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MIT417/2
User Manual
45 pgs4.59 Mb0

Megger MIT400/2, MIT405/2, MIT415/2, MIT417/2, MIT420/2 User Manual

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MIT400/2 Series
Insulation and continuity testers
User guide
2
User guide contents
1. Introduction 3
2. G Safety 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.
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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.
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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.
G refer to user instructions
F risk of electric shock
> 600 V
CATIV 600 V
g
600 V ac rms maximum between terminals, and between terminal and earth
IP54 Enclosure is dust proof and
protected against water splashes
f Fuse 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
6 6 6 6 6 6 6
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
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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
V
Trms Voltage AC/DC
500 V
Insulation test range –
Press & hold
button
500 V
L
Insulation test range with gate*–
Press & hold
L
to enable range when selecting test function with rotary knob (* where available)
W
Continuity measurement from 0.01W to
999 kW (automatic)
µF
Capacitance measurement ( automatic)
L
Insulation test lock - Press and L to
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
L
to 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
F
Hazard voltage warning Delete test results
G
Warning - Read user manual Bluetooth® enabled
z
Lead Null is enabled Battery condition
DW
Difference between two ohms measurements
f
Fuse fail warning
G
F
z
f
k
M
G
0
+35
100.01
8100.1
61004100
2100
-1510
9
8
7
6
5
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
zkAm
µ
H
k V
k
ft
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
G
G
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
A
R
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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