Megger MFT70 Operating Manual

MFT70-US

Multifunction Tester With On - board memory

User Manual

Contents

SAFETY WARNINGS 5

Live Ground safety precautions ........................................................................................................................6

Symbols used on the instrument are: ..............................................................................................................7

Introduction 8

Overview .........................................................................................................................................................8

Front panel and controls ..................................................................................................................................8

Display .............................................................................................................................................................8

Display symbols ..............................................................................................................................................9

Waste electrical and electronic equipment......................................................................................................10

Battery and fuse location, ﬁtting and replacement .........................................................................................10

To replace batteries or fuse: ...........................................................................................................................10

For battery replacement: ................................................................................................................................10

For fuse replacement .....................................................................................................................................10

Rechargeable batteries and battery charging ..................................................................................................10

To charge the batteries:..................................................................................................................................11

Operation 12

General operation – all models.......................................................................................................................12

Switching on ...............................................................................................................................................12

Switching off ..............................................................................................................................................12

Backlight .....................................................................................................................................................12

Test buttons .................................................................................................................................................12

Test button lock ..........................................................................................................................................12

Mode button functions ............................................................................................................................13

Test inhibit .....................................................................................................................................................13

Insulation .......................................................................................................................................................13

Continuity ....................................................................................................................................................13

GFCI testing ...................................................................................................................................................13

Ground testing ..............................................................................................................................................13

Battery exhausted ..........................................................................................................................................13

Voltage, frequency, current and temperature measurement............................................................................14

Making a voltage measurement .....................................................................................................................14

OR if using the mains plug lead SAI10:...........................................................................................................14

Frequency measurement ................................................................................................................................15

Phase rotation ................................................................................................................................................15

Leakage current measurement ......................................................................................................................15

Temperature measurement ............................................................................................................................15

Switch probe .................................................................................................................................................15

Continuity / resistance measurement ..............................................................................................................16

Nulling test lead resistance (up to 9.99 ohms) W .........................................................................................16

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Contents

To null test leads: ........................................................................................................................16

Making a continuity measurement .................................................................................................................17

Storing / downloading results .........................................................................................................................17

Continuity Buzzer ON/OFF..............................................................................................................................17

Switch probe (SP5) .........................................................................................................................................18

Buzzer threshold ............................................................................................................................................18

Measurement methods and sources of error ..................................................................................................18

Method of measurement .............................................................................................................................18

Possible sources of error ...............................................................................................................................18

500

Insulation resistance

Making an insulation measurement ...............................................................................................................19

Insulation test lock .......................................................................................................................................19

Measurement methods and sources of error ..................................................................................................20

Ground Fault Current Interrupt (GFCI) testing ................................................................................................20

.............................................................................18

Function button options ....................................................................................................................20

Ramp test ....................................................................................................................................................20

Making a measurement ...............................................................................................................................20

Touch voltage display ...................................................................................................................................21

Measurement methods and sources of error ................................................................................................21

Useful information .......................................................................................................................................22

Ground resistance measurement ....................................................................................................................22

Connection terminals ...................................................................................................................................22

Touch voltage limit .......................................................................................................................................22

Making a measurement - two pole resistance measurement ........................................................................22

Making a measurement – three terminal resistance measurement ...............................................................23

Making a measurement – three terminal resistance measurement using ART ...............................................24

Two-clamp stake-less measurement .............................................................................................................25

Setup options 26

Warning messages .........................................................................................................................................27

Startup warnings ........................................................................................................................................27

Battery .........................................................................................................................................................27

Battery charger ............................................................................................................................................27

Fuse warning ...............................................................................................................................................27

Invalid rotary switch setting .........................................................................................................................27

Continuity test .............................................................................................................................................27

Insulation test ..............................................................................................................................................27

GFCI Test ....................................................................................................................................................27

GFCI range selection errors ..........................................................................................................................27

Test will not start ........................................................................................................................................28

Sending, Storing, Deleting and Recalling Test Results......................................................................................29

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Contents

Folders: ........................................................................................................................................................29

Circuit type: .................................................................................................................................................29

Insulation: ....................................................................................................................................................29

GFCI: ...........................................................................................................................................................30

Ground testing: ...........................................................................................................................................30

Storing Test Results in the internal memory ....................................................................................................30

Deleting Test Results from the internal memory ............................................................................................30

Recalling Test Results to the display ..............................................................................................................31

Sending stored test results via Bluetooth® ....................................................................................................31

Sending individual (Blobbing) test results......................................................................................................31

Continuity testing ........................................................................................................................................32

GFCI testing .................................................................................................................................................32

Ground testing ...........................................................................................................................................32

Bluetooth® Pairing .........................................................................................................................................33

Bluetooth® Pairing (PC or Laptop) ................................................................................................................33

General Information 34

Installation category deﬁnitions ....................................................................................................................34

Safe working practice ..................................................................................................................................34

Cleaning and maintenance ..........................................................................................................................34

Ground resistance testing – Basic principles ....................................................................................................35

Principle of operation (three-terminal resistance measurement) ....................................................................35

Principle of operation (three-terminal resistance measurement using ART) ....................................................35

Principle of operation (two-clamp stake-less resistance measurement) ..........................................................36

General Speciﬁcation .....................................................................................................................................37

Repair and Warranty ....................................................................................................................................39

CALIBRATION, REPAIR AND SPARE PARTS .....................................................................................................39

Deceleration of Conformity .............................................................................................................................

