Manual Gossen Metrawatt METRAHIT 27EX (page 35 of 36) (English)

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Operating Instructions

METRA HIT27EX

Milliohmmeter for deployment

in potentially explosive atmospheres

3-349-336-49

7/2.15

2 GMC-I Messtechnik GMBH

1Display (LCD)

2ON|OFF key for ON / OFF

(ON short: instrument ON



ON short: background illumination ON



OFF short: background illumination OFF



OFF long: instrument OFF)

Operating mode menu: open submenus / acknowledge entries

3 DATA|CLEAR key for the functions save/delete measured value

Operating mode menu: Selection of individual menu items

against direction of flow,

 increase values

4 MAN|AUTO key for manual measuring range selection

Operating mode menu: Selection of individual menu items

in direction of flow

decrease values

5 MENU/ESC

Operating mode menu: Exit menu level and

return to a higher level,

exit parameters configuration

without saving data

6LED OK blinks: valid measured value

7LED ERROR blinks: incorrect connection

8 Connector jacks *

Measurement only on

voltage-free objects!

chapter 5

chapter 3

chapter 4

chapter 7.2

chapter 7.3

chapter 7

chapter 7.3

chapter 6

GMC-I Messtechnik GMBH 3

Symbols used in the Digital Display

1 Main display with decimal point

2 Auxiliary displays

3 : Milliohmmeter in continuous operation,

ON blinks at transmission frequency in transmission mode

4 REM: Memory mode operation, disappears after communication

via the interface is ended by means of key or switch

operation

5 ZERO: Zero balancing

6 MAN: Manual measuring range selection

7 Unit of measure (if blinking, refer to chapter 11 on page 33)

8 : Low battery voltage, replace batteries

* I- Measurement input

U- Sense – for 4-wire measurement

U+ Sense + for 4-wire measurement

I+ m;  measurement input

64 53

4 GMC-I Messtechnik GMBH

Contents Page

1 Application .............................................................. 5

2 Safety Features and Precautions ............................ 5

3 Initial Start-Up ......................................................... 8

4 Selecting Measuring Functions and Measuring Ranges .10

4.1 Automatic Measuring Range Selection ................................10

4.2 Manual Measuring Range Selection .................................... 10

4.3 Quick Measurements .........................................................10

5 Triple Digital Display ............................................. 11

6 Measured Value Storage ....................................... 12

6.1 Measured Value Storage – Key Function “DATA” .................12

7 Milliohm Measurement (4-Pole-Measurement) .... 14

7.1 Compensation of Cable Resistance ..................................... 14

7.1.1 Measurement with Kelvin Probe KC27 ................................ 14

7.2 Thermovoltage Compensation ............................................. 15

7.3 Milliohm Measurement with  100 mA DC [m] ................. 16

8 Using the Menus – from the Initial InFO Menu to

Operating and Measuring Parameters .................. 17

8.1 Sampling rAtE ........................................................ 17

8.2 Saving Measured Values .................................................... 18

8.2.1 Memory Mode – DATA Key Function (see also chapter 6.1) .. 18

8.2.2 Memory Mode Operation – STORE Menu Function ............... 19

8.3 Querying Memory Occupancy – INFO  MEMO/OCCUP ....... 19

8.4 Clearing the Memory – MEMO  CLEAr .............................20

8.5 Activating the Default Values ..............................................20

8.6 Transmission Mode Operation with RS 232 or USB Interface 21

9 Characteristic Values ........................................... 26

10 Maintenance ......................................................... 30

10.1 Batteries ............................................................................30

10.2 Fuses ................................................................................31

10.3 Housing and Display ........................................................... 32

10.4 Collection of Used Instruments and Environmentally

Compatible Disposal ........................................................... 33

11 System Messages ................................................. 33

12 Repair and Replacement Parts Service,

Calibration Center and Rental Instrument Service 34

13 Manufacturer’s Guarantee .................................... 35

14 Product Support .................................................... 35

15 Recalibration ......................................................... 36

GMC-I Messtechnik GMBH 5

1 Application

METRA HIT27EX is a milliohmmeter with 4-pole measure-

ment, which is designed for deployment in potentially

explosive environment.

In accordance with directive 94/9/CE dated 23th March

1994 the device is approved for being used in explosive,

gaseous atmospheres (IIA T4) with ambient temperatures

between –10 °C and +50 °C.

The device conforms to the following standards:

– EN 60079-0:2009 and EN 60079-0:2012

– EN 60079-11:2012

It bears CE certification number, type INERIS 05ATEX0040,

which has been conferred by the Ineris certification authority.

2 Safety Features and Precautions

You have selected an instrument which provides you with

high levels of safety.

This instrument fulfills the requirements of the applicable

European and national EC guidelines. We confirm this with

the CE marking. The relevant declaration of conformity can

be obtained from GMC-I Messtechnik GMBH.

The METRA HIT27EX is manufactured and tested in

accordance with safety regulations IEC 61010–1:2010 /

EN 61010–1:2010/VDE 0411–1:2011/EN 60079-0:2009

and

EN 60079-0:2012/EN 60079-11:2012. When used for its

intended purpose, safety of the operator, as well as that of

the instrument, is assured. Their safety is however not

guaranteed, if the instrument is used improperly or handled

carelessly.

In order to maintain flawless technical safety conditions, and to

assure safe use, it is imperative that you read the operating

instructions thoroughly and carefully before placing your instru-

ment into service, and that you follow all instructions contained

therein.

Use for Intended Purpose:

– The milliohmmeter described herein is a portable

instrument which can be held in one hand during mea-

surements.

– The milliohmmeter may only be operated with the

included or with type-tested batteries, as specified in

the Characteristic Values.

– The milliohmmeter may only be operated with closed

housing. The instrument must be removed from the

potentially explosive environment before opening the

housing to replace batteries or fuses.

– Only the type-tested fuses specified in the Characteris-

tic Values may be used.

– The milliohmmeter may only be used to perform such

measurements as described in chapter 7.

– The limits of the overload capacity may not be

exceeded. Refer to the “Characteristic Values” on

page 26 for overload values and overload duration.

