockets on the top of the
instrument marked + and –, respectively. (see figure 1 ).
The RED terminal accepts the standard RED test lead or the Switch Probe lead where supplied.
7.2 2-terminal + Guard (MIT2500)
The MIT2500 is fitted with a GUARD terminal. The GUARD terminal is used to conduct leakage currents away from the measured
circuit to reduce errors.
The GUARD terminal is ONLY used for insulation testing. Refer to Section 9
Terminal layout - 2 Terminal instrument + GUARD:
- Figure 3
For instruments with connection (figure 3) above, the Red / Black test lead set should be connected to the appropriate sockets on the
top of the instrument marked + and –, respectively. (see figure 3 ).

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2 terminal + Guard connection example:
CAT III 600 V
GG
g
- Figure 4
The GUARD lead (G) - refer to section 9 Insulation testing. is optional. When used it should be connected to the GUARD conductor,
screen, steel wire armoured conductor, or "user added" conductive wire or wrapper, such as foil. This "GUARD" conducts the
unwanted surface or "leakage current" away from the measured conductors.
7.3 3 terminal test lead connection
Three terminal connection provides measurement between the 3 pairs of a telecommunication cable (A-B, A-E & B-E) or between
single or three phase conductors (L-N, L-E, N-E) and (L1-L2, L1-L3 & L2-L3).
Alternatively, only a single pair can be used (default Red and Black) for conventional 2 wire measurement.
7.3.1 How 3 terminal connection works
The 3 terminal connections allow measurements to be made across any 3 terminals:
A-B, A-E or B-E (T-R, T-G, R-G)
This reduces the number of connections necessary to a circuit, especially where live working has been authorised. Once all three
leads are connected, measurements between the three terminals can be made.
For example:
Electrical testing:
 Where two conductors need to be measured to a screen or shield
 Where Live, Neutral and Earth need measuring
 Comparing continuity of conductors to a ground terminal for difference measurements
 Testing centre tapped electrical installations.
Telecommunications:
 Testing voltage, continuity and Insulation between A, B and E or Tip Ring and Ground, without having to disconnect
test leads.

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Terminal layout - 3 Terminal instrument:
- Figure 5
3 Terminal connection example:
CAT III 600 V
G
E
T
AR B
G
g
B / Ring / Live
E / Ground / Earth
A / Tip / Neutral
- Figure 6
7.3.2 3 terminal operation:
By pressing the A-E-B button on the keypad the active measuring pair on the Instrument changes as per the indication on the display,
as below:
- Figure 7
With each press, the display will change from:
From to to and back to
- Figure 8
Or, if 'T-G-R' is enabled in setup:
From to to and back to
For example, in VOLTS mode, the voltages on the A-B pair, the A-E pair or the B-E pair can all be measured without having to
disconnect the test leads from the A, B and E conductors.

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For electrical applications the test leads can be connected to Live (B), Neutral (A) and Earth (E) and the voltages measured and stored
without having to disconnect the test leads from the three conductors.
Test probes and crocodile clips are supplied for connection to the circuit under test.
Fused test leads are available as an optional accessory.
7.4 SP5 Switched probe (not MIT400/2, MIT405/2 )
The SP5 switch probe allows the user to start a test by pressing the test button on the probe, instead of on the instrument. This allows
for complete hands-free testing and increases user safety as below:
1. Connect the SP5 probe to the instrument using the special 3-pole +ve socket ( this replaces the RED test lead).
2. Select a suitable insulation resistance range.
3. Press and hold down the SP5 probe button. The instrument will start an insulation resistance test.
4. To end the test, release the probe test button.

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Note: Measured voltage must not exceed 1000 V phase to earth or Phase to Phase.
Exceeding this voltage could cause damage or electric shock hazard
Frequency measurement is not available on MIT400/2 and MIT405/2 model
Note on TRMS measurement: In TRMS mode the MIT will measure both AC and DC components of the supply voltage and display
the Trms value. In DC mode only the DC component is measured.
8.1 For 2 terminal instruments and MIT2500
8.1.1 AC Trms Voltage - Test procedure
1. Connect test leads to the RED and BLACK test sockets on the instrument.
2. Select the VOLTAGE measurement mode using the range knob [ V]
3. Connect the test leads to the circuit to be measured.
4. The instrument will display the voltage across the test leads, as below:
100 0
8 00
6 004 00
2 00
0
V
z H
- Figure 9
8.1.2 DC Voltage measurement
1. Repeat steps (1) to (4) above
2. Press the Trms AC/DC test button (below) to switch to DC measurement.
- Figure 10
The display will show a DC measurement as below:
100 0
8 00
6 004 00
2 00
0
V
- Figure 11
8. Voltage and frequency measurements V

