TeraOhm 5kV Plus
MI 3201
User Manual
Version 1.7 Code No. 20 751 272
Distributor:
Producer:
METREL d.d.
Ljubljanska 77
SI-1354 Horjul
Tel.: +386 1 75 58 200
Fax: +386 1 75 49 226
E-mail: metrel@metre.si
http://www.metrel.si
Mark on your equipment certifies that this equipment meets the requirements of the EU
(European Union) concerning safety and interference causing equipment regulations
© 2008 Metrel
No part of this publication may be reproduced or utilized in any form or by any means
without permission in writing from METREL.
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MI 3201 TeraOhm 5 kV Plus Table of contents
Table of contents
1 General introduction ........................................................................................... 4
1.1 Features..................................................................................................... 4
1.2 Applied Standards...................................................................................... 4
2 Instrument Description........................................................................................ 5
2.1 Instrument Casing ...................................................................................... 5
2.2 Operator’s Panel ........................................................................................ 5
2.3 Connectors.................................................................................................6
2.4 Accessories................................................................................................7
2.5 Test leads................................................................................................... 7
2.5.1 High voltage shielded test tips with High voltage alligator clips .............. 8
2.5.2 Guard test lead with alligator clips.......................................................... 8
3 Warnings ............................................................................................................ 9
4 Performing measurements ............................................................................... 11
4.1 Switching on the instrument ..................................................................... 11
4.1.1 Configuration ........................................................................................ 12
4.1.2 Setup .................................................................................................... 13
5 Measurements.................................................................................................. 15
5.1 General Information about High DC voltage testing................................. 15
5.2 Guard terminal.......................................................................................... 19
5.3 Filter options............................................................................................. 20
5.4 Voltage measurement .............................................................................. 21
5.5 Insulation Resistance measurement ........................................................ 22
5.6 Diagnostic Test......................................................................................... 26
5.7 Step Voltage Insulation Resistance testing .............................................. 32
5.8 Withstanding voltage................................................................................ 36
6 Working with your Results................................................................................ 39
6.1 Storing, Recalling and Clearing Results................................................... 39
6.2 Transferring Data to a PC......................................................................... 41
7 Maintenance..................................................................................................... 42
7.1 Inspection................................................................................................. 42
7.2 Inserting and charging batteries for the first time...................................... 42
7.3 Replacing and charging batteries............................................................. 42
7.4 Cleaning................................................................................................... 44
7.5 Calibration................................................................................................ 44
7.6 Service ..................................................................................................... 44
8 Specifications ................................................................................................... 45
8.1 Measurement specifications..................................................................... 45
8.2 General specifications.............................................................................. 48
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MI 3201 TeraOhm 5 kV Plus General introduction
1 General introduction
1.1 Features
The TeraOhm 5kV Plus Tester is a portable battery / mains powered test instrument
intended for the testing of Insulation Resistance by using high test voltages of up to
5kV.
The instrument is designed and produced with the extensive knowledge and experience
acquired through many years of working in this sector.
Available functions offered by the TeraOhm 5kV Plus Tester:
High insulation resistance measurement up to 10 T
- Programmable test voltage from 250 V up to 5 kV, steps 25 V
- R(t) Graphs
- Programmable timer (1s up to 100 min)
- Automatic discharge of test object after completion of measurement
- Capacitance measurement
Insulation resistance measurement versus test voltage (step-up voltage test)
- Five discrete test voltages proportionately set within preset test voltage range
- Programmable timer 1 min up to 30 min per step
Polarization Index (PI), Dielectric Absorption ratio (DAR) and Dielectric Discharge
(DD) ratio
- PI = RINS (t2) / RINS (t1)
DAR = R
-
- DD = Idis
Withstanding voltage (DC) up to 5 kV
- Programmable ramp test voltage from 250 V up to 5 kV
- High resolution ramp (approx. 25 V per step)
- Programmable threshold current up to 5 mA
Voltage and frequency measurement up to 600 V AC/DC
A 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 Users
Manual).
Test results can be stored on the instrument. The new professional PC SW enables
straightforward transfer of test results and other parameters in both directions between
the test instrument and PC.
