Megger MIT1525, MIT1025 Operating Manual

MIT515, MIT525, MIT1025, MIT1525 5 kV, 10 kV & 15 kV Insulation Resistance Testers

USER MANUAL

G SAFETY WARNINGS

Safety warnings must be observed during use:

• The circuit under test must be switched off, de-energised, isolated and checked to be safe before insulation test connections are made. Make sure the circuit is not reenergised whilst the instrument is connected.

• Only 15 kV rated Megger test leads with plug inserts of 75 mm must only be used on the MIT1525. Lead integrity can be

verified by momentarily shorting clips together at the lowest test voltage range.

• Circuit terminals must not be touched during an insulation test or before suitable grounding of the unit under test is in place in line with safe working practices.

• The functional earth terminal on MIT1525 must be connected to provide a resistance path to ground, or a uni-potential bonding point.

• After completing a test, capacitive circuits must be completely discharged before disconnecting the test leads. Capacitive charges can be lethal.

• Tested items must be firmly shorted out with a shorting link, after discharge, until required for use. This is to guard against any stored dielectric absorption charge subsequently being released thereby raising the voltage to potentially dangerous levels.

• The voltage indicator and automatic discharge features must be regarded as additional safety features and not a substitute for normal safe working practice.

• It is rare, but in certain circumstances, breakdown of the circuit under test may cause the instrument to terminate the test in an uncontrolled manner, possibly causing a loss of display while the circuit remains energised. In this event, the unit must be turned off and the circuit discharged manually.

• Test leads, including crocodile clips, must be in good order, clean and with no broken or cracked insulation.

• The instrument must not be used if any part of it is damaged.

• Insulation testing in wet conditions might be hazardous. It is

recommended that this instrument is not used in these circumstances. If this is unavoidable, the user must take all necessary precautions.

• This instrument is not intrinsically safe and must not be used in hazardous atmospheres.

• If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be impaired.

• Switch the instrument OFF, and disconnect any AC source, measurement leads, and all other equipment before opening the case to change the battery. The instrument must not be operated with the case open. DANGER! Hazardous voltages are exposed with an AC source connected and the case open.

BATTERY WARNINGS

• Do not disassemble or modify the battery. The battery contains safety and protection devices which, if damaged, may cause the battery to generate heat, rupture or ignite.

• Never heat the battery in a fire or otherwise.

• Do not pierce or damage the battery in any way

• Do not subject the battery to strong impacts/shocks.

• Do not expose the battery to water, salt water or allow the

battery to get wet.

• Never short circuit, reverse polarity or disassemble the battery pack.

• In the event of a battery cell leaking, do not allow the liquid to come into contact with the skin or eyes. If contact has been made, wash the affected area with copious amounts of water and seek medical advice.

• Keep cells and batteries out of reach of children

• Seek medical advice if a cell or battery has been swallowed.

• Do not leave a battery on prolonged charge when not in use.

• Retain the original product literature for future reference.

NOTE:

THE INSTRUMENT MUST ONLY BE OPERATED 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.

Symbols used on the instrument

G Caution: refer to user manual F Caution: risk of electric shock

Equipment protected throughout by Double Insulation.

Line Power / mains

c Equipment complies with current EU directives.

Equipment complies with current “C tick” requirements.

Do not dispose of in the normal waste stream.

g Functional Earth

Universal Serial Bus (USB)

CAT IV

Measurement category IV: Equipment connected between the origin of the low-voltage mains supply and the distribution panel.

CATIV applies to voltage measurement function of these instruments.

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.

WEEE Directive

The crossed out wheeled bin symbol on the instrument and on the batteries is a reminder not to dispose of them with general waste at the end of their life.

Megger is registered in the UK as a Producer of Electrical and Electronic equipment. The registration no is; WEE/HE0146QT.

Users of Megger products in the UK may dispose of them at the end of their useful life by contacting B2B Compliance at

www.b2bcompliance.org.uk or by telephone on 01691 676124.