6 GMC-I Messtechnik GMBH

– Measurements may only be performed within the indi-

cated ambient conditions. See page 29 for operating

temperature range and relative humidity.

– The instrument may not be used in a dusty atmo-

sphere.

– No maintenance operation may be performed in

potentially explosive atmospheres (cleaning, replace-

ment of batteries, opening the device, etc.)

Observe the following safety precautions:

• Type-tested Housing

The milliohmmeter may not be operated with open

housing.

In a potentially explosive atmosphere the housing may

not be opened. In this case, there is no protection

against explosions.

• Type-tested Batteries

Use the included or other type-tested batteries with

identical technical features only, see Characteristic Val-

ues.

Before use, please make sure that the housing cover is

closed. There is no protection against explosions when

the housing is open.

Batteries may only be replaced outside the potentially

explosive environment. No spare batteries may be

brought into the potentially explosive environment.

• Operation by qualified electricians

The instrument may only be operated by persons who

are capable of recognizing shock hazards and taking

the appropriate safety precautions. Shock hazards

exist anywhere, where voltages of greater than 33 V

(RMS) may occur.

• Shock Hazards

Avoid working alone when taking measurements

which involve shock hazards. Be certain that a second

person is present.

• Measurement Cables

Make sure that all measurement cables are in faultless

condition, e.g. undamaged insulation, no interruptions

in cables and plugs, etc.

• Unexpected Voltages

Be prepared for the occurrence of unexpected volt-

ages at devices under test (e.g. defective devices, after

inspecting the winding resistance of contactor relays,

etc.). For example, capacitors can still be dangerously

charged.

Perform measurements on voltage-free objects only.

• Type-tested Fuses (cannot be replaced by the user)

Only use type-tested fuses, as specified in the Charac-

eristic Values. There is no protection against explo-

sions when other fuses are used.

In order to prevent major damage to the instrument

when interference voltage is applied (within the admis-

sible limit values), the mmeasuring circuit is

equipped with a fuse F1 which makes these measur-

GMC-I Messtechnik GMBH 7

ing circuits highly resistive for the duration of the over-

load when high currents occur as a result of a distur-

bance. Another fuse F2 is located in the path between

batteries and instrument.

• Dusty Atmosphere

The instrument may not be used in a dusty atmosphere.

Meanings of symbols on the instrument:

Warning concerning a source of danger

(attention: observe documentation!)

Ground

Continuous, doubled or reinforced

insulation

Indicates EC conformity

Symbol for explosion protection:

Electrical equipment for intended use in

potentially explosive environments per

EN 60079-11

This device may not be disposed of with the

trash. Further information regarding the WEEE

mark can be accessed on the Internet at

www.gossenmetrawatt.com by entering the

search term ’WEEE’.

Repair, Parts Replacement and Balancing

When the instrument is opened, voltage conducting parts

may be exposed. The instrument must be disconnected

from the measuring circuit before the performance of

repairs, the replacement of parts, or balancing. If

balancing, maintenance or repair of a live open instrument

is required, this may only be carried out by trained

personnel who are familiar with the dangers involved.

Defects and Extraordinary Strains

If it may be assumed that the instrument can no longer be

operated safely, it must be removed from service and

secured against unintentional use. This applies particularly

for potentially explosive environments.

Safe operation can no longer be relied upon,

• If the instrument or the test probes are damaged

• If the instrument no longer functions

• If the limits of the overload capacity have been

exceeded, e.g. after the fuse has blown

• After long periods of storage under unfavorable condi-

tions (e.g. humidity, dust, or excessive temperature),

see „Ambient Conditions“ on page 29.

8 GMC-I Messtechnik GMBH

3Initial Start-Up

Insert Batteries

Warning!

Remove the instrument from the potentially explo-

sive environment before opening.

Only use the included type-tested batteries, as in-

dicated in the Characteristic Values.

Refer to chapter 10.1 regarding correct battery installation.

Note!

As a result of internal voltage monitoring, the instru-

ment may respond as follows if the battery voltage

level is low:

– Cannot be switched on

– Shuts back down immediately

– Shuts back down immediately when a load is

applied in the m range.

If this is the case, replace the batteries.

Warning!

Never replace the batteries in potentially explosive

atmospheres.

Switching the Instrument On Manually

➭ Press the ON|OFF key.

As long as the key is held depressed, all of the seg-

ments at the LCD are illuminated. The LCD is shown

on page 2. Power-up is acknowledged with a brief

acoustic signal.

The instrument is ready for use as soon as

the key is released.

Switching the Instrument On with a PC

After transmission of a data frame from the PC, the mil-

liohmmeter is switched on. See also chapter 8.6.

Switching the Instrument On Automatically

The milliohmmeter is switched on automatically in the

transmission and memory modes.

Note!

Electrical discharge and high frequency interference may cause

incorrect displays to appear, and may disable the measuring

sequence. In such cases, switch the instrument off and back on

again in order to reset. If the problem persists, briefly dislodge

the batteries from the connector contacts.

Setting Time and Date

See chapter 8 on page 17.

Switching the Instrument Off Manually

➭ Press the ON|OFF key until OFF is shown on the display.

GMC-I Messtechnik GMBH 9

Shutdown is acknowledged with two, brief acoustic sig-

nals.

Switching the Milliohmmeter Off Automatically – „SLEEP MODE“

The instrument is switched off automatically if none of the

keys are activated for approximately 10 minutes. Shut-

down is acknowledged with a brief acoustic signal.

Transmission mode: In this case, checking is first performed

to determine whether or not the sampling rate has been set

to a value of greater than 10 s. The instrument is switched

off after 10 minutes, but the instrument is reactivated 10 s

before data is to be saved to memory. The instrument is

then switched back off again.

In the transmission mode, the instrument can be manually

activated with the ON|OFF key. After activation of this type,

the instrument returns to the “SLEEP MODE”.

If the instrument is to be fully shut down, it must first be

activated and then switched off with the ON|OFF key. This

ends both memory mode and transmission mode

operation.

We recommend setting the instrument to continuous

operation for transmission mode operation.

The continuous operation mode is not effected by auto-

matic shutdown.

Disabling Automatic Shutdown

The instrument can be set to continuous operation.