1min
1min
/ R
15s
/ CU
1.2 Applied Standards
Instrument operation IEC / EN 61557-2
Electromagnetic compatibility (EMC) EN 61326 Class B
Safety EN 61010-1 (instrument),
EN 61010-031 (accessories)
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MI 3201 TeraOhm 5 kV Plus Instrument Description
2 Instrument Description
2.1 Instrument Casing
The instrument is housed in a plastic box that maintains the protection class defined in
the general specifications.
2.2 Operator’s Panel
The operator’s panel is shown in Fig. 1 below.
Fig. 1. Front panel
Legend:
1........... START/STOP key to start or stop any measurement.
2........... ON/OFF key to switch the instrument ON or OFF.
3........... MEM key to store, recall and erase results.
4........... SELECT key to enter set-up mode for the selected function or to select the active
parameter to be set.
5...........
6........... cursor key to select an option downward.
7........... cursor key to decrease the selected parameter.
8...........
cursor key to select an option upward.
cursor key to increase the selected parameter.
4
9..........ESC key to exit the selected mode.
10........Light key to turn the display backlight ON or OFF.
5
MI 3201 TeraOhm 5 kV Plus Instrument Description
2.3 Connectors
The TeraOhm 5 kV Tester contains the following connections:
- Connection of test leads to four banana safety sockets (Fig. 2),
- Mains supply cable connection to the mains socket and communication socket (USB
and RS232) (Fig. 3).
Fig. 2. Test leads connector
1..........Negative Insulation Resistance test terminal. (-OUT)
2..........GUARD test terminals intended to lead away potential leakage current while
measuring the Insulation. Both green sockets are connected together inside the
instrument.
3..........Positive Insulation Resistance test terminal (+OUT)
Use original test accessories only!
Max. allowed external voltage between test terminals and ground is 600V!
Max. allowed external voltage between test terminals is 600V!
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MI 3201 TeraOhm 5 kV Plus Instrument Description
Fig. 3. Communication and Mains connector
1..........Galvanic separated RS232 connector to connect the instrument to PC.
2..........Galvanic separated USB connector to connect the instrument to PC.
3..........Mains connector to connect the instrument to the mains supply.
Use original mains supply cable only!
2.4 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.
2.5 Test leads
The standard length of test leads is 2m, optional lengths are 8m and 15m. 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 environment.
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MI 3201 TeraOhm 5 kV Plus Instrument Description
2.5.1 High voltage shielded test tips with High voltage alligator clips
Application notes:
These test leads is designed for diagnostic testing of
insulation and also for hand held testing of insulation.
Insulation ratings:
- High voltage banana connector (red, black): 5kV d.c
(double insulation);
- High voltage tip (red, black): 5kV d.c ( double insulation);
- Alligator (red, black): 5kV d.c (double insulation);
- Guard banana connector (green): 600V CAT IV (double
insulation);
- Cable (yellow): 12kV (shielded).
2.5.2 Guard test lead with alligator clips
Insulation ratings:
- Guard test lead with banana connectors (green): 600V CAT IV (double insulation);
- Alligator (green): 600V CAT IV (double insulation).
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MI 3201 TeraOhm 5 kV Plus Warnings
3 Warnings
In order to reach the highest level of operator’s safety while carrying out various
measurements and tests using the TeraOhm 5kV Plus Tester, as well as to ensure that
the test equipment remains undamaged, it is necessary to consider the following
warnings:
MEANING OF SYMBOLS
Symbol on the instrument means “Read the User Manual with special
care!”.
Symbol on the instrument means “Hazardous voltage higher than 70V
may be present at the test terminals!”.
GENERAL PRECAUTIONS
If the test equipment is used in a manner not specified in this Users Manual,
the protection provided by the equipment may be impaired!
Do not use the instrument and accessories, if any damage is noticed!
Consider all generally known precautions in order to avoid the risk of electric
shock while dealing with electric installations!
Service intervention or recalibration procedure can be carried out only by a
competent and authorized person!
Only adequately trained and competent persons may operate the instrument.
A dot matrix LCD offers easy-to-read results and all associated parameters.
