MIT400/2 Series Insulation and continuity testers User guide
User guide contents 2. G Safety Warnings 4 17. Battery and fuse replacement Battery condition and replacement Blown fuse indicator 3. Symbols used on the instrument 5 18. Preventive maintenance 33 4. General description Unpacking the carton Carton contents (all instruments) 6 6 6 19. Specification 34 Preparations for use (all instruments) Batteries Preliminary test lead check 7 7 20. Basic and service errors Basic error Service error: 36 36 36 21. Accessories 37 6.
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.
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.
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.
3. General Description 3.1 Case contents There are important documents that you should read and keep for future reference. 3.2 Case contents (all instruments) 1 x MIT400/2 series instrument 1 x Hard carry case 1 x Red/black test lead set with clips 3 x Red/Blue/Black 2.
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.
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.
5.2 Display contents Storage and downloading symbols 6 7 4100 +10 6100 5 0 +20 8100.1 2100 +30 9 -10 8 -1510 GW Mk W kVs MkWV kft H zkµ mA 8 FG Warning and Advisory symbols Symbol GW, MW, kW W, V , mV , Units of measurement A, mA, Hz, nF, uF Primary digital readout LU F G z DW MIT400/2 100.
5.3 Terminal overview 2 terminal connection 2 terminal connection + Guard MIT400/2 3 terminal connection www.megger.
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.
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.
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.
Terminal layout - 3 Terminal instrument: - Figure 5 3 Terminal connection example: B / Ring / Live CAT III 600 V g E / Ground / Earth A T A / Tip / Neutral E G G B R - Figure 6 7.3.
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.
8. Voltage and frequency measurements V 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.
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.
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.
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: made.
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: 100 10 1 0.1 0.01 8 GW G 0 V GW - 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.
Note: This function is Independent of the Buzzer ON/OFF mode. 9.1.5 Insulation test LOCK To lock the insulation ON: 1. Select one of the test voltages on the MW measurement mode using the range knob MW . 2. Connect the test leads to the circuit to be measured. 3. Press and hold down the TEST button. Whilst the test is running, press the LOCK button. Release the LOCK and TEST buttons. The LOCK symbol should be displayed and the test will continue to run.
9.2 Variable voltage insulation testing (MIT430/2, MIT485/2, MIT2500) The MIT430/2, MIT485/2 and MIT2500 have a variable voltage mode of insulation testing. Indicated by the symbol V . The voltage can be selected between the bottom and top test voltages on the instrument. This value can be changed in 1V increments to 100V and 10V increments above 100V The test voltage is configured in SETUP, see section 13. All insulation test functions work for this test mode as they do for a standard test voltage.
The small digital readout should change from displaying the selected test range (in Volts) to PI, to DAR, T and INS, as below: 10 1 0.1 100 0.01 GW 8 0 10 1 0.01 GW 0 MW 0.1 100 0.01 1 0 8 GW 1 MW 10 1 0.1 0.01 GW 0 8 10 100 0.1 8 100 MW MW - Figure 24 4. Select the DAR function. 5. Press and release the TEST button to start the test. The display will show a count-down timer and the current insulation value, as above: 100 10 1 0.01 GW 8 0.
At the end of the test period the MIT will make a second measurement and display the results as a ration of the 1st and 2nd measured values, as below: 100 10 1 0.1 0.01 GW 8 0 Note: Second measurement is logged at 0 seconds. Again, this is not stored in memory unless the "SAVE" button is pressed at the completion of the test, see section 9.3.4 - Figure 27 9.3.2 Polarisation Index The same method as in 9.3.1 above is used. Only the test times change. 9.3.
9.4.1 Using 2 test leads on a 3 terminal instrument A measurement can be made across any of the three pairs, as long as the pair Is displayed In the screen. 1. Ensure instrument is in the A-B mode indicated in the display, as below: - Figure 29 For details of changing the configuration see section 7.3 - 3 terminal connections. 2. Connect test leads to the RED/BLACK test sockets only. 3. Select one of the INSULATION measurement voltages on the range knob MW . 4.
9.4.2 Using 3 test leads All three connections can be connected to the circuit under test, for example: Electrical testing Telecommunications USA Telecommunications EU A (T) = Neutral T = Tip A=A B (R) = Live R = Ring B=B E (G) = Earth E = Earth E=E The measurement should default to Live - Neutral (B-A) 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. 9.
10. Continuity testing W Continuity testing operates over the range 0.01 ohms to 999 kohms. The MIT will auto-range across the full range from 0.01 ohm to 1 Mohm. The analogue arc will auto range as below: 0 - 10 ohm 0 - 1 Mohm Test current automatically adjusts for the range selected by the instrument. Test currents adjust as below: 0.01 to 3.99 ohms = 200 mA (or 20 mA depending on settings - see section 13 SETUP) 4.00 to 999 kohms = 20 mA to 2µA The test operates at 4.
10.2 Single or bi-directional testing The default setting is for a single direction continuity test. This can be changed to a bi-directional test in SETUP. see section 13. First test: Red terminal = 4.5Vdc, Black terminal = 0Vdc Second test: Red terminal = 0Vdc, Black terminal = 4.5Vdc As with the single test, the Bi-directional test the measurement is automatic. The measurement displayed is the higher of the two directional measurements.