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SAFETY WARNINGS

Safety warnings and precautions must be read and understood before the instrument is used. They must be observed during use.

Warnings:

• The circuit under test must be switched off, de-energised and isolated before test connections are made when carrying out insulation and continuity tests.

• Continuity of protective conductors and Grounded equipotential bonding of new or modiﬁed installations must be veriﬁed before carrying out an Ground fault loop impedance test, GFCI or Ground testing

• Do not touch circuit connections and exposed metalwork of an installation or equipment under test. Under fault conditions the system Ground could become hazardous live.

• Do not touch the Ground stakes, test leads and their terminations (including connections to the Grounding system under test) if an installation Ground fault can arise, unless adequate precautions are taken.

• The ‘live circuit warning’ and ‘automatic discharge’ functions are additional safety features and should not be regarded as a substitute for normal safe working practices.

• Do not move the rotary switch positions while a test is in progress.

• Do not operate the instrument or connect it to any external system if it shows any visible signs of damage or if it has been stored for prolonged periods in unfavourable conditions.

• Do not operate the instrument or connect it to any external system if the battery compartment or casing is open or any parts of the case (including keypad, selector switch, display window, etc.) are missing.

• Always disconnect the instrument from all systems while batteries are being changed or the fuse replaced

• Do not replace rechargeable cells in the instrument with non-rechargeable “dry” cells and attempt to charge the cells. This can cause explosion or ﬁre.

• Do not operate charging equipment supplied with the instrument in damp or wet environments or outdoors. All test leads must be removed from the instrument while charging.

• After insulation tests, capacitive circuits must be allowed to discharge before disconnecting test leads. Locking the insulation test ON should only be used where there is no risk of a circuit holding a charge.

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

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

• All test leads supplied with the instrument form part of the measuring circuit of the instrument. They must not be modiﬁed or changed in any way, or be used with any other electrical instrument or appliance.

• A plug severed from the power cord MUST be destroyed, as a plug with bare conductors is hazardous in a live socket outlet.

• Ensure that hands remain behind guards of probes/clips when testing.

• U.K. Safety Authorities recommend the use of fused test leads when measuring voltage on high energy systems.

• Replacement fuses must be of the correct type and rating.

• Failure to ﬁt the correctly rated fuse will result in damage to the instrument in the event of an overload.

• Special precautions are necessary when operating in situations where “live” Grounds may be encountered: isolation switches and fuses (not supplied with this instrument) must be used.

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SAFETY WARNINGS

• Special precautions are necessary when working near high tension systems (MV and HV): rubber gloves and shoes (not supplied with this instrument) should be worn.

• Special precautions are necessary when working in wet conditions or in agricultural areas: observe the local safety standards and take all necessary special precautions applicable to the particular location and do not touch the test leads with bare hands.

Live Ground safety precautions

A ‘Live’ ground is one that carries current from the mains supply, or could do so under fault conditions. The following warnings apply in addition to those listed previously.

Warnings:

• All persons involved must be trained and competent in isolation and safety procedures for the system to be worked on. They must be clearly instructed not to touch the Ground electrode, test stakes, test leads, or their terminations if any ‘Live’ Grounds may be encountered. It is recommended that they wear appropriate rubber gloves, rubber soled shoes, and stand on a rubber mat.

• The Ground electrode under test should be isolated from the circuit it is protecting before testing commences. If this is not possible, ART (attached Rod Technique) may be used to measure electrode resistance.

• The instrument terminals should be connected to the system under test through isolation switches that are rated to handle the likely maximum fault voltages and currents that could be encountered at the installation. The isolation switch must be open whilst any personal contact is made with the remote test stakes, or the connecting leads, e.g. when changing their position.

• The instrument terminals should be connected to the system under test through fuses that are rated to handle the likely maximum fault voltages and currents that could be encountered at the installation.

Note: This instrument must only be operated by suitably trained and competent people.

Users of this equipment and/or their employers are reminded that 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 constructed in accordance with the HSE guidance not GS38 ‘Electrical Test Equipment for use by Electricians’ should be used .

This instrument is internally protected against electrical damage when used for the purposes of testing low voltage electrical installations as deﬁned herein. If used in a manor other than those deﬁned in this user guide, the protection capabilities could be impaired with potential risk to the operator and the instrument.

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Symbols used on the instrument are:

SAFETY WARNINGS

> 600 V

f c

Caution: Refer to accompanying notes

Maximum 300 V a.c. CAT IV to Ground

Maximum nominal system voltage of 600 V

Instrument protected by 2 x F2 1000 V 30 kA fuses

Equipment complies with current EU Directives

This equipment should be recycled as electronic waste

Equipment complies with ‘C tick’ requirements

12 V DC charger socket

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Introduction

Congratulations on your purchase of a genuine Megger Multifunction tester. The MFT70 series Multi-function tester is a compact instrument designed to perform all of the functions required by the electrical contractor to fully test domestic, commercial and industrial wiring. Specially designed to comply with modern US International wiring regulations and standards, the MFT70 may be used on all single and three phase systems with rated voltages up to 300 V AC rms to ground.