Operation is simple and clear; the operator does not need any special training
(except reading and understanding this Users Manual) to operate the
instrument.
BATTERIES
Disconnect all test leads, main supply cable and switch the power off before
opening the Battery cover!
Use only NiMh rechargeable batteries (C size)!
EXTERNAL VOLTAGES
Do not connect the instrument to a mains voltage different from the one
defined on the label adjacent to the mains connector, otherwise the instrument
may be damaged.
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 instrument!
WORKING WITH THE INSTRUMENT
Use only standard or optional test accessories supplied by your distributor!
Equipment under test must be switched off i.e. (de-energized) before test
leads are connected to the equipment.
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MI 3201 TeraOhm 5 kV Plus Warnings
Do not touch any conductive parts of equipment under test during the test.
Make sure that the tested object is disconnected (mains voltage disconnected)
before starting the Insulation Resistance measurement!
Do not touch the tested object whilst testing it, risk of electric shock!
In case of a capacitive test object (long tested cable etc.), automatic discharge
of the object may not be done immediately after finishing the measurement –
“Please wait, discharging” message will be displayed.
HANDLING WITH CAPACITIVE LOADS
Note that 40 nF charged to 1 kV or 9 nF charged to 5 kV are hazardous live!
Never touch the measured object during the testing until it is totally
discharged.
Maximum external voltage between any two leads is 600 V (CAT IV
environment).
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MI 3201 TeraOhm 5 kV Plus Performing measurements
4 Performing measurements
4.1 Switching on the instrument
Auto-calibration
The instrument is switched ON by pressing the ON/OFF key. After turning on, the
instrument will execute the auto-calibration (Fig. 4).
Note:
If batteries are defective or missing and the instrument is powered from mains supply,
the instrument will not turn ON.
Measuring test leads should be disconnected during auto-calibration. If not, the autocalibration procedure could be false and instrument will require disconnection of the test
leads and repeat switching OFF and ON.
After finishing the auto-calibration, the MAIN MENU (Fig.5) will appear and instrument
is ready for normal operation.
Auto-calibration prevents the reduction in accuracy when measuring very low currents.
It compensates the effects caused by ageing, temperature and humidity changes etc.
A new auto-calibration is recommended when the temperature changes by more than
5C.
Fig. 4. Auto-calibration state
Note:
If the instrument detects an incorrect state during the auto-calibration, the following
warning message will be displayed:
ERROR!
-TEST LEADS CONNECTED:
DISCONNECT AND SWITCH ON THE INSTRUMENT AGAIN
- CONDITIONS OUT OF RANGE: PRESS START TO CONTINUE
Possible reasons for out of range conditions are excessive humidity, excessively high
temperature, etc. In this case it is possible to perform measurements by pressing the
START/STOP button again but results could be out of technical specification.
Mains powered instrument operation
If you connect instrument to the mains supply when instrument is turned OFF, internal
charger will begin to charge the batteries but instrument will remain turned OFF. In
Fig. 5. Main Menu
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MI 3201 TeraOhm 5 kV Plus Performing measurements
bottom left angle of LCD screen the plug character and the flashing battery indicator will
appear to indicate that the batteries are charging.
Note: If batteries are defective or missing, the charger will not work. In lower left corner
of LCD screen only plug character will be appeared (without battery indicator).
If the instrument is connected to the mains supply when the instrument is turned ON,
the instrument will automatically switch from the battery supply to the main supply. In
bottom left corner of LCD screen, the plug character will appear. If instrument is not in
measuring mode*, the internal charger will begin to charge the batteries. In bottom left
corner of LCD screen battery indicator will start to flash, indicating that the batteries are
charging.
Note: It is not recommended to connect or disconnect the instrument to mains supply
while the instrument is in measuring mode*.
*measuring mode: When the instrument is performing a test.
Backlight operation (battery powered instrument)
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.
Backlight operation (mains powered instrument)
After turning the instrument ON the LCD backlight is automatically turned OFF. It can be
turned OFF and ON by simply clicking the LIGHT key.
Off function
The instrument can be switched OFF only by pressing the ON/OFF key. The auto-off
function is not available to allow long-term measurements to be performed.