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8.2 For 3 terminal instruments (MIT481/2, MIT485/2 only)
8.2.1 Using 2 test leads
1. Ensure instrument is in the A-B mode indicated in the display, as below:
- Figure 12
For details of changing the configuration see section 7.3 - 3 terminal connections.
2. Connect test leads to the RED/BLACK (B/A) test sockets only.
3. Select the VOLTAGE measurement mode on the range knob [ V] range).
4. Connect the test leads to the circuit to be measured.
5. The instrument will display the voltage across the test leads as below.
100 0
8 00
6 004 00
2 00
0
A B
V
z H
- Figure 13
Note: the display shows the A-B terminals are active.
6. If the display does not show the A-B option, press the A-E-B (T-G-R) button to change this mode, as below:
- Figure 14
7. With each press, the display will change from:
to to and back to
- Figure 15
Or, if 'T-G-R' is enabled in setup:

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to to
- Figure 16
8.2.2 Using 3 test leads
All three connections can be connected to the circuit under test, for example:
Electrical testing Telecommunications USA Telecommunications EU
A = Neutral T = Tip A = A
B = Live R = Ring B = B
E = Earth E = Earth E = E
The measurement should default to Live - Neutral (A-B) when the instrument is switched on.
Pressing the A-E-B (T-G-R) button will cycle through the voltages on each part of the circuit, see section 7.2.
8.3 Result storage
For MIT420/2, 430/2, 481/2, 485/2 and the MIT2500 the measured result may be stored (if required) by pressing the ‘STORE’
button for > 1sec. Refer to section 12 for further information.
WARNING - Where the A-E-B (T-G-R) symbol disappears, a voltage is present on a pair not currently selected, Press A-E-B
(T-G-R) to locate the live pair or pairs.

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9. Insulation resistance testing
Safety notes:
Danger of electric shock: Insulation resistance testing is performed at high DC voltages and is hazardous if touched. Always observe
the safety precautions when performing an insulation resistance test, and ensure all necessary health and safety precautions are
observed.
On the MIT2500 only use the 2.5 kV test lead set on test ranges above 1 kV.
Never hold test leads when using test ranges above 1 kV.
Circuit Isolation: The circuit under test must be completely de-energized and securely isolated before test connections are
made.
Automatic Discharge: Capacitive circuits are automatically discharged when the test button is released following an insulation test.
This is a safety feature to prevent hazardous voltages remaining on test circuits after testing is completed.
Live circuit detection:
Insulation tests must only be conducted on dead, isolated circuits. However, occasionally a live circuit may be connected by accident or
isolated circuits have a voltage present through coupling to an adjacent circuit.
If a voltage below 50 V appears on the circuit under test the instrument will complete a measurement.
On circuit voltages over 50 V the instrument will sound a warning buzzer and display the circuit voltage on test ranges that are not
designed to measure voltage, such as the insulation test. The instrument will be prevented from performing an insulation test. See
section 13 - SETUP
Note: The test disable limit is increased on MIT481/2 and MIT485/2 to 75 V, but a warning buzzer will indicate voltages
above 30 V.
Use extreme care when using or measuring voltages above 30 V, particularly in high energy systems.
Fused test leads are available as an optional accessory for local situations where increased protection is required. See section 13 -
SETUP
Hazardous voltages can exist on the insulation test range all the time the [TEST] button is locked down.
9.1 Measurement for 2 terminal instruments and MIT2500
Note: For all insulation tests up to 1000 V, the RED test lead can be replaced by the SP5 switched test probe.
The SP5 switch probe button operates the test functions in exactly the same way as the TEST button on the instrument, but without
having to look away from the equipment being tested.
9.1.1 Insulation testing
1. Connect test leads to the RED / BLACK test sockets on the instrument.
2. Select one of the test voltages on the insulation (MW) measurement mode using the range knob [ MW]. The Instrument will
display the range voltage selected in the display as below:
G0
0.01
0.1
110
100
W
8
W
M
V
G0
0.01
0.1
110
100
W
8
W
M
- Figure 17 MIT420/2 and MIT430/2 -Figure 17a MIT400/2 and MIT410/2
3. Connect the test leads to the circuit to be measured.

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4. Press the TEST button. The display will show the measured insulation value in both the analogue arc and large digital readout.
The test voltage at which the measurement was made is displayed on the small digital readout), as highlighted below:
G
G0
0.01
0.1
110
100
W
8
W
G
V
- Figure 18
5. Release the TEST button on completion of the test. The instrument will now discharge the circuit, ensuring it is left in a safe
condition at the end of the test.
WARNING: Locking on the insulation test, or disconnecting the leads before the test has completed can leave the circuit is a
dangerously charged condition, with risk of electric shock.
9.1.2 Buzzer PASS/FAIL threshold
The MIT will sound a buzzer if the measured value is greater than the threshold configured in SETUP. Refer to SETUP section 13.
9.1.3 Buzzer ON/OFF
The buzzer can be disabled by pressing the BUZZER button on the keypad as below:
- Figure 19
Note: Switching OFF the buzzer will disable the buzzer function but NOT the warning alarms.
9.1.4 Measurement PASS/FAIL
The display can show PASS or FAIL when the measurement is above or below the threshold in Setup when enabled. Refer to section
13 SETUP. This supersedes the test voltage display.
G
G0
0.01
0.1
110
100
W
8
W
G
- Figure 20