METREL TeraOhmLT 10kV User manual

TeraOhmLT 10kV
MI 3209
Instruction manual
Version 1.1.1; Code No. 20 753 234

2
Distributor:
Manufacturer:
METREL d.d.
Ljubljanska cesta 77
1354 Horjul
Slovenia
web site: http://www.metrel.si
e-mail: [email protected]
Mark on your equipment certifies that it meets requirements of all subjected EU regulations
Hereby, Metrel d.d. declares that the MI 3209 is in compliance with subjected EU
directives. The full text of the EU declaration of conformity is available at the
following internet address https://www.metrel.si/DoC.
© 2013 - 2021 METREL
No part of this publication may be reproduced or utilized in any form or by any means
without permission in writing from METREL.

MI 3209 TeraOhmLT 10kV Table of contents
3
Table of contents
1General Description............................................................................................5
Features........................................................................................................5
2Safety and operational considerations .............................................................6
Warnings and notes......................................................................................6
Battery and charging of Lead –Acid battery.................................................8
2.2.1 Precharge..............................................................................................9
Standards applied.......................................................................................11
3Instrument description .....................................................................................12
Instrument casing .......................................................................................12
Operator’s panel .........................................................................................12
Accessories ................................................................................................14
3.3.1 Test leads............................................................................................14
Display organization ...................................................................................16
3.4.1 Measurement result window................................................................16
3.4.2 Measurement control window..............................................................17
3.4.3 Message window.................................................................................18
3.4.4 Battery, time and communication indication ........................................19
3.4.5 Measurement result line ......................................................................20
3.4.6 Graphical presentation of measured data............................................20
3.4.7 Backlight operation..............................................................................20
4Main menu .........................................................................................................21
Instrument Main menu................................................................................21
Memory menu.............................................................................................22
4.2.1 Saving results......................................................................................22
4.2.2 Recalling results ..................................................................................23
4.2.3 Deleting results....................................................................................24
4.2.4 Clearing complete memory content.....................................................24
Settings menu.............................................................................................25
4.3.1 Language selection..............................................................................26
4.3.2 Initial Settings selection.......................................................................26
4.3.3 Time selection .....................................................................................26
4.3.4 Date selection......................................................................................26
4.3.5 Transfer mode .....................................................................................27
4.3.6 Contrast selection................................................................................27
4.3.7 Warning sound ....................................................................................27
4.3.8 Graph selection....................................................................................27
4.3.9 Break Down selection..........................................................................28
4.3.10 Instrument info.....................................................................................28
Help Menu ..................................................................................................28
5Measurements...................................................................................................29
General information about high voltage testing...........................................29
5.1.1 The purpose of insulation tests............................................................29
5.1.2 DC vs. AC testing voltage....................................................................29
5.1.3 Typical insulation tests.........................................................................29
5.1.4 Electrical representation of insulating material ....................................29
Some application examples........................................................................30
5.2.1 Basic Insulation resistance test ...........................................................30

MI 3209 TeraOhmLT 10kV Table of contents
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5.2.2 Voltage dependence test –Step Voltage Test.....................................30
5.2.3 Time dependence test –Diagnostic Test.............................................31
5.2.4 Withstanding Voltage Test...................................................................32
Guard terminal............................................................................................33
Averaging options.......................................................................................34
5.4.1 The purpose of averaging....................................................................34
5.4.2 Example of averaging..........................................................................35
Measurement menu....................................................................................36
Insulation Resistance Measurement...........................................................37
5.6.1 Set Limit...............................................................................................39
Diagnostic test............................................................................................40
5.7.1 Dielectric Absorption Ratio (DAR)........................................................42
5.7.2 Polarization Index (PI) .........................................................................42
5.7.3 Dielectric Discharge Testing (DD)........................................................43
Step Voltage testing....................................................................................45
Withstanding Voltage Test..........................................................................47
True RMS Voltmeter...................................................................................49
6Communication.................................................................................................50
7Maintenance ......................................................................................................51
Batteries insertion and replacement ...........................................................51
Cleaning......................................................................................................53
Periodic calibration .....................................................................................53
Service........................................................................................................53
8Technical specifications...................................................................................54
True RMS voltmeter....................................................................................56
General data...............................................................................................57