4.1.1 Configuration
The configuration function enables the selection and adjustment of parameters (Table
1a.) of the measurements. In addition memorized results can be cleared in this menu.
(Fig. 5a).
In the lower section of the display the power supply status is shown.
The following procedure must be carried out when adjusting some of the configuration
parameters:
1. Use and arrows to select parameter (line) to be adjusted.
2. Use and arrows to change the value of the selected parameter. If there are
two or more sub-parameters in one line (e.g. date and time) then use the SELECT
key to skip to the next sub-parameters and back.
To clear all memory locations:
1. Select Configuration from the main menu
1. Highlight the Memory Clear option using and arrows.
2. Press the SELECT key, (“Press MEM to confirm!” message will be displayed).
3. Press the MEM key to clear all memory locations or ESC to cancel the activity.
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MI 3201 TeraOhm 5 kV Plus Performing measurements
Fig. 5a. Configuration menu
Parameter Value Note
Memory clear
Filter
DIAG.
Starting time
Clear all memory locations
Fil1, Fil2, Fil3,
Fil0
Selection of noise rejecting filter, see the chapter
5.3. Filter Option
0%..90% Adjustment of start of the timer in the
DIAGNOSTIC TEST functions, according to the
nominal voltage Unominal. See additional
explanation in chapter 5.6.
Table 1a. Parameters in Configuration menu
4.1.2 Setup
The setup function enables the selection and adjustment of general parameters (Table
1b.) of the instrument (Fig. 5b).
In the lower section of the display the power supply status is shown.
The following procedure must be carried out when adjusting some of the configuration
parameters:
3. Use and arrows to select parameter (line) to be adjusted.
4. Use and arrows to change the value of the selected parameter. If there are
two or more sub-parameters in one line (e.g. date and time) then use the SELECT
key to skip to the next sub-parameters and back.
Fig. 5b. Setup menu
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MI 3201 TeraOhm 5 kV Plus Performing measurements
Parameter Value Note
Contrast
Time
Date
Com Port
Language
Initialization
0%..100% Adjustment of the LCD contrast
Set real time (hour: minute)
Set current date (day-month-year)
RS 232 2400,
RS 232 4800,
RS 232 9600,
RS 232 19200,
USB 115000
Set language
For internal factory and service maintenance only!
Table 1b. Parameters in Setup menu
Set communication mode and rate.
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MI 3201 TeraOhm 5 kV Plus Measurements
5 Measurements
5.1 General Information about High DC voltage testing
The purpose of insulation tests
Insulating materials are important parts of almost every electrical product. The
material’s properties depend not only on its compound characteristics but also on
temperature, pollution, moisture, ageing, electrical and mechanical stress, etc. Safety
and operational reliability require the regular maintenance and testing of the insulation
material to ensure it is kept in good operational condition. High voltage tests are used to
test insulating materials.
DC vs. AC testing voltage
Testing with a DC voltage is widely accepted as being as useful as testing with AC and /
or pulsed voltages. DC voltages can be used for breakdown tests especially where high
capacitive leakage currents interfere with measurements using AC or pulsed voltages.
DC is mostly used for insulation resistance measurement tests. In this type of test, the
voltage is defined by the appropriate product application group. This test voltage is
lower than the voltage used in the withstanding voltage test so the tests can be applied
more frequently without stressing the test material
Typical insulation tests
In general, insulation resistance tests consist of the following possible procedures:
- Simple insulation resistance measurement also called a spot test;
- Measurement of the relationship between voltage and insulation resistance;
- Measurement of the relationship between time and insulation resistance;
- Test of residual charge after the dielectric discharge.
The results of this test can indicate whether the replacement of the insulation system is
needed.
Typical examples of where testing insulation resistance and its diagnosis are
recommended are transformer and motor insulation systems, cables and other electrical
equipment.
Electrical representation of insulating material
Fig. 7 represents the equivalent electrical circuit of an insulating material
surface
Itest
+
material
Guard
Riss1
Cpi
Itest
PI
I
Ciso
Riss2
Riso
Rpi
-
Ciso
I
Fig. 7. Fig. 8.
15
I
RisoIRiss
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