➭ Press and hold the MENU/ESC key and then switch the

instrument on by pressing the ON|OFF key. Continuous

operation is indicated at the display with the symbol.

Switching LCD Illumination On and Off

➭ Briefly press the ON|OFF key after the instrument has al-

ready been switched on.

Illumination is switched off automatically after approxi-

mately 2 minutes.

Note: Electrical discharge and high frequency interference

may cause incorrect displays to appear, and may disable

the measuring sequence. In such cases, switch the instru-

ment off and back on again in order to reset.

If the problem persists,

1 leave the potentially explosive environment,

2 disconnect the instrument from the measuring circuit before open-

ing and refer to chapter 10.1 „Batteries“,

3 Briefly dislodge the batteries from the connector contacts.

10 GMC-I Messtechnik GMBH

4 Selecting Measuring Functions and Measuring

Ranges

4.1 Automatic Measuring Range Selection

The milliohmmeter is equipped with auto-ranging for all

measuring ranges. Auto-ranging is active as soon as the

instrument is switched on. The instrument automatically

selects the measuring range which allows for highest pos-

sible resolution for the applied quantity.

The instrument automatically switches to the next highest

or next lowest measuring range for the following measured

quantities:

4.2 Manual Measuring Range Selection

Auto-ranging can be deactivated and measuring ranges

can be selected manually in accordance with the following

table.

The manual mode is deactivated by pressing and holding

the MAN|AUTO key (approx. 1 s) or by switching the instru-

ment off and then back on again.

Note!

If the red ERROR LED lights up and OL is shown

on the display during manual measuring range

selection, you should switch to the next higher

range.

4.3 Quick Measurements

If you wish to perform quicker measurements than those

possible with the automatic measuring range selection

function, make sure to establish the appropriate measuring

range and to perform the following two functions:

•by manual measuring range selection, i. e. by selecting

the measuring range with the best resolution, see

chapter 4.2.

Measuring Ranges

Reso-

lution

Switching to next

highest range

at(... d + 1 d)

Switching to next

lowest range

at (... d –1 d)

300 m, 3 , 30  4 ¾ 31 000 2 800

30 m 3 ¾ 3 100 280



MAN|

AUTO

Function

Acknow-

ledgement

Dis-

play

Acoust.

Signal

short

Manual mode active:

utilized measuring range is fixed

MAN 1 x

short

Range switching sequence for:

m:30m 300 m3  30 30 m

MAN 1 x

long Return to automatic range selection

—

2 x

GMC-I Messtechnik GMBH 11

•via DATA function, see chapter 6.1. After the first mea-

surement, the proper measuring range will be auto-

matically determined so that measurements are per-

formed more rapidly from the second measured value

onwards.

With both functions, the established measuring range is

maintained for the subsequent series mode measurments.

5 Triple Digital Display

The three digital displays (1 main display and 2 auxiliary

displays) show the measured value with decimal and plus

or minus sign. The selected unit of measure is displayed as

well.

“0L” (overload) appears if the measuring range upper limit is

exceeded for the following measured quantities (the red

ERROR LED lights up simultaneously and openl appears

on the auxiliary display):

300 m, 3 , 30 : 30999

30 m: 3099

The digital display is refreshed at different frequencies for

the various measured quantities.

The main display appears immediately after the milliohm-

meter is switched on, but the auxiliary displays have to be

activated by pressing the DATA |CLEAR key.

In the following flowcharts, the initial displays are high-

lighted through the use of a bold border line.

023.00

022.00 data

m

Auxiliary Display Auxiliary Display

MAN

Main Display

12 GMC-I Messtechnik GMBH

6 Measured Value Storage

The METRA HIT27EX provides two entirely different

options for storing data:

• Measured Value Memory – DATA Key Function:

Each time the DATA key is pressed and a measuring

point is contacted, a measured value is stored (see

chapter 6.1).

• Memory Mode Operation – STORE Menu Function:

After activating the STORE menu function, all mea-

sured values are saved in accordance with the

selected sampling rate. Memory mode operation is

ended manually using the same menu function, see

chapter 8.2.

In both cases, saved measured values can be read out

with the help of METRAwin



10 PC software (as of version

5.22). However, read-out is only possible if a IR adapter

(BD232 or USB-HIT) has been plugged into the METRA

HIT27EX and connected to the PC with an interface cable

(see Data Interface page 29).

6.1 Measured Value Storage – Key Function “DATA”

Measured values can be automatically “frozen” with the

DATA hold function. This is useful when, for example, con-

tacting the measuring points with the test probes requires

your full attention.

Preparation of Measurement

Memory should be cleared before starting a measurement

series with the DATA key function.

This assures, on the one hand, that adequate memory

capacity is available and, on the other hand, that only data

from the last measurement series are read out in a contigu-

ous fashion. Check current memory occupancy to this

end: INFO MEMO/OCCUP

Clear memory if required: MEMO CLEAr.

Performing Measurements

➭ Press the DATA key.

The message data blinks and indicates readiness for

acquiring the first measured value.

➭ Contact the measuring point as described in chapter

7.3.

After applying the test probes to the measuring point:

– the green LED OK indicates: safe measurement connection.

– The initially acquired value is transferred to the main

display where it remains stored. This is acknowledged

by two successive acoustic signals.

„MAN“ (and, additionally, „ZERO“ in the M measuring

ranges) is displayed simultaneously and indicates that

the measuring range is now fixed.

– the momentary measured values continue to be

shown in the auxiliary display on the left.

➭ Lift the test probes from the measuring point.

The message openl appears on the auxiliary display.

GMC-I Messtechnik GMBH 13

The red LED ERROR lights up as long as no contact has

been established between the test probes and the mea-

suring point. The green LED OK continues to light up when

a valid measured value has already been stored.

Prior to contacting the next measuring point, the function

DATA must be activated once more by pressing the DATA

key. The message data blinks and indicates readiness for

acquiring the next measured value.

As long as the DATA function is active and all measure-

ments are within the measuring range which has been

Acoustic signal 1x

0.L

openl



0.L

0.ldata



DATA

044.66

044.59 data

m

MAN

Acoustic signal 2x

Meas. Contact

044.66

openl data

m

MAN

Acoustic signal 2x

Disconnect contact

Acoustic signal 1x

DATA

044.66

openl data

m

MAN

blinks

ERROR OK

ERROR

ZERO

14 GMC-I Messtechnik GMBH

automatically adjusted, the measuring ranges should not

be changed manually.

