Unpacking the carton 6
Carton contents (all instruments) 6
5. Preparations for use (all instruments) 7
Batteries 7
Preliminary test lead check 7
6. General operating instructions 8
General functions 8
LCD Display 9
Backlight operation 10
7. Test lead connections 11
Standard test leads 11
SP5 Switched probe (not MIT400, MIT480 and MIT40X) 11
8. AC/DC voltage and frequency measurements 12
9. Insulation resistance testing - general 13
Standard insulation resistance testing 13
Insulation resistance testing – timed modes ‘t’, PI and DAR 14
10. MIT40X testing 17
11. Continuity testing [] and buzzer [
12. Resistance measurements (k Range) 19
13. Capacitance measurements 20
Capacitance measurement procedure 20
Distance measurement by capacitance 20
14. Setup options 21
15. Saving , recalling and downloading test results. 23
Saving test results 23
Test results recall 23
PI and DAR recall. 24
16. Deleting test results 26
Procedure for deleting a single test result (refer to Figure 16) 26
Procedure for deleting all test results (refer to Figure 19) 27
Preparing your MIT430 or MIT485 for “Bluetooth” Communications 29
Preparing your MIT430 or MIT485 to your PC 29
Standard download operation 32
17. Battery and fuse replacement 32
Battery condition and replacement 32
Blown fuse indicator 33
18. Preventive maintenance 33
19. Specification 34
20. Basic and service errors 36
Basic error 36
Service error: 36
21. Accessories 37
22. Repair and Warranty 39
] 18
2
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 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.
3
2. Safety Warnings
mus t
N OTE
MIT400 series insulation testers
Safety Warnings and Precautions must be read and understood before the instrument is
used. They must
1
The circuit under test must be switched off, de-energised, securely isolated and
proved dead before test connections are made when carrying out insulation and
continuity tests.
Circuit connections and exposed-conductive-parts and other metalwork of an
2
installation or equipment under test must not be touched during testing.
The live circuit warning and automatic discharge are additional safety features,
3
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.
4
After insulation tests, capacitive circuits must be allowed to dischargebefore
5
disconnecting test leads.
The instrument should not be used if any part of it is damaged.
6
All test leads, probes and crocodile clips must be in good order, clean and with no
7
broken or cracked insulation.
Ensure that hands remain behind guards of probes/clips when testing.
8
National Safety Authorities may recommend the use of fused test leads when
9
measuring voltage on high-energy systems.
Replacement fuses must be of the correct type and rating. Failure to fit the correctly
10
rated fuse may result in a safety hazard and may cause damage to the instrument in
the event of an overload.
The battery cover m
11
be observed during use.
be in place whilst conducting tests.
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.
4
3. Symbols used on the instrument
F Caution: risk of electric shock
GCaution: refer to accompanying notes
Displayed on the LCD during an insulation test, warns that a hazardous
voltage may exist at the test lead probes also observe voltage discharges
to a safe level.
On battery cover see section 2.0 notes 10 and 11.
At terminals do not exceed rated input voltage.
Equipment protected throughout by Double Insulation (Class II)
Equipment complies with relevant EU Directives
Equipment complies with ‘C tick’ requirements
Do not dispose of in the normal waste stream
G>600 V Maximum input voltage 600 V rms
5
4. General Description
4.1 Case contents
There are important documents that you should read and keep for future reference.
Please complete the pre-paid 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.
4.2 Case contents (all instruments)
1 x MIT400 series instrument
1 x Hard carry case
1 x Red/black test lead set with clips
5 x AA (LR6) batteries fitted
1 x Warranty card
1 x Calibration certificate
1 x Owners CD manual
1 x SP5 remote switched probe (Not MIT400 &MIT480)
1 x Download Manager software CD (MIT430 and MIT485 only)
MIT400 storage with holster MIT400 storage with no holster
6
5. Preparations for use (all instruments)
5.1 Batteries
The Megger MIT400 series instruments are supplied with batteries fitted. When batteries
become exhausted, refer tosection17 for battery replacement.
Warning: Do not switch the instrument on or connect test leads with the battery cover
removed.
5.2 Preliminary test lead check
Functio nal 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.
Check continuity of the test leads by firmly shorting the leads together and read the
2.
test lead resistance measurement directly from the d isplay, which should be less than
1.0 .
Supply voltage
With the exception of voltage measurement range, 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.
7
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 MIT480, MIT481 and MIT485 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.