MI 3209 TeraOhmLT 10kV General description
5
1 General Description
Features
TeraOhmLT 10kV (MI 3209) is a portable battery or mains powered test instrument with
excellent IP protection (IP65), intended for diagnosing of Insulation Resistance by using
high test voltages of up to 10 kV. It is designed and produced with the extensive
knowledge and experience acquired through many years of working in this field.
Available functions and features offered by the TeraOhmLT 10kV meter:
➢Wide measuring range (5 kΩ ... 10 TΩ);
➢Insulation Measurement;
➢Step Voltage Test;
➢Withstanding Voltage Test (DC) up to 10 kV;
➢Voltage and frequency measurement up to 550 V TRMS
➢Polarization Index (PI);
➢Dielectric Absorption ratio (DAR);
➢Dielectric Discharge ratio (DD);
➢Graph R(t);
➢Adjustable test voltage (50 V...10 kV) 50 V and 100 V step;
➢Programmable timer;
➢Automatic discharge of test object after completion of measurement;
➢Capacitance measurement;
➢Input AC current noise rejection (1 mA@600 V);
➢High voltage breakdown detection;
➢Limit status;
➢Additional averaging of the result (5, 10, 30, 60)
➢USB and RS232 communication;
➢High overvoltage category CAT IV / 600 V.
A 320x240 dot matrix LCD offers easy-to-read results and all associated parameters.
The operation is straightforward and clear to enable the user to operate the instrument
without the need for special training (except reading and understanding this Instruction
Manual).
Test results can be stored on the instrument. PC software HVLink PRO that is supplied
as a part of standard set enables transfer of measured results to PC where can be
analyzed or printed.

MI 3209 TeraOhmLT 10kV Safety and operational considerations
6
2 Safety and operational considerations
Warnings and notes
In order to maintain the highest level of operator safety while carrying out various tests
and measurements Metrel recommends keeping your TeraOhmLT 10kV test equipment
in good condition and undamaged. When using this test equipment, consider the following
general warnings:
❑The symbol on the test equipment means »Read the Instruction manual with
special care for safe operation«. The symbol requires an action!
❑The symbol on the test equipment means “Hazardous voltage may be
present at the test terminals!”.
❑If the test equipment is used in a manner not specified in this Instruction manual,
the protection provided by the equipment could be impaired!
❑Read this Instruction manual carefully, otherwise the use of the test equipment may
be dangerous for the operator, the test equipment itself or for the tested object!
❑Do not use the test equipment or any of the accessories if any damage is noticed!
❑Consider all generally known precautions in order to avoid risk of electric shock
while dealing with hazardous voltages! Act according to requirements of EN 50191
or similar standard dealing with safety at test premises.
❑Do not connect the test equipment to a mains voltage different from the one defined
on the label adjacent to the mains connector, otherwise it may be damaged.
❑Service intervention or adjustment is only allowed to be carried out by competent
authorized personnel!
❑Hazardous voltages exist inside the test equipment. Disconnect all test leads,
remove the power supply cable and switch off the test equipment before opening
the battery compartment.
❑All normal safety precautions must be taken in order to avoid risk of electric shock
while working on electrical installations!
❑When working on high capacitive loads (more than 4 nF), use personal protective
equipment (gloves,..). Do not use communication ports during the measurement.
❑Do not use the equipment in a wet environment, around explosive gas, vapour or
dust.
❑Only adequately trained and competent persons may operate the equipment.
Warnings related to measurement functions:
Working with the instrument
❑Use only standard or optional test accessories supplied by your distributor!
❑Test tips should only be used for TRMS voltage measurement (CAT IV 600 V).