The DATA function is deactivated if the DATA | CLEAR key is

pressed and held (approx. 1 s) or by switching the instru-

ment off and back on again.

7 Milliohm Measurement (4-Pole-Measurement)

7.1 Compensation of Cable Resistance

Electrical resistance is a dipole quantity which can

generally only be measured using two poles. This is

accomplished by directing a measuring current of

predetermined magnitude through the device under test,

and measuring the resultant voltage drop. The respective

resistance value is derived from the quotient of these two

values.

The two points between which voltage is measured are

decisive as regards the results of the measurement. All

resistances between these two points add to the

measured resistance value. These include contact

resistance, as well as cable resistance. If a very low

resistance value needs to be measured, for example

contact resistance at a contactor with a value of only a few

milliohms, the points between which voltage is measured

must be moved out of the measuring instrument and

positioned as closely as possible to the device under test.

For this reason, the measuring instrument is equipped with

separate jacks for current feed and voltage measurement.

This type of 4-pole connection is known as connection

according to Kelvin.

KC4 Kelvin clips and KC27 Kelvin probes (available as

accessories) allow for easy, correct connection.

7.1.1 Measurement with Kelvin Probe KC27

m

U+U–

I+

red

black

Milliohm measurement on

conductor bars, welds,

coils, etc. with Kelvin probe

KC27 and Kelvin clip KC4

Direct the spring-loaded test

probe inward towards the DUT,

if possible, as it is connected

via the red plug with U

or U

–

(Sense) .

I–

GMC-I Messtechnik GMBH 15

7.2 Thermovoltage Compensation

Thermovoltages which occur as a result of material and

temperature differences may distort measurement results.

For this reason, the instrument is equipped with automatic

thermovoltage compensation in the relevant measuring

ranges.

After switching on the milliohmmeter, „termoc“ is displayed,

indicating that an automatic thermovoltage compensation

for the 30 mand 300 mmeasuring ranges will be per-

formed in the background for all future measurements.

ZERO signals that the value of the thermovoltage has

already been taken into account for the indicated measu-

ring result.

After the first measurement – lift the test probe from the

measuring point – „termoc“ disappears to facilitate the rea-

ding of the measured values. The automatic thermovoltage

compansation remains activated.

000.10

termoC

m



Measure

thermo-

voltage

Relevant measuring ranges:

30 mund 300 m

I < 100 mA

ZERO

16 GMC-I Messtechnik GMBH

7.3 Milliohm Measurement with  100 mA DC [m]

➭ Make sure that the device under test is voltage-free.

➭ Connect the device under test as shown.

KC4 Kelvin clips and KC27 Kelvin probes (available as

accessories) allow for easy, correct connection.

Resistance at the current jacks should amount to <1.

➭ If applicable, select the desired measuring range using

the MAN|AUTO key: 30 m, 300 m, 3  or 30 .

➭ Contact the measuring point.

The green LED OK must light up.

Note!

If the measuring current is interrupted during

4-wire-m-measurement or if the fuse F1 is defec-

tive, the message „open L“ flashes on the display

and the red LED ERROR lights up.

If fuse is defective, see chapter 10.2.

m

U+U–

Voltage Drop Measuring Current

m: 0.01 m  30 

Overall Measuring Range:

+–

Measurement Cables,

KC27 or KC4

Note:

When using KC27 or

KC4 always set red

probe plug at U

–

, respectively.

I+

I–

GMC-I Messtechnik GMBH 17

8 Using the Menus – from the Initial InFO Menu to

Operating and Measuring Parameters

Menu-driven operation via the initial „1NF0 “ menu allows

the user to query online help, activate the memory and

query memory occupancy, activate the interface and

configure device parameters.

➭ The initial „1NF0 “ menu is accessed by simultaneously

pressing and holding the MENU/ESC and ON|OFF keys

with the instrument switched on, until „1NF0 “ appears

at the display.

➭ The display can be switched from the main „1NF0 “

menu to the other main menus including “store“,

“memo”, “ send” and “set”, and then back to the „1NF0 “

menu, by repeatedly pressing the  keys.

➭ After accessing the desired main menu, the associated

submenus are opened by activating the  key.

➭ The desired parameter or the desired function is se-

lected by repeatedly pressing the  keys.

➭ Acknowledge with the  key in order to change the

corresponding parameter or parameters.

➭ After the desired digit has been selected with the 

keys and the value has been adjusted with the 

keys, the next digit is accessed with the  key, or the

display is returned to the start menu or switched to the

next submenu.

➭ The measuring mode is started by repeatedly pressing

the MENU/ESC key until the measuring display appears.

➭ The milliohmmeter is switched off by pressing and

holding the ON|OFF key until the display goes blank.

The following pages include an overview of the menu

structure.

8.1 Sampling rAtE

The sampling rate specifies the time interval after which the

respective measured value is transmitted to the interface or

to measured value memory. See page 24 for possible set-

tings. The lower limit of the sampling rate which cannot be

fallen short of, is 0.5 s.

18 GMC-I Messtechnik GMBH

8.2 Saving Measured Values

The METRA HIT27EX provides two entirely different

options for storing data:

• Messwertspeicherung – Tastenfunktion DATA:

Measured Value Memory – DATA Key Function:

Each time a measuring point is contacted, a measured

value is stored in accordance with a defined condition

(see chapter 6.1 and chapter 8.2.1).

• Memory Mode Operation – STORE Menu Function:

After activating the STORE menu function, all mea-

sured values are saved in accordance with the

selected sampling rate. Memory mode operation is

ended manually using the same menu function.

In both cases, saved measured values can be read out

with the help of METRAwin



10 PC software (as of version

5.22). However, read-out is only possible if a BD232 IR

adapter has been plugged into the METRA HIT27EX and

connected to the PC with an interface cable.