Users of Megger products in other parts of the EU should contact their local Megger company or distributor.

Battery Disposal

Batteries in this product are classified as Industrial Batteries under the Batteries Directive. Please contact Megger Ltd for instructions on the safe disposal of these batteries.

For disposal of batteries in other parts of the EU contact your local distributor. Megger is registered in the UK as a producer of batteries. The registration number is BPRN00142.

For Further information see www.megger.com

Table of contents and index

General description.................................................................. 5!

Features................................................................................... 5!

Preparations for Use................................................................ 7!

Initial instructions.................................................................. 7!

Power lead and battery charging ......................................... 7!

Functional verification .......................................................... 7!

Calibration............................................................................ 7!

Storage................................................................................. 7!

Operating Instructions.............................................................. 7!

General operation ................................................................8!

Breakdown vs. burn mode ................................................... 9!

Voltmeter.............................................................................. 9!

Reset Default Settings ......................................................... 9!

Instrument Control................................................................ 9!

Initial setup ..................................................................... 10!

Lock Voltage................................................................... 10!

Alarm setting................................................................... 10!

Recording temperature................................................... 10!

Breakdown mode / burn mode ....................................... 11!

Running an insulation test .............................................. 11!

Memory functions and downloading ............................... 12!

Real-time output during insulation tests ......................... 13!

PowerDB............................................................................... 14!

Interfacing MIT ranges to PowerDB ............................... 14!

Import/Live Stream Control Application ........................ 15!

Battery indicator............................................................... 15!

On screen error reporting ............................................... 16!

Measurement Modes .........................................................17!

‘Spot’ IR test ................................................................... 17!

Timed IR test .................................................................. 17!

DAR and PI Insulation Tests .......................................... 17!

Dielectric Discharge test................................................. 18!

Step Voltage Test........................................................... 19!

Ramp voltage test........................................................... 20!

Measurement Techniques.................................................. 21!

Understanding Measurement Currents .......................... 21!

Insulation measurements above 100 GΩ ....................... 22!

Terminals........................................................................ 23!

GUARD terminal, screened leads................................... 23!

Preventive Maintenance ........................................................24!

Cleaning.......................................................................... 24!

Care of the instrument ....................................................24!

Leads .............................................................................. 24!

Battery Care....................................................................24!

Replacing the battery...................................................... 24!

MIT1525 battery replacement instructions:....................... 25!

Technical Specification .......................................................... 26!

Electrical specification........................................................ 26!

Environmental Conditions .................................................. 28!

GENERAL SPECIFICATION.............................................. 28!

Repair and Warranty.............................................................. 29!

Calibration, Service and Spare Parts ................................. 29!

Returning product to Megger UK & USA service centres...29!

Approved Service Centres ................................................. 30

Accessories, Equipment and Spares…………………………..31

General description

The new range of Insulation Resistance Testers (IRT) consists of four models; an entry level 5 kV and three fully featured units, one 5 kV, one 10 kV and one 15 kV.

Features

• Max resistance is 10 TΩ (5 kV), 20 TΩ (10 kV) and 30 TΩ (15 kV)

• MIT515 with IR, IR(t), PI and DAR

• MIT525, MIT1025, MIT1525 diagnostic and over voltage

tests - PI, DAR, DD, SV and ramp test.

• Operate and charge on line power/mains (except during actual test)

• Light weight Li ion battery

• CATIV 600 V safety rating (MIT515, MIT525, MIT1025)

CATIV 1000 V safety rating (MIT1525) – applies to voltmeter function

• Advanced memory with time/date stamp

• DC and AC voltmeter (30 V to 660 V)

• Large LCD display with backlight

• Download of saved results and logs via isolated USB cable

(MIT525, MIT1025, MIT1525 only)

• PowerDB Lite software included with MIT525, MIT1025 and MIT1525.