Overview

Front panel and controls

Display

Test button Lead Null

Test lock Setup selector Results store

Mode

Display backlight

Display

Primary functions

Secondary functions

Touch voltage contact point

Test button Lead Null

Test lock Setup selector

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Display symbols

Symbol Meaning Symbol Meaning

Test function locked on (also used to indicate a change is saved in setup)

Warning triangle – instruction to refer to this user guide

Introduction

UL = 50V

AUTO

Test lead null active

Touch voltage limit (and Ground test voltage) set to 50 V (change setup)

Buzzer enabled NiMH

GFCI test in AUTO mode >100 V

Type AC GFCI selected Rp (Rs)

Type A GFCI selected Rc (RH)

Type S GFCI (Type AC)

Type S GFCI (Type A)

Type B GFCI selected

Fast or Full RAMP test selected Bluetooth® enabled

Fuse blown

Battery indicator

Battery type set to rechargeable NiMH Change in “Battery” on page 27

Indicates that the ground noise voltage exceeds the instrument measurement capability (test is inhibited)

Potential stake (P stake) resistance exceeds range for accurate measurement

Current stake (C Stake) resistance exceeds range for accurate measurement

Ground noise voltage exceeds range for accurate measurement of resistance

Megger Voltage Clamp error

Megger Current Clamp error

TEST

N<->L Live and neutral connections reversed

Zref Reference loop measurement

R1+R2

ZMAX

NOTE: Some features detailed within this user guide are model dependent. Not all features appear on all models.

Instrument is running a test

Ground loop noise detected.

Loop measurement with Zref value automatically deducted

Loop maximum measurement

Instrument is too hot, allow to cool

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Introduction

Waste electrical and electronic equipment

WEEE

The crossed out wheeled bin placed on Megger products is a reminder not to dispose of the product at the

end of its life with general waste. Follow local regulations.

Megger is registered in the UK as a producer of electrical and electronic equipment. The registration number is WEE/HE0146QT

Battery and fuse location, ﬁtting and replacement

Battery type: 6 x 1.5 V Alkaline LR6 (AA) or NiMH HR6 rechargeable

Fuse type: 2 x F2 1000 V 30 kA fuses

Battery condition is shown by the following display symbols:

Where NiMH rechargeable batteries are ﬁtted, the battery condition display can be adjusted accordingly. Refer to “Setup options” on page 26 to change between alkaline and rechargeable batteries.

When set to NiMH batteries, the battery indicator in the display will show NiMH under the battery status symbol as below: (Feature available on all models).

NiMH

To replace batteries or fuse:

Switch off the instrument.

Disconnect the instrument from any electrical circuits.

Remove the battery cover from the base.

For battery replacement:

Remove old cells and reﬁt new batteries following correct polarity as marked on the battery holder.

Replace the battery cover.

Incorrect battery cell polarity can cause electrolyte leakage, resulting in damage to the instrument.

For fuse replacement

Withdraw each fuse in turn and check for failure. The blown fuse must be replaced with a F2 1000 V 30 kA fuse.

Rechargeable batteries and battery charging

Some models are supplied with rechargeable NiMH cells. These batteries can be charged in the instrument, using the supplied Megger charger.

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Introduction

To charge the batteries:

Ensure ﬁtted batteries are of the rechargeable NiMH type (as shown above).

Connect the 12 V dc plug of the charger to the socket on the front of the MFT marked

Warning:

• Whenever battery cells are being recharged, there should be no connections to the instrument terminals and the instrument should be switched off.

• Do not attempt to recharge non-rechargeable (Primary) cells. Doing so may result in instrument damage and may cause personal injury.

Ensure ambient temperatures are between 4º C and 40º C while charging the MFT.

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

Spent Alkaline and NiMH batteries are classiﬁed as portable batteries and should be disposed of in accordance with local regulations.

Megger is registered in the UK as a producer of batteries. The registration number is BPRN00142

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Operation

General operation – all models

Switching on

Turn the left hand rotary knob away from the off position.

The instrument will perform internal self tests then display the appropriate test screen, depending on the position of the function knobs.

Switching off

Turn the primary function (left hand rotary) knob to the OFF position.

The instrument will automatically turn itself off after 20 minutes* of inactivity. Press any button or turn either of the rotary knobs to turn back on.

* 2 minute option in Setup, refer to “Setup options” on page 26.

Backlight

Press the backlight button. The backlight will operate for 20 seconds.

Test buttons

The test buttons, or , are duplicated on the left and right of the unit. Both buttons perform the same function except, when the is displayed, in this case the right hand buttons perform a scrolling function. The

left RED button also performs bluetooth, storage and lock functions.

Test button lock

To lock the test button, hold down either of the RED test lock buttons with the L symbol, whilst holding down

the test button. If is displayed, the right hand buttons perform a scrolling function.

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