8.2.1 Memory Mode – DATA Key Function (see also chapter 6.1)

The instrument is equipped with a measured value

memory (32 kB) which is synchronized with a quartz

movement, and has an average capacity of 1000

measured values. Minimum capacity is 800 measured

values and maximum capacity is 1200 measured values.

Data are stored and can be transmitted directly to a PC

with the METRAwin



10 software. Date and time must be

reset if the batteries are depleted and/or replaced.

Measured values are stored in so-called blocks. Measured

values resulting from the same measuring function are

saved to the same block.

Only absolute values and absolute time stamps can be

saved, i.e. no relative or  values, and no relative time

stamps.

Memory content can only be read out with the help of a

PC, an IR adapter (BD232), and METRAwin



10 analysis

software.

Stored measurement data blocks are retained even if the

instrument is without voltage supply.

Vorbereitungen für den Speicherbetrieb

Preparing for Memory Mode Operation

➭ First set the sampling rate for memory mode operation,

and then start memory mode operation.

The sampling rate can also be changed during mem-

ory mode operation.

➭ First select the desired measuring function and an ap-

propriate measuring range.

➭ Check the battery voltage level before starting long-

term measurement recordings (see chapter 10.1 on

page 30).

GMC-I Messtechnik GMBH 19

8.2.2 Memory Mode Operation – STORE Menu Function

➭ First set the sampling rate for memory mode operation,

and then start memory mode operation.

The sampling rate can also be changed during mem-

ory mode operation.

➭ First select the desired measuring function and an ap-

propriate measuring range.

➭ Check the battery voltage level before starting long-

term measurement recordings, see chapter 10.1 on

page 30.

Starting Memory Mode Operation with Menu Functions

➭ Open the “Operating Mode” menu (refer to the menu

diagram) and select the StorE function.

➭ Now activate the  key to open the start menu for

memory mode operation: StArt blinks.

Activate the key once again in order to start memory

mode operation: REM appears at the display.

➭ Press the  key in order to switch to the measuring

function.

The “SLEEP MODE” is still active, i.e. the device is

switched on and off automatically at sampling rates of long

duration (see chapter 3).

When memory capacity has been exhausted, MEMO FULL

appears at the display, and an acoustic signal is generated

simultaneously. The signal can be deactivated by pressing

any key.

REM Display

The REM symbol indicates that memory mode operation

has been activated via menu function STORE.

Press the  key if you wish to monitor the measured val-

ues also during the memory process.

The „STORE“ function cannot be started while the „DATA“

function is activated.

Exiting Memory Mode Operation with Menu Functions

➭ Select the StorE menu.

➭ Activate the  key: StOP blinks.

➭ Activate the  key once again: the auxiliary displays

are cleared. Memory mode operation has now been

deactivated.

➭ Press the  key in order to return to the measuring

function.

➭ Memory mode operation can also be exited by switch-

ing the instrument off.

8.3 Querying Memory Occupancy – INFO MEMO/OCCUP

Memory occupancy can be queried from the „1NF0 “ menu.

The main display shows current occupancy as a percent-

age between 001 and 100%.

20 GMC-I Messtechnik GMBH

8.4 Clearing the Memory – MEMO CLEAr

Attention!

This function deletes all measured values from

memory.

This function cannot be performed during memory mode;

bUSY

MEMO

is displayed instead of CLEAR.

8.5 Activating the Default Values

Previously entered changes can be undone, and the

default settings can be reactivated. This may be advisable

after the occurrence of software or hardware errors.

➭ Simultaneously press and hold the MENU/ESC, MAN|AUTO

and DATA | CLEAR keys, and switch the instrument on

with the ON|OFFkey.

GMC-I Messtechnik GMBH 21

8.6 Transmission Mode Operation with RS 232 or USB Interface

The METRA HIT27EX is equipped with an bidirectional

infrared interface for the transmission of measurement data

to a PC. Data are transferred optically through the

instrument housing by means of infrared light to an

interface adapter (accessory BD232 or USB-HIT), which is

attached to the instrument. The adapter’s RS 232 or USB

interface allows for the establishment of a connection to

the PC via an interface cable. Beyond this, commands and

parameters can be transmitted from the PC to the

instrument as well. The following functions can be

executed:

• Configuration and read-out of measuring parameters

• Measuring function and measuring range selection

• Start measurements

• Read out measured values.

Activating the Interface

The interface is switched on manually as described below

for transmission mode operation. The instrument

continuously transmits measurement data to the PC via the

interface adapter in this operating mode. The interface is

activated automatically by the PC for receiving operation

(i.e. the instrument receives data from the PC).

Starting Transmission with Menu Functions

InFO  SEnd StArt 

The symbol blinks at the display in order to indicate

interface operation.

Automatic Activation and Deactivation of the Transmission Mode

If the sampling rate is 20 s or longer, the display is

switched off automatically between samples in order to

prolong battery service life.

Exception: continuous operation

As soon as an event occurs, the display is automatically

switched back on.

Configuring Interface Parameters

Addr – Address

If several milliohmmeters are connected to the PC via inter-

face adapters, an unique address must be assigned to

each device. Address 1 should be used for the first device,

address 2 for the second etc. If only one milliohmmeter is

utilized, an address between 1 and 14 should be used.

Address 15 is not used for addressing, i.e. the device with

address 15 always responds, regardless of the actual

address.

22 GMC-I Messtechnik GMBH

Main Menus and Submenus

1nf0

mem0



send

Set

MENU/ESC



Clear

yes no





send

0ff/0n start/st0p





Current

Status

3.9

batt

8 01

mem0 oCCUp

set

rate







Battery

Voltage Level



 

Memory Occupancy

(see chapter 8.3)

store store

0ff/0n start/st0p







ESC

GMC-I Messtechnik GMBH 23



Selection must blink:

YES: delete memory

no: do not delete



Acknowledge

selection



StArt blinks

Activate:

Transmission mode



StOP blinks

Activate:

no Transmission mode

t im e

12:58 :08

d a t e

15 08 .02



Current Time Current Date



Delete Memory Menu (see

chapter 8.4)

Transmission Mode (see chapter 8.6)

Configure Device Parameters (see chapter 8.1)

Query Information

t C a l

15 08 .02

Calibration Date

t a d J

15 08 .02

Balancing Date

blinks

does not blink

Display „EMPTY “: Memory is empty

 