MI 3209 TeraOhmLT 10kV Safety and operational considerations
7
❑Always connect accessories to the test equipment and to the test object before
starting high voltage measurement. Donot touch test leads or crocodile clips during
measurement.
❑Do not touch any conductive parts of equipment under test during the test, risk of
electric shock!
❑Make sure that the tested object is disconnected (mains voltage disconnected) and
de-energized before connecting the test leads and starting the measurement
(except Voltage measurement)!
❑In case of a capacitive test object, automatic discharge of the object may not be
done immediately after finishing the measurement.
❑Do not connect test terminals to an external voltage higher than 600 V DC or AC
(CAT IV environment) to prevent any damage to the test equipment!
❑In rare cases (internal fault) the test equipment can behave in an uncontrolled
manner (LCD blinking, freezing, not responding to keys, etc.). In this case consider
the test equipment and the test object as hazardous live, and perform all safety
measures to turn off (reset) the test equipment and to discharge the test object
manually!
❑Make sure, that tested object is isolated from earth!
Handling with capacitive loads
❑Note that 40 nF charged to 1 kV or 4 nF charged to 10 kV are hazardous live!
❑Never touch the measured object during the testing until it is totally discharged
automatically and manually!
❑Because of dielectric absorption, capacitive test objects (capacitors, cables,
transformers, etc.) must be shorted out after the measuring process is completed.
Note:
❑For manual discharge Metrel recommends the use of A 1513 Discharge link. The
internal discharge resistors of A 1513 ensure a damped discharge up to 10 uF at
10 kV.
Warnings related to Batteries:
❑Never dispose of the batteries in a fire as it may cause them to explode or
generate a toxic gas
❑Do not attempt to disassemble, crush or puncture the batteries in any way,
as it could cause leakage of sulfuric acid that could cause injury.
❑Do not short circuit or reverse polarity the external contacts on a battery.
❑Keep the battery away from children.
❑Avoid exposing the battery to excessive shock/impacts or vibration.
❑Do not use a damaged battery.
❑Instrument uses Valve Regulated (sealed) Lead –Acid battery (LC –
R123R4PG or MW 3.4-12). It is designed to automatically charge and maintain
battery capacity according to the use.

MI 3209 TeraOhmLT 10kV Safety and operational considerations
8
Battery and charging of Lead –Acid battery
The instrument is designed to be powered by rechargeable Lead –Acid battery or with
mains supply. The LCD contains an indication of battery condition and the power source
(upper left section of LCD). In case the battery is too weak the instrument indicates this
as shown in Figure 2.1.
Symbol:
Indication of low battery.
Figure 2.1: Battery test
The battery is charged whenever the power supply is connected to the instrument. The
power supply socket is shown in Figure 2.2. Internal circuit controls (CC, CV) charging
and assures maximum battery lifetime. Nominal operating time is declared for battery with
nominal capacity of 3.4 Ah.
Figure 2.2: Power supply socket (C7)
The instrument automatically recognizes the connected power supply and begins
charging.
Symbol:
Indication of battery charging
Figure 2.3: Charging indication
Battery and charging characteristic
Typical
Battery type
LC-R123R4PG / MW 3.4-12
Charging mode
CC / CV
Nominal voltage
12.0 V
Rated capacity
3.4 Ah
Max charging voltage
14.0 V
Max charging current
1.2 A
Max discharge current
2.5 A
Typical charging time
4 hours

MI 3209 TeraOhmLT 10kV Safety and operational considerations
9
Typical charging profile which is also used in this instrument is shown in Figure 2.4.
ICH/8
Fastcharge Safety Time
Precharge
Time
Current Regulation Voltage Regulation
ICH
VREG
VLOWV
Charge
Current
Charge
Voltage
Figure 2.4: Typical charging profile
where:
VREG ...............................Battery charging voltage
VLOWV..............................Precharge threshold voltage
ICH...................................Battery charging current
ICH/8.................................1/8 of the charging current
2.2.1 Precharge
On power up, if the battery voltage is below the VLOWV threshold, the charger applies 1/8
of the charging current to the battery. The precharge feature is intended to revive deeply
discharged battery. If the VLOWV threshold is not reached within 30 minutes of initiating
precharge, the charger turns off and a FAULT is indicated.
Figure 2.5: No battery indication
Note:
❑As a safety backup, the charger also provides an internal 5-hour charge timer for
fast charge.