10.4 Buzzer PASS/FAIL threshold The MIT will sound a buzzer If the measured value is less than the threshold configured in SETUP. Refer to SETUP section 13. 10.5 Buzzer ON/OFF The buzzer can be disabled by pressing the BUZZER button on the keypad as below: - Figure 35 Note: This will disable the buzzer sound but NOT the warning alarms 10.6 PASS / FAIL limit alarm A Pass/Fail threshold can be configured in setup, such that the buzzer sounds when the value is below a selected value.
11. Capacitance measurements (Except MIT400/2, 410/2) The MIT400/2 can measure circuit or component capacitance. The test is automatic and starts the test immediately on connection of a circuit. If capacitance is large the circuit can take time to charge. During this charge time the display will show "- - -". On completion of the test the display will show the measured capacitance, and under range symbol "<1.0 nf" or an over range symbol >10uF". 11.1 Capacitance measurement procedure (2 terminals) 1.
12. Saving, recalling and downloading test results. (MIT420/2, MIT430/2, MIT481/2, MIT485/2 and MIT2500) 12.1 Saving test results After completing any test, the result remains displayed on the screen for one minute. During this time the result may be saved in memory and recalled later. Procedure for storing test results: 1.
12.2 Test results recall (MIT420/2, MIT430/2, MIT481/2, MIT485/2 and MIT2500) All stored test results may be recalled to the screen. 1. Turn the instrument ‘ON’ by rotating the selector switch to the recall (RCL) position. - Figure 42 2. The latest unique test result identification number will be displayed. Where no results have previously been stored, the display will indicate this by three dashes. 3.
12.3 Deleting test results (MIT420/2, MIT430/2, MIT481/2 and MIT485/2 only) Stored test results may be deleted singularly or all together. Procedure for deleting a single test result 1. Turn the instrument ‘ON’ by rotating the selector switch to the delete position. 2. The latest test result will be displayed. Where no results have previously been stored, the display will indicate this by three dashes. 3. Press ‘OK’ to delete the displayed test result. 4.
- figure 44 Pre-paired screen Unpaired screen The MIT can pair with up to 12 devices, after which further pairing will over-write the currently displayed pair. To select a different paired device from that shown, use the UP/DOWN arrow keys. If the MIT is already paired to the PC, go to (12.6) below. 3. Press and hold the yellow TEST button for longer than 1 second to start the pairing process. - Figure 45 4. The instrument will search for Bluetooth® devices nearby.
- Figure 46 4. Select the Blue download button. The Download dialog box will be displayed. - Figure 47 5. Turn the MIT rotary knob to the PC position. 6. Press the TEST button on the MIT to commence the download. 7. On completion of the download the MIT will display “End”. A CSV file will appear in the Download manager window. This can be opened using: The Megger CSV viewer A proprietary CSV viewer Windows® XLS (opens with no header conversion.
13. SETUP Configuration options Operator SETUP allows the MIT to be customised to suite application or operator preferences. To enter SETUP, select the option with the rotary knob. The following options are available: 13.1 SETUP navigation 1. Press the TEST button to scroll through the SETUP options. 2. When the display shows the required SETUP option, press the UP or DOWN arrows to change the value for that option. The LOCK symbol will flash to indicate the value has been changed from the saved setting.
14. Technical Specifications All quoted accuracies are at +20 °C. Insulation: Test voltage Nominal: MIT400/2 250 V, 500 V, 1000 V MIT410/2, 420/2,430/2 50 V, 100 V, 250 V, 500 V, 1000 V Insulation accuracy 50 Volts. 10 GW ± 2% ± 2 digits ± 4.0% per GW 100 Volts. 20 GW ± 2% ± 2 digits ± 2.0% per GW 250 Volts. 50 GW ± 2% ± 2 digits ± 0.8% per GW 500 Volts. 100 GW ± 2% ± 2 digits ± 0.4% per GW 1000 Volts 200 GW ± 2% ± 2 digits ± 0.2% per GW Service Error: BS EN 61557-2 (2007) 50V, ±2.
Frequency: Frequency measurement range 45-450Hz Frequency measurement accuracy ±0.5% ± 1digit (100 Hz to 450 Hz) unspecified Capacitance measurment: MIT420/2, MIT430/2 Capacitance measurement: 100 pF to 10 μF Capacitance measurement accuracy ± 5.
15. Battery and fuse replacement 15.1 Battery condition and replacement The battery condition indicator is displayed at all times that the instrument is switched on, as below: 100%, 75%, 50%, 25% and low, as below: 100% 75% 50% 25% Low Replacement battery types are: 6 x LR6 (AA), 1.5 V Alkaline, or 6 x 1.2V NiMH WARNING: Do NOT use AA size LiON (Lithium Ion) rechargeable cells as these are 3.4V each and could permanently damage the instrument.
15.4 Blown fuse indicator The blown fuse indicator is shown below: 2 00 4 00 6 00 f 8 00 100 0 0 W mA z W - Figure 48 This symbol operates on the continuity [W] range. The symbol indicates that one of the fuses in the instrument has failed. 15.5 Fuse replacement procedure 1. Switch off the instrument and disconnect the instrument from any electrical circuits. 2. Disconnect all test leads from the instrument. 3. Remove the rear fuse cover.
Repair and warranty If the protection of an instrument has been impaired it should not be used, but sent for repair by suitably trained and qualified personnel. The protection is likely to be impaired if, for example, the instrument shows visible damage, fails to perform the intended measurements, has been subjected to prolonged storage under unfavourable conditions, or has been exposed to severe transport stresses.
MIT400/2 www.megger.
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