Memory Mode Menu



StArt blinks

Activate:

Memory mode active



StOP blinks

Activate:

Memory mode inactive

REM is displayed REM disappears

During memory

mode the memory

cannot be deleted,

bUSY

MEMO

is dis-

played instead of

CLEAr.



active

See next page for

more submenus

24 GMC-I Messtechnik GMBH

SEt Submenu for rAtE, Addr, dAtE and tIME Parameters

set

rate

set

addr



set

tIme

set

00:10 :00 rate





set

15 addr





set

13:15:21 t Ime





set

13.08.02 date

Continued from previous page

set

date







ESC

GMC-I Messtechnik GMBH 25



Change

Value



Acknowledge

Sampling Rate

00:00:01, 00:00:02, 00:00:05, 00:00:10, 00:00:20, 00:01:00

00:02:00, 00:05:00, 00:10:00, 00:20:00, 01:00:00; 0.50 = 500 ms

Possible Settings



Change

Value

Set Device Address



Acknowledge

Address



Change

Value

Set Time



Acknowledge

Selection

Set Date



Select

Position



Change

Value



Acknowledge

Selection



Select

Position

Possible Settings

Digits

blinks

Possible Settings (see also chapter 8.6): 0  15

Set Sampling Rate (see also chapter 8.1)

(hh:mm:ss, h = hours, m = minutes, s = seconds)

(hh:mm:ss, hh=hours, mm=minutes, ss=seconds)

(TT:MM:JJ, TT=day, MM=month, JJ=year)

26 GMC-I Messtechnik GMBH

9 Characteristic Values

Display:

4¾ places in the range of 300 m, 3 , 30 ,

3¾ places in the range of 30 m,

A different sampling rate can be selected in the rAtE menu for saving and

transmitting measured values.

at 0 +40C

In the event of an overload (connections I+, I–), the integrated 500 mA/600V

fuse is triggered.

applies as from 10% of the measuring range

EX parameters: Vo = 6 V, Co = 559 μF, Io = 576 mA,

Lo = 300 μH, Po = 0,785 W

Key

rdg. = measured value, d = digit, 4 L = 4-wire measurement

Influencing Quantities and Influence Error

With zero balancing

Real-Time Clock

Accuracy 1min/month

Temperature Influence 50 ppm/K

Reference Conditions

Ambient temperature +23 C 2K

Relative humidity 40 ... 60%

Battery voltage 5.0 V 0.1 V

Measuring

Function

Measuring

Range

Resolution at Upper

Range Limit

4¾ 30000 / 3¾ 3000

Open-circuit

voltage approx.

Meas. cur-

rent approx.

m

(4 L)

30 m 0.01 m

4  6 V

100 mA

300 m 0.01 m 100 mA

3  0.1 m 10 mA

30  1m 10 mA

Measuring

Function

Intrinsic Error at Max. Resolution

under Reference Conditions

Overload Capacity

(...% rdg. + ... d) Value Time

m

(4 L)

30 m 2 + 20

0.6 V

cont.

300 m 1 + 20

3  1 + 10

30  1 + 10

Influencing

Quantity

Sphere of

Influence

Measuring Range

Influence Error

 (... % rdg. + d)/10 K

Temperature

0  +21 C

and

+25+40 C

m,  1 + 10

Influencing

Quantity

Sphere of

Influence

Measuring Range

Influence Error

Relative

humidity

90 %

3 days

instrument off

All measured

quantities

1 x intrinsic error

GMC-I Messtechnik GMBH 27

Response Time

Response time (after manual range selection)

* without parallel capacity

Display Elements

LCD panel (65 mm x 30 mm) with triple 7 segment display

(measured values), units of measure and various special

functions.

Display / Char. Height 7-segment characters

Main display: 12 mm

Auxiliary displays: 7 mm

Number of places 4¾ places 30999 steps

Overflow display „0. L“ appears

LCD test All display segments available

during operation are briefly acti-

vated after the instrument is

switched on

Background illumination can be activated or deactivated

LED OK (green) lights up when contacting of

measuring point is OK

LED ERROR (red) lights up when measuring cur-

rent is interrupted (invalid measu-

rement, poor contact, when „0. L“

is displayed)

Power Supply

Batteries 4 x 1,5 V PhilipsLonglife R6L4B

LR6 (AA-Size)

Service life

* 1 measuring cycle = 5 s

Additional consumption for:

Interface operation: 0.5 mA

LCD illumination: 40 mA at 6 V.

Battery test Range m@100mA:

“ ” is displayed automatically if

battery voltage drops below

approx. 4.6 V.

The instrument is switched off if

battery voltage drops to below

approx. 4.3 V.

Fuses

Fusible link F1 for all

m/measuring ranges 500 mA/600 V AC;

breaking capacity 60 A at

600 V AC

For batteries F2 250 mA/125 V AC EX

Measuring Range

Response Time

for Digital Display

Measured Quantity

Step Function

m,  1.5 s

from  to 50%

of upper range limit value

Measuring Function Number of Measurements *

m@100mA > 500

@10mA > 800

28 GMC-I Messtechnik GMBH

Electrical Safety

Safety class II per IEC/EN 61010-1:2010

/VDE 0411-1:2011

Measurement category 50 V CAT I

Contamination degree 2

EX marking CE 0080

II 2 G Ex ia IIA T4 Gb

Ex = prototype tested

II = Device group

2 = Device category

G = Atmosphere (gas)

Ex = conforms to European

Ex standards

ia = Type of protection

(intrinsic safety)

IIA = Explosion category

T4 = Temperature class

Gb = Equipment Protection

Level (EPL)

Tam b. = – 10 C ... +50 C

(Tamb. = ambient temperature)

Prototype test certificate

INERIS 05ATEX0040

INERIS = Inspection and Certifi-

cation Authority

05 = Year

ATEX = Guideline

(Atmospheres Explosives)

0040 = Test Report No.

Serial number (fabrication number)

X Y 123456 X = year of manufacture:

P=2005, Q=2006, R=2007, ...

