Bender ISOMETER isoMIL425 User manual

Manual
EN
Insulation monitoring device for unearthed
IT AC-, AC/DC and DC systems (IT systems)
in military applications up to 3(N)AC, AC/DC 400 V
Software version: D0459 V1.xx
ISOMETER® isoMIL425
isoMIL425_D00203_03_M_XXEN/03.2019

Bender GmbH & Co. KG
Londorfer Str. 65 • 35305 Gruenberg • Germany
P.O. Box 1161 • 35301 Gruenberg • Germany
Tel.: [phone]
Fax: [phone]
E-mail: [email protected]
Web: http://www.bender.de
©Bender GmbH & Co. KG
All rights reserved.
Reprinting only with permission
of the publisher.
Subject to change!
Photos: Bender archives.

Table of contents
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isoMIL425_D00203_03_M_XXEN/03.2019
1. Important information .................................................................................... 6
1.1 How to use this manual ................................................................................. 6
1.2 Technical support: Service and support .................................................. 7
1.2.1 First level support ............................................................................................. 7
1.2.2 Repair service ..................................................................................................... 7
1.2.3 Field service ........................................................................................................ 8
1.3 Training courses ................................................................................................ 8
1.4 Delivery conditions .......................................................................................... 9
1.5 Inspection, transport and storage .............................................................. 9
1.6 Warranty and liability ...................................................................................... 9
1.7 Disposal ............................................................................................................ 10
2. Safety instructions ......................................................................................... 11
2.1 General safety instructions ........................................................................ 11
2.2 Work activities on electrical installations ............................................. 11
2.3 Intended use ................................................................................................... 12
3. Function ........................................................................................................... 13
3.1 Device features .............................................................................................. 13
3.2 Functional description ................................................................................ 14
3.2.1 Monitoring of the insulation resistance (R mode) ............................. 15
3.2.2 Monitoring of the insulation impedance (Z mode) .......................... 16
3.2.3 Undervoltage/overvoltage monitoring ................................................ 16
3.2.4 Self test/error codes ..................................................................................... 17
3.2.5 Malfunction ..................................................................................................... 19
3.2.6 Assignment of the alarm relays K1/K2 ................................................... 19
3.2.7 Measuring and response times ................................................................ 20
3.2.8 Password protection (on, OFF) ................................................................. 22
3.2.9 Factory setting FAC ...................................................................................... 22

Table of contents
4isoMIL425_D00203_03_M_XXEN/03.2019
3.2.10 External, combined test or reset button T/R ....................................... 22
3.2.11 Fault memory .................................................................................................. 22
3.2.12 History memory HiS ...................................................................................... 23
3.2.13 Interface/protocols ...................................................................................... 23
4. Installation, connection and commissioning ........................................... 25
4.1 Installation ....................................................................................................... 25
4.2 Wiring diagram .............................................................................................. 27
4.3 Commissioning .............................................................................................. 29
5. Operation of the device ............................................................................... 30
5.1 Display elements ........................................................................................... 31
5.2 Menu structure ............................................................................................... 32
5.3 Menu "AL" ........................................................................................................ 33
5.3.1 Response value setting ............................................................................... 33
5.4 Menu "out" ....................................................................................................... 34
5.4.1 Configuration of the relay operating mode ........................................ 34
5.4.2 Relay alarm assignment "r1" and "r2" and LED assignment ........... 34
5.4.3 Fault memory configuration .................................................................... 35
5.4.4 Interface configuration .............................................................................. 36
5.5 Menu "t" ............................................................................................................ 37
5.5.1 Time configuration ....................................................................................... 37
5.6 Menu "SEt" ....................................................................................................... 38
5.6.1 Function configuration ............................................................................... 38
5.7 Measuring value display and history memory .................................... 39
6. Data access using the BMS protocol .......................................................... 41

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isoMIL425_D00203_03_M_XXEN/03.2019
7. Data access using the Modbus RTU protocol ........................................... 42
7.1 Reading out the Modbus register from the ISOMETER® ................. 42
7.1.1 Command of the master to the ISOMETER® ........................................ 42
7.1.2 Answer of the ISOMETER® to the Master .............................................. 43
7.2 Write Modbus register (parameter setting) ......................................... 43
7.2.1 Command of the master to the ISOMETER® ........................................ 43
7.2.2 ISOMETER® answer to the Master ............................................................ 44
7.3 Exception code ............................................................................................... 44
7.3.1 Structure of the exception code .............................................................. 44
8. Modbus register assignment of the ISOMETER® ...................................... 45
8.1 Device-specific data type of the ISOMETER® ....................................... 51
8.1.1 Device name ................................................................................................... 51
8.1.2 Measuring values .......................................................................................... 52
8.1.2.1 Float = Floating point value of the channels .............................. 53
8.1.2.2 AT&T = Alarm type and test type (internal/external) .............. 54
8.1.2.3 R&U = Range and unit ......................................................................... 55
8.1.3 Alarm assignment of the relays ................................................................ 56
8.2 Channel descriptions ................................................................................... 57
9. IsoData data string ........................................................................................ 59
10. Technical data .............................................................................................. 61
10.1 Tabular presentation .................................................................................... 61
10.2 Standards, approvals and certifications ................................................ 65
10.3 Ordering information .................................................................................. 65

6isoMIL425_D00203_03_M_XXEN/03.2019
1. Important information
1.1 How to use this manual
Always keep this manual within easy reach for future reference.
To make it easier for you to understand and revisit certain sections in this man-
ual, we have used symbols to identify important instructions and information.
The meaning of these symbols is explained below:
This manual is intended for electrically skilled persons
working in electrical engineering and electronics.
DANGER
This signal word indicates that there is a high risk of danger
that will result in death or serious injury if not avoided.
WARNING
This signal word indicates a medium risk of danger that
can lead to death or serious injury if not avoided.
CAUTION
This signal word indicates a low level risk that can result in
minor or moderate injury or damage to property if not
avoided.