MI 3209 TeraOhmLT 10kV Safety and operational considerations
10
Typical charging time is 4 hours in the temperature range of 5°C to 60°C.
Ich/8
Ich
TLTF
TCOOL
TWARM
THTF
Charge
Suspended
Charge
Suspended
Temperature
Current
Charge
Figure 2.6: Typical charging current vs temperature profile
where:
TLTF.................................Cold temperature threshold (typ. -15°C)
TCOOL..............................Cool temperature threshold (typ. 0°C)
TWARM .............................Warm temperature threshold (typ. +60°C)
THTF ................................Hot temperature threshold (typ. +75°C)
The charger continuously monitors battery temperature. To initiate a charge cycle, the
battery temperature must be within the TLTF to THTF thresholds. If battery temperature is
outside of this range, the controller suspends charge and waits until the battery
temperature is within the TLTF to THTF range.
If the battery temperature is between the TLTF and TCOOL thresholds or between the TWARM
and THTW thresholds, charge is automatically reduced to ICH/8 (1/8 of the charging current).

MI 3209 TeraOhmLT 10kV Safety and operational considerations
11
Standards applied
The TeraOhmLT 10kV instrument is manufactured and tested in accordance with the
following regulations:
Electromagnetic compatibility (EMC)
EN 61326
Electrical equipment for measurement, control and laboratory
use –EMC requirements Class A
Safety (LVD)
EN 61010 - 1
Safety requirements for electrical equipment for measurement,
control and laboratory use –Part 1: General requirements
EN 61010 - 2 - 030
Safety requirements for electrical equipment for measurement,
control and laboratory use –Part 2-030: Particular requirements
for testing and measuring circuits
EN 61010 - 2 - 033
Safety requirements for electrical equipment for measurement,
control and laboratory use –Part 2-033: Particular requirements
for hand-held multimeters and other meters, for domestic and
professional use, capable of measuring mains voltage
EN 61010 - 031
Safety requirements for hand-held probe assemblies for electrical
measurement and test.
Some further recommendations
IEEE 43 –2000
Recommended Practice for Testing Insulation Resistance of Rotating
Machinery:
❑1 MΩ + 1 MΩ / 1000 V rating of equipment for insulation systems prior to 1970;
❑5 MΩ for random wound motors under 600 Volts;
❑100 MΩ for form wound motors over 600 Volts, and armatures;
IEC 60439-1
Low-voltage switchgear and control gear assemblies - Part 1:
Type-tested and partially type-tested assemblies:
❑Scope of the insulation resistance test: alternative method for verification of
dielectric properties by insulation resistance measurement;
❑Description: a d.c. test voltage (500 V) is applied to the insulation and its resistance
is measured. Insulation is proper, if its resistance is high enough (1000 Ω / V of
circuit rated voltage);
IEC 61558
Isolating transformers and safety isolating transformers:
❑Test voltage: 500 V, measurement period: 1 min;
❑Minimum insulation resistance for basic insulation: 2 MΩ;
❑Minimum insulation resistance for supplementary insulation: 5 MΩ;
❑Minimum insulation resistance for reinforced insulation: 7 MΩ;
Note about EN and IEC standards:
❑Text of this manual contains references to European standards. All standards of
EN 6XXXX (e.g. EN 61010) series are equivalent to IEC standards with the same
number (e.g. IEC 61010) and differ only in amended parts required by European
harmonization procedure.

MI 3209 TeraOhmLT 10kV Instrument description
12
3 Instrument description
Instrument casing
The instrument is housed in a plastic box that maintains the protection class defined in
the general specifications.
Operator’s panel
The operator’s panel is shown in Figure 3.1 below.
Figure 3.1: The operator’s panel
Keypad Section:
1
START / STOP
Start or stop measurement.
2
ON / OFF
Switches the instrument power on or off.
The instrument automatically turns off 15 minutes after the
last key was pressed.
3
MEM
Store / recall / clear tests in memory of the instrument.
4
SELECT
To enter set-up mode for the selected function or to select the
active parameter to be set.
5,6

Select an option upward, downward.
7,8
➢
Decrease, increase the selected parameter.
9
ESC
Exit the selected mode.
10
☼
Turn the display backlight ON or OFF.
Instrument’s RESET (hold key for 5 s or more).
Display Section:
19
High voltage warning light (red).
Terminal Section:
11
+ Rx
Positive high voltage output terminal.