Y = month of manufacture

January A

February B

March C

April D

May E

June F

July G

August H

September I

October J

November K

December L

123456 = serial number

PG123456 means for example = device was built in July 2005

GMC-I Messtechnik GMBH 29

Serial plate

GOSSEN METRAWATT manufacturer

Thomas-Mann-Str. 16-20

street

D-90471 Nürnberg post code / place

METRA HIT 27EX designation of device

INERIS 05ATEX0040

prototype test certificate see above

X Y 123456 serial number see above

II 2 G EX marking see above

EX ia IIA T4 Gb EX marking see above

Tam b.= –10



C ... +50



ambient temperature

Electromagnetic Compatibility (EMC)

Interference emission

Interference immunity EN 61326-1:2006 Tab A1

Data Interface

Data transmission bidirectional, optical via infrared

light through the housing (read

data and configure parameters)

With interface adapter as accessory

BD232 IR to RS232C, serial,

per DIN 19241, cascadable for

multi-channel operation

USB-HIT IR to USB 1.1/USB 2.0,

single-channel operation

baud rate (MM  PC) 9600 baud

Ambient Conditions

Accuracy range 0 C ... +40 C

Operating temperatures 10 C ... +50 C

Storage temperatures 25 C ... +70 C (w/o batteries)

Relative humidity 45% ... 90%,

no condensation allowed

Elevation up to 2000 m

Mechanical Design

Protection IP 54

Extract from table on the meaning of IP codes

Dimensions 84 mm x 195 mm x 35 mm

Weight approx. 380 g with batteries

(without GH18 protective rubber

cover)

IP XY

(

digit X)

Protection against

foreign object entry

IP XY

digit Y)

Protection against the

penetration of water

5 dust protected 4 splashing water

30 GMC-I Messtechnik GMBH

10 Maintenance

10.1 Batteries

Warning!

Ex Environment: Remove the instrument from the

potentially explosive environment before opening.

Attention!

Non-Ex Environment: Disconnect the instrument

from the measuring circuit before opening to re-

place batteries!

Removing the Batteries During Periods of Non-Use

The integrated quartz clock draws power from the batter-

ies, even when the instrument is switched off. It is advis-

able to remove the batteries during long periods of non-

use for this reason (e.g. vacation). This prevents excessive

depletion of the batteries, which may result in damage

under unfavorable conditions.

Checking Battery Voltage-Level and Condition

The current battery voltage level can be queried in the

“Info” menu (see chapter 8 on page 17):

MENU/ESC + ON|OFF  InF0 X.X V (bAtt).

Make sure that no battery leakage has occurred before ini-

tial start-up, and after long periods of storage. Continue to

inspect the batteries for leakage at short, regular intervals.

– If battery leakage has occurred, carefully and completely

clean electrolyte from the instrument with a damp

cloth, and replace the batteries before using the instru-

ment.

– If the “ ” symbol appears at the display, the batteries

should be replaced as soon as possible. You can con-

tinue working with the instrument, but reduced mea-

suring accuracy may result.

GMC-I Messtechnik GMBH 31

Replacing the Batteries

Warning!

Use the included type-tested batteries only, as de-

scribed in the Characteristic Values.

➭ Set the instrument face down onto a flat working sur-

face, loosen the two screws at the back and lift off the

housing base, starting at the bottom. The housing top

and housing base are held together with the help of

snap hooks at the top front.

➭ Remove the batteries from the battery compartment.

➭ Insert four 1.5 V batteries into the battery compart-

ment, making sure that the plus and minus poles

match up with the provided polarity symbols.

➭

Important for reassembly: First set the housing base

onto the housing top and align accurately (see photo

below). Then press the two housing halves together,

first at the bottom front (a), and then at the top front (b).

➭ Secure the housing base with the two screws.

Warning!

The instrument may not be operated if the housing

base has not been properly installed and secured!

Disposing of Batteries

Dispose of old batteries properly, i.e. at a designated col-

lection point.

10.2 Fuses

Inspecting the Integrated Fuse F1

The fuse F1 is located at the measuring input. When the

fuse is defective, the measurements in the m/ ranges

are faulty.

➭ Short circuit the two outer „I–“ and „I+“ jacks.

Display < 0.4 : fuse OK.

Display „0L“ and „openL“:fuse blown.

Attention!

If a fuse should blow, eliminate the cause of over-

load before placing the instrument back into ser-

vice!

(b) (a)

32 GMC-I Messtechnik GMBH

Inspecting the Integrated Fuse F2

The fuse F2 is located in the battery supply path. If the LC

display is not active upon switching the instrument on:

➭ check whether the batteries have been inserted with

the polarity symbols at the correct end.

If the LCD remains inactive it might be defective.

Replacing the Fuses

Fuse F1 for the m/measuring ranges and fuse F2 for

the battery power supply are both firmly soldered in. They

are not intended to be replaced by the user.

If one of the fuses is defective, you are requested to send

the instrument to our repair service or to the respective

subsidiary abroad (the address is given in chapter 12).

This provides you with the guarantee that type-tested and/or

Ex-approved fuses with the correct triggering characteristics,

nominal current and breaking capacity are inserted. Addition-

ally, the instrument will be subjected to a safety test.

Instructions for the service

Warning!

Ex Environment: Remove the instrument from the

potentially explosive environment before opening.

Attention!

Non-Ex Environment: Disconnect the instrument

from the measuring circuit before opening to re-

place batteries!

➭ Open the instrument in the same manner as for replac-

ing the batteries.

Warning!

Use the specified type-tested fuses only!

If fuses with other blowing characteristics, other

current ratings or other breaking capacities are

used, the operator is placed in danger, and pro-

tective diodes, resistors and other components

may be damaged.

The use of repaired fuses and short-circuiting the

fuse holder are prohibited.

10.3 Housing and Display

No special maintenance is required for the housing. Keep out-

side surfaces clean. Use a cloth slightly dampened with water

for cleaning.

Attention ! Do not under any circumstances use cleansers, abrasi-

ves and solvents !

This particularly applies to the display surface to avoid

damaging the high-quality explosion protection coating,

thus reducing its efficiency.