8
6.1 General functions
Black Test lead
connection
LCD screen
Test button and
lead null
Insulation lock
button
Insulation test
ranges
OFF positon
Resistance ranges
Capacitance (μF)
Figure 3 Main features (MIT430 shown)
Red test lead or
switched probe
Function
buttons
Battery/internal
fuse access
panel at rear
Voltage range
Result recall and
transfer
Insulation, PI test, DAR test
or timed test button
Store/last button
TRMS/DC button
Figure 4 Function buttons (MIT430 shown)
Up/down buttons
μA/s/V button
Next button
Buzzer on/off
Backlight button
Test button
9
6.2 LCD Display
Auxiliary digital display
Multifunction
analogue display
Continuity indicator
Lock indicator
Warning – refer to
user manual
Fuse blown indicator
Out of range
indicator
Lead null indicator
Figure 1 LCDdisplay
6.3 Voltage warning
If the voltage is greater than 25 V the meter automatically displays the voltage.
For MIT400, MIT405, MIT410, MIT420, MIT430 and MIT40X instruments, if a voltage greater
than 50V exists, testing will be a utomatically inhibited and voltage measurement will be
displayed.
For MIT480, MIT482, MIT485 instruments, if a voltage greater than 75 V exists, testing will be
automatically inhibited and a voltage measurement will be displayed. Voltages higher than 50
V will be indicated by a warning buzzer.
In continuity mode, if a voltage greater than 25 V exists, testing will be automatically inhibited
and voltage measurement will be displayed.
Units of parameters on
auxiliary display
Battery condition
indicator
Audible alarm indicator
TRMS indicator
Units of parameters on
main display
6.4 Backlight operation
All instrument displays are backlit. The backlight function can be selected at any time while
the instrument is switched on by pressing the BACKLIGHT [
The backlight function will switch off automatically after 20 seconds.
] button. Refer to figure 4.
10
7. Test lead connections
Test lead s co n ne c tions are as indicat e d in f igur e 2 which shows the te st le ad sockets at
the top of the instrument, as well as the switched probe socket and test lead.
Black test lead
connection
Figure 2 Testlead connections
Red test lead
connection
SP5 connection
7.1 Standard test leads
The Red/Black test lead set should be connected to the appropriate sockets on the top of the
instrument marked + and –, respectively. (see figure 2 )
Test probes and crocodile clips are supplied for connection to the circuit under test.
Fused test leads are available as an optional accessory.
7.2 SP5 Switched probe (not MIT400, MIT405, MIT480 and MIT40X)
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.
1.
Connect the SP5 probe to the instrument using the special 3-pole +ve socket (in place
of the RED test lead).
Select a suitable insulation resistance range.
2.
Press and hold down the SP5 probe button. The instrument will start an insulation
3.
resista nce test.
To end the test, release the probe test button.
4.
The SP5 remote switch probe replaces the standard red test lead. The test button on the
probe duplicates the test button operation on the instrument when insulation testing.
To operate the switch probe, connect the probe to the circuit to be tested and press and
hold down the button on the probe. The insulation test will commence. Releasing the button
will terminate the test.
The test lead resistance can be nulled for continuity testing. Refer to section 11.2
11
8. AC/DC voltage and frequency measurements
Note: Measured voltage must not exceed 600 V phase to earth or Phase to Phase
Frequency measurement is not available on MIT400, MIT405 and MIT480 models.
Procedure for measurement of volta ge and frequency
(Refer to Figure 5)
DC indicated
Screen B:
Analogue a.c. voltage
Screen A (a.c.)
displayed
Step 4:
Measured frequency
Voltage and frequency
display d.c. and voltage
display in d.c. mode
Step 5:
Result store button
Step 3:
TRMS/DC
TRMS indication
Measured a.c. voltage
(V or mV)
Test button
Step 2:
Connect test lead to
circuit under test
Step 1:
Selector switch
Note on TRMS measurement:
IN TRMS mode the MIT400 will measure both AC and DC components of the supply voltage (AC+DC).
In DC mode only the DC component is measured.
Rotate selector switch to the ‘V’ position.
1.
Connect test leads to the circuit under test.
2.
3.
‘TRMS’ is the default mode on power-up. Press the [TRMS] button to select DC or return to
TRMS if required.
The measured voltage will be displayed on the main digital scale in units of V or mV, as
4.
appropriate In TRMS mode, the measured frequency (Hz) will be simultaneously displayed on
the MIT410, MIT420, MIT430, MIT 481, and MIT 40X instruments (as shown on Screen A). See
Figure 5 Screen B
For MIT420, 430, 481 and 485, the measured result may be stored if required by pressing the
5.
‘STORE’ button. Refer to section 14 for further information.
Figure 5 Voltage and frequency measurement
for dc mode display.
12
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