MI 3209 TeraOhmLT 10kV Instrument description
13
12,13
GUARD
Guard input terminals.
14
- Rx
Negative high voltage input terminal.
Power and Communication Section:
18
C7
Input power supply socket (C7)
16
USB
USB communication port (standard USB connector - type B)
17
RS232
RS232 communication port (standard RS232 9-pin D
female)
Warnings!
❑Maximum allowed voltage between any test terminal and ground is 600 V!
❑Maximum allowed voltage between test terminals is 600 V!
❑Use original test accessories only!
❑Max. connection time of tested object with external voltage up to 600 V is
5 min (possible overheating of instrument even in OFF position).

MI 3209 TeraOhmLT 10kV Instrument description
14
Accessories
The accessories consist of standard and optional accessories. Optional accessories can
be delivered upon request. See attached list for standard configuration and options or
contact your distributor or see the METREL home page: http://www.metrel.si.
3.3.1 Test leads
The standard length of high voltage shielded test leads with (red, black) banana
connectors is 3 m; optional lengths are 8 m and 15 m. For more details see attached list
for standard configuration and options or contact your distributor or see the METREL
home page: http://www.metrel.si.
All test leads are made of high voltage shielded cable, because shielded cable provides
higher accuracy and immunity to disturbance of measurements that can occur in industrial
environments.
High voltage shielded test leads with High voltage alligator clips.
Application notes:
This test leads are designed for diagnostic
testing of insulation. They can also be used for
hand held testing with test voltages up to 5 kV
d.c..
Insulation ratings:
❑High voltage banana connectors (red,
black): 10 kV d.c. (basic insulation),
5 kV d.c. (reinforced insulation);
❑Alligator clips (red, black):
10 kV d.c. (basic insulation),
5 kV d.c. (reinforced insulation);
❑Guard banana connector (green): 600
V CAT IV (reinforced insulation);
❑Cable (yellow): 12 kV (shielded).
Figure 3.2: HV test leads with alligator clips
Guard test lead with alligator clip
Insulation ratings:
❑Guard test lead with banana
connectors (green): 600 V CAT IV
(reinforced insulation);
❑Alligator clip (green): 600 V CAT IV
(reinforced insulation)
Figure 3.3: Guard lead with alligator clip

MI 3209 TeraOhmLT 10kV Instrument description
15
Test tips
Application notes:
❑Test tips applied on High voltage
shielded test leads are designed for
CAT IV 600 V TRMS voltage
measurement.
Figure 3.4: Test tips

MI 3209 TeraOhmLT 10kV Instrument description
16
Display organization
Figure 3.5: Typical function display and graph screen
1
Measurement result window
2
Measurement control window
3
Messages window
4
Battery, time and communication indication
5
Measurement result line
6
Graphical presentation of measured data
3.4.1 Measurement result window
Measurement window shows all relevant data during measurement campaign.
Figure 3.6: Measurement window
Measured Insulation
resistance
Is shown in the center of a screen with the largest font. During
measurement campaign this result is refreshed every few
seconds. When the measurement is completed, result is hold on
screen, until new measurement is started.

MI 3209 TeraOhmLT 10kV Instrument description
17
Bar graph
Graphically represents measured insulation resistance in respect
to the measurement range. It also displays limit value if it is
enabled.
U
Shows the output voltage. During measurement campaign this
result is refreshed every few seconds. When the measurement is
completed, result is hold on screen, until new measurement is
started.
I
Shows the input current. During measurement campaign this
result is refreshed every few seconds. When the measurement is
completed, result is hold on screen, until new measurement is
started.
C
Shows the capacitance measured at the output terminals. Value
of capacitance is measured during the final discharge of the test
object.
R1, R2, R3
Show resistances measured at Timer1, Timer2 and Timer3. When
the measurement is completed, result is hold on screen, until new
measurement is started (appears only in Diagnostic Test).
R1, R2, R3,R4, R5
Show resistances measured at steps one to five. When the
measurement is completed, result is hold on screen, until new
measurement is started (appears only in Step Voltage Test).
U1, U2, U3, U4, U5
Show voltages measured at steps one to five. When the
measurement is completed, result is hold on screen, until new
measurement is started (appears only in Step Voltage Test).
DAR
Show the Dielectric Absorption Ratio. When the measurement is
completed, result is hold on screen, until new measurement is
started (appears only in Diagnostic Test).
PI
Show the Polarization Index. When the measurement is
completed, result is hold on screen, until new measurement is
started (appears only in Diagnostic Test).
DD
Show the Dielectric Discharge result. When the measurement is
completed, result is hold on screen, until new measurement is
started (appears only in Diagnostic Test).
f
Shows frequency of the measured voltage (appears only in True
RMS Voltmeter).
t
Shows test time (mm:ss).
3.4.2 Measurement control window
Control window permit user to modify control measurement parameters.
Figure 3.7: Control window