GMC-I Messtechnik GMBH 33

10.4 Collection of Used Instruments and Environmentally

Compatible Disposal

The milliohmmeter is a category 9 product (monitoring and

control instrument) in accordance with ElektroG (German

Electrical and Electronic Device Law). This device is sub-

ject to the RoHS Directive. Further-more, we make refer-

ence to the fact that the current status in this regard can

be accessed on the Internet at www.gossenmetra-

watt.com by entering the search term WEEE.

We identify our electrical and electronic devices in

accordance with WEEE 2012/19EU and ElektroG

with the symbol shown to the right per DIN EN

50419. These devices may not be disposed with

the trash. Please contact our service department regarding

the return of old devices. (see chapter 12).

If you use type-tested batteries in your instrument or acces-

sories which no longer function properly, they must be duly

disposed of in compliance with the applicable national reg-

ulations.

Batteries or rechargeable batteries may contain harmful

substances or heavy metal such as lead (PB), cadmium

(CD) or mercury (Hg).

They symbol shown to the right indicates that

batteries or rechargeable batteries may not be

disposed of with the trash, but must be delivered

to collection points specially provided for this

purpose.

11 System Messages

The following messages appear at the main display, or the

auxiliary displays as required. See “Symbols used in the

Digital Display” on page 3 for messages displayed at visible

segments.

Blinking Unit of Measure

All measuring functions are balanced for each METRA

HIT27EX at the factory in accordance with the respective

technical specification. If a unit of measure blinks, this indi-

cates that balancing constants which have been estab-

lished and saved to the milliohmmeter are no longer avail-

able for the respective function. If this is the case, mea-

surement results may deviate from the specification. We

recommend sending the instrument to our Repair and

Replacement Parts department for rebalancing (see chap-

ter 12).

Message Function Meaning

0. L Measuring Indicates overflow

open

4-wire-m

Measuring current interrupted or fuse defective.

Pb Cd Hg

34 GMC-I Messtechnik GMBH

12 Repair and Replacement Parts Service,

Calibration Center* and Rental Instrument Service

If required please contact:

GMC-I Service GmbH

Service Center

Thomas-Mann-Straße 20

90471 Nürnberg • Germany

Phone +49 911 817718-0

Fax +49 911 817718-253

E-Mail service@gossenmetrawatt.com

www.gmci-service.com

This address is only valid in Germany.

Please contact our representatives or subsidiaries for ser-

vice in other countries.

French subsidiary:

GMC Instruments France SAS

3, rue René Cassin

F-91349 Massy Cedex

Phone +33 1 69 20 89 49

Fax +33 1 69 20 54 92

E-mail info@gmc-instruments.fr

* DAkkS Calibration Laboratory for Electrical Quantities

D-K-15080-01-01 accredited as per DIN EN ISO/IEC

17025:2005

Accredited quantities: direct voltage, DC value, DC resistance,

alternating voltage, AC value, AC active power, AC apparent

power, DC power, capacitance, frequency and temperature

Competent Partner

GMC-I Messtechnik GMBH is certified per

DIN EN ISO 9001:2008.

Our DAkkS Calibration Laboratory has been accredited in

accordance with DIN EN ISO/IEC 17025:2005 by the

Deutsche Kalibrierdienst (German Calibration Service)

under registration number D-K-15080-01-01.

Our competence in the field of metrology covers test

reports, Proprietary Calibration Certificates as well as DAkkS

Calibration Certificates.

Our range of services is complemented by our Test Equip-

ment Management service which is provided free of charge.

An on-site DAkkS calibration station is an integral part of our

service department. If any faults are detected during cali-

bration, our specialists are able to carry out the necessary

repairs with original replacement parts.

Needless to say, in our function as calibration laboratory,

we calibrate all instruments, irrespective of the manufac-

turer.

GMC-I Messtechnik GMBH 35

13 Manufacturer’s Guarantee

The guarantee period for all METRA HIT digital multimeters

and calibration instruments is 3 years after date of ship-

ment.

The guarantee covers materials and workmanship. Dam-

age resulting from use for any other than the intended pur-

pose or operating errors, as well as any and all consequen-

tial damage, is excluded.

The calibration certificate confirms that the product con-

formed to the specified technical data at the time of cali-

bration. We guarantee the observance of the specified

technical data within the admissible tolerance limits for a

period of 12 months from delivery.

14 Product Support

If required please contact:

GMC-I Messtechnik GMBH

Product Support Hotline

Phone +49 911 8602-0

Fax +49 911 8602-709

E-Mail support@gossenmetrawatt.com

French subsidiary:

GMC Instruments France SAS

3, rue René Cassin

F-91349 Massy Cedex

Phone +33 1 69 20 89 49

Fax +33 1 69 20 54 92

E-mail info@gmc-instruments.fr

GMC-I Messtechnik GMBH

Südwestpark 15

90449 Nürnberg • Germany

Phone+49 911 8602-111

Fax +49 911 8602-777

E-Mail info@gossenmetrawatt.com

www.gossenmetrawatt.com

Edited in Germany • Subject to change without notice

15 Recalibration

The respective measuring task and the stress to which

your measuring instrument is subjected affect the ageing of

the components and may result in deviations from the

guaranteed accuracy.

If high measuring accuracy is required and the instrument

is frequently used in field applications, combined with

transport stress and great temperature fluctuations, we

recommend a relatively short calibration interval of 1 year. If

your measuring instrument is mainly used in the laboratory

and indoors without being exposed to any major climatic

or mechanical stress, a calibration interval of 2-3 years is

usually sufficient.

During recalibration* in an accredited calibration laboratory

(DIN EN ISO/IEC 17025) the deviations of your instrument

in relation to traceable standards are measured and docu-

mented. The deviations determined in the process are

used for correction of the readings during subsequent

application.

We are pleased to perform DAkkS or factory calibrations

for you in our calibration laboratory. Please visit our website

www.gossenmetrawatt.com ( Company  DAkkS Cali-

bration Center or  FAQs  Calibration questions and

answers).

By having your measuring instrument calibrated regularly,

you fulfill the requirements of a quality management system

per DIN EN ISO 9001.

* Verification of specifications or adjustment services are not part of the cali-

bration. For products from our factory, however, any necessary adjustment

is frequently performed and the observance of the relevant specification is

confirmed.

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