Instrument Controls and Indicators

1. Positive (+) terminal

2. GUARD terminal

3. Negative (-) terminal

4. USB device interface

5. Four arrow buttons and OK button

6. TEST button with associated HV warning lamp

7. Backlight button

8. Central rotary switch

9. Save button – MIT525, MIT1025, MIT1525

10. Test mode rotary switch

11. LED indicating line power / mains

12. Display

13. Power socket

14. Functional earth terminal: 15 kV only

User lock voltage

Delete records

Timer

Download via USB

Save

Filter

Open records

Alarm

Battery

Breakdown mode

Ramp test

Burn mode

Danger HV

Refer to manual

Fuse

Noise detected

Preparations for Use

Initial instructions

• Remove instrument, power lead and pouch from the

packing box.

• Clip the test lead pouch to the lid.

• Open the lid and familiarise yourself with the layout and

position of the IEC 60320 power inlet on the left side of the panel. An isolated USB socket is found on the right side of the instrument.

• Unpack leads and pack them into the lead pouch.

• Read the product manual, especially the warnings.

• A quick reference is provided in the instrument lid.

• Keep the original packaging for re-use.

Power lead and battery charging

• If the power lead supplied is not suitable for your

line/mains connection, do not use an adaptor. Always use a power lead fitted with the correct plug.

• Supply voltage: 90 to 265 V rms ac at 50/60 Hz.

• A green LED illuminates when line power/mains is

present.

• The battery will charge as long as the mains supply is

connected, except when a test is in progress.

• For optimum battery life, charge the battery after each

use. Full charge duration is up to 2½ hours but a first charge time of 3 hours is advised.

• The battery must be charged between 0 ºC and 40 ºC

ambient temperature. If the battery detects a temperature outside this range the battery symbol will flash.

Power lead connection table

Connection

UK/International

USA

Earth/Ground

Yellow/Green

Green

Neutral

Blue

White

Live (Line)

Brown

Black

Functional verification

Simply turning on the instrument will initiate a start-up process and the display will respond. If an error is detected ‘Err’ will be displayed with an associated error number.

Calibration

The MIT515, MIT525, MIT1025 and MIT1525 are supplied with a calibration certificate which is automatically generated as part of Megger’s final test procedure.

UKAS accredited calibration certificates are available from Megger but this service is chargeable.

Storage

Instruments should be stored in storerooms which meet the storage temperature and humidity specifications listed in this document. If charging is incorporated in the storeroom the room must be well ventilated.

Operating Instructions

General operation

The MIT515, MIT525, MIT1025, MIT1525 Insulation resistance testers (IRTs) are primarily controlled by two rotary switches and a TEST button used to start and stop a test (see section entitled, ‘Instrument Control and Indicators’). The central rotary switch includes an ‘OFF’ position; the instrument switches on by rotating the switch either clockwise or anticlockwise from this position. A range of test voltages for insulation resistance tests up to 5 kV for MIT515/MIT525,10 kV for MIT1025 and 15 kV for MIT1525 are available, including a user selectable voltage range which can be set between 40V or 100 V and 5000 V, 10000 V or 15000 V depending on model. The ‘lockable’ test voltage range can be adjusted in the settings function.

The settings function is indicated by a spanner symbol and facilitates lock voltage, low resistance alarm, temperature, time/date adjustment. A light blue coloured section of the rotary switch denotes memory functions; open records, download via USB and delete records. A dedicated save button is provided on the MIT525, MIT1025 and MIT1525 models and all models have a backlight button.

A second rotary switch controls the insulation test mode providing for the following tests:

• All models have basic insulation resistance IR, timed

insulation resistance IR(t), Dielectric Absorption Ratio (DAR) and Polarisation Index (PI) tests.

• MIT525, MIT1025, MIT1525 have additional tests;

Dielectric Discharge (DD), Step Voltage (SV) and ramp test.