MI 3209 TeraOhmLT 10kV Instrument description
18
Un
Allows user to set the desired test voltage.
Timer1
Allows user to set the desired measurement duration in Insulation
Resistance test.
Delay for starting DAR measurement in Diagnostic test.
(mm:ss) –step 1 s (max time 99 min).
Timer2
Delay for starting PI measurement (mm:ss) –step 1 s (max time
99 min).
Timer3
Allows user to set the desired measurement duration (mm:ss) –
step 1 s (max time 99 min).
DD
Allows user to enable or disable Dielectric Discharge
measurement.
Itrgg
Allows user to set the desired trigger level –step 100 μA (max
current 5 mA).
Tstart
Allows user to set the start test voltage time (mm:ss) –step 1s
(max time 99 min).
Tend
Allows user to set the constant end test voltage time (mm:ss) –
step 1 s (max time 99 min).
Ustart
Allows user to set the desired start test voltage.
Uend
Allows user to set the desired end test voltage.
Tramp
Allows user to set the duration of the test ramp (mm:ss) –step 1
s (max time 99 min).
HI Lim
Allows user to set the high limit (value is evaluated at the end of
the measurement).
AVG
Allows user to set the additional averaging of the result (OFF, 5,
10, 30, 60).
3.4.3 Message window
In the message field warnings and messages are displayed.
Figure 3.8: Message window

MI 3209 TeraOhmLT 10kV Instrument description
19
High voltage is present on measuring terminals (> 50 V rms).
Test result can be saved.
AC noise is present on the measuring terminals (+ Rx, - Rx).
A Breakdown or Over voltage event has accrued.
Instrument is overheated. Measurement process is disabled.
Graph is enabled.
Graph logging is enabled (internal Flash memory).
Internal Flash memory is full (graph logging is disabled).
Measurement result is within defined limits.
Measurement result is out of defined limits.
3.4.4 Battery, time and communication indication
These symbols indicate the charge condition of a battery, charger connection and
communication status. Time indication is also present.
Battery capacity indication.
Low battery.
Recharge the battery.
Recharging in progress (if mains supply cable is connected).
Time indication (hh:mm).
USB communication is enabled.
Note:
❑Date and time are attached to each stored result.

MI 3209 TeraOhmLT 10kV Instrument description
20
3.4.5 Measurement result line
R
Shows Insulation resistance. During measurement campaign this
result is refreshed every few seconds. When the measurement is
completed, it represents Insulation resistance at cursor position.
U
Shows the output voltage. During measurement campaign this
result is refreshed every few seconds. When the measurement is
completed, it represents output voltage at cursor position.
t
Shows test time (mm:ss). When the measurement is completed,
it represents time at cursor position.
Note:
❑Averaging in measurement result line is disabled during measurement campaign
in all functions regardless of settings.
3.4.6 Graphical presentation of measured data
Figure 3.9: Graph screen
Measured or averaged Insulation resistance values in relation to time of measurement are
represented in this two-dimensional R/t diagram. Online plotting, during measurement,
can also be observed. When the measurement is completed, cursor is attached to the
graph for detail analysis.
3.4.7 Backlight operation
After turning the instrument ON the LCD backlight is automatically turned ON. It can be
turned OFF and ON by simply clicking the ☼(LIGHT) key.
Note:
❑If you press and hold the Light (☼) key for approximately 5 s the instrument will
RESET!