A cluster of directional buttons and an OK button are used in settings and memory functions. The up/down arrows also enable the test voltage to be adjusted during a test. Prior to the start of an IR or IR(t) test, holding down the left arrow button with a voltage level selected on the central rotary switch will activate burn mode. Burn mode is deactivated if the

voltage range or mode is changed or by pressing the right arrow/breakdown button.

Instrument controls are simple to operate. The central rotary switch incorporates the OFF position. The left hand rotary switch selects insulation test type (test mode switch). The TEST button starts and stops a test.

Four arrow buttons and OK facilitate adjustment and selection of settings, voltages and modes. Breakdown/burn modes are set using the left and right arrow buttons. Backlight and save functions are dedicated buttons. All models have backlight and the MIT525, MIT1025 and MIT1525 have the Save button.

Breakdown vs. burn mode

In breakdown mode insulation tests are automatically stopped when a fault causes the applied voltage to drop rapidly. Burn mode IR tests ignore breakdown and continue to test the insulation and are therefore destructive tests. Burn mode is used to purposely create a carbon track in insulation to facilitate fault location. Burn mode only operates at test voltages of 500 V and above.

Voltmeter

A voltmeter is incorporated in the instrument and measures AC/DC voltage from 30 V to 660 V. Frequency (Hz) is measured and displayed for AC voltages. Voltmeter mode is activated by switching to ‘V’ mode as illustrated.

Positive and negative terminals are used for the voltmeter function; do not connect the GUARD terminal when in voltmeter (V) mode.

To assist user safety, the instrument will automatically switch to voltmeter mode if a voltage of 50 V or more is connected to the terminals. The measured voltage will be displayed accompanied by an intermittent beeper to warn the user that a dangerous voltage exists.

For further explanation see, “Running an Insulation Test” on page 11.

Reset Default Settings

Remove AC source, press OK, backlight buttons and switch main rotary switch from OFF to setting icon.

Instrument Control

Initial setup

It is important to setup the Real Time Clock (RTC) on models MIT525, MIT1025 and MIT1525 to ensure that records saved in the instrument are time/date stamped correctly. The MIT515 does not require time/date setting. The RTC has a separate battery to maintain settings even when the primary battery is removed.

To set the clock and date, select the settings function on the central rotary switch and turn the mode rotary switch to IR. Navigate using the left/right arrows to where the time and date is displayed.

Set the time using the up and down arrows. Change the hours and minutes then press OK to save.

Select the day/month format required, i.e. d:m for day:month or m:d for month:day and press the right arrow button, then set the date and press OK to save. A tick on the left of the display indicates that a setting is saved, a cross is displayed during adjustment indicates that it is not set. Exit settings by changing the central rotary switch to a different position.

Lock Voltage

The user selectable ‘lock’ voltage range is set by adjusting the displayed voltage using the up and down arrow buttons. When

the desired voltage is displayed, it is saved, by pressing the OK button. The setting does not change even if the instrument is switched off.

Alarm setting

A low resistance alarm sounds when the resistance level of an insulator reaches the alarm, assuming alarm has been activated. The default alarm setting is 500 kΩ and inactive (X is displayed on the right of the display). Set central and mode rotary switches to the settings and IR positions respectively. Press the right arrow button once. The low resistance alarm can be set at the default value by simply pressing the OK button, or changed to a different alarm resistance level using the up/down arrow buttons and save it by pressing OK.

Recording temperature

The MIT525 and MIT1025 are able to record insulation temperature measured by an independent thermometer. If you do not wish to record temperature do not change the default setting or reset it if it was previously set.

Move the central rotary switch to point to settings and press the right/left arrow buttons until ‘tº ---‘ is displayed. The default setting is no temperature record. This can be changed by pressing up or down arrows to select either ºF or ºC temperature entry. Pressing OK will confirm the setting and result in a prompt for temperature to be entered whenever the save button is pressed after completing any test. Up and down arrows facilitate temperature entry in 1 ºC increments / decrements.

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