Important information
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isoMIL425_D00203_03_M_XXEN/03.2019
1.2 Technical support: Service and support
For commissioning and troubleshooting Bender offers you:
1.2.1 First level support
Technical support by phone or e-mail for all Bender products
 Questions concerning specific customer applications
 Commissioning
 Troubleshooting
Telephone: [phone] *
Fax: [phone]
In Germany only: 0700BenderHelp (Tel. and Fax)
E-Mail: [e-mail]
1.2.2 Repair service
 Repair, calibration, update and replacement service for Bender prod-
ucts
 Repairing, calibrating, testing and analysing Bender products
 Hardware and software update for Bender devices
 Delivery of replacement devices in the event of faulty or incorrectly
delivered Bender devices
 Extended warranty for Bender devices with in-house repair service or
replacement device at no extra cost
This symbol denotes information intended to assist the user
in making optimum use of the product.

Important information
8isoMIL425_D00203_03_M_XXEN/03.2019
Telephone: [phone]* (technical issues) *
[phone]**, -785** (sales)
Fax: [phone]
E-Mail: [e-mail]
1.2.3 Field service
On-site service for all Bender products
 Commissioning, parameter setting, maintenance, troubleshooting for
Bender products
 Analysis of the electrical installation in the building (power quality test,
EMC test, thermography)
 Training courses for customers
Telephone: [phone]**, -762 **(technical issues)
[phone]** (sales)
Fax: [phone]
E-Mail: [e-mail]
Internet: www.bender-de.com
*Available from 7.00 a.m. to 8.00 p.m. 365 days a year (CET/UTC+1)
**Mon-Thurs 7.00 a.m. - 8.00 p.m., Fr 7.00 a.m. - 13.00 p.m.
1.3 Training courses
Bender is happy to provide training regarding the use of test equipment.
The dates of training courses and workshops can be found on the Internet at
www.bender-de.com -> Know-how -> Seminars.

Important information
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isoMIL425_D00203_03_M_XXEN/03.2019
1.4 Delivery conditions
Bender sale and delivery conditions apply. For software products, the "Soft-
wareklausel zur Überlassung von Standard-Software als Teil von Lieferungen,
Ergänzung und Änderung der Allgemeinen Lieferbedingungen für Erzeug-
nisse und Leistungen der Elektroindustrie" (software clause in respect of the
licensing of standard software as part of deliveries, modifications and changes
to general delivery conditions for products and services in the electrical indus-
try) set out by the ZVEI (Zentralverband Elektrotechnik- und Elektronikindus-
trie e.V.) (German Electrical and Electronic Manufacturers' Association) also
applies.
Sale and delivery conditions can be obtained from Bender in printed or elec-
tronic format.
1.5 Inspection, transport and storage
Inspect the dispatch and equipment packaging for damage, and compare the
contents of the package with the delivery documents. In the event of damage
in transit, please contact Bender immediately.
The devices must only be stored in areas where they are protected from dust,
damp, and spray and dripping water, and in which the specified storage tem-
peratures can be ensured.
1.6 Warranty and liability
Warranty and liability claims in the event of injury to persons or damage to
property are excluded if they can be attributed to one or more of the follow-
ing causes:
 Improper use of the device.
 Incorrect mounting, commissioning, operation and maintenance of the
device.
 Failure to observe the instructions in this operating manual regarding
transport, commissioning, operation and maintenance of the device.
 Unauthorised changes to the device made by parties other than the

Important information
10 isoMIL425_D00203_03_M_XXEN/03.2019
manufacturer.
 Non-observance of technical data.
 Repairs carried out incorrectly and the use of replacement parts or
accessories not approved by the manufacturer.
 Catastrophes caused by external influences and force majeure.
 Mounting and installation with device combinations not recom-
mended by the manufacturer.
This operating manual, especially the safety instructions, must be observed by
all personnel working on the device. Furthermore, the rules and regulations
that apply for accident prevention at the place of use must be observed.
1.7 Disposal
Abide by the national regulations and laws governing the disposal of this de-
vice. Ask your supplier if you are not sure how to dispose of the old equip-
ment.
The directive on waste electrical and electronic equipment (WEEE directive)
and the directive on the restriction of certain hazardous substances in electri-
cal and electronic equipment (RoHS directive) apply in the European Commu-
nity. In Germany, these policies are implemented through the "Electrical and
Electronic Equipment Act" (ElektroG). According to this, the following applies:
 Electrical and electronic equipment are not part of household waste.
 Batteries and accumulators are not part of household waste and must
be disposed of in accordance with the regulations.
 Old electrical and electronic equipment from users other than private
households which was introduced to the market after 13th August
2005 must be taken back by the manufacturer and disposed of prop-
erly.
For more information on the disposal of Bender devices, refer to our
homepage at www.bender.de -> Service & support.

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2. Safety instructions
2.1 General safety instructions
Part of the device documentation in addition to this manual is the enclosed
"Safety instructions for Bender products".
2.2 Work activities on electrical installations
If the device is used outside the Federal Republic of Germany, the applicable
local standards and regulations must be complied with. The European stand-
ard EN 50110 can be used as a guide.
Only skilled persons are permitted to carry out the
work necessary to install, commission and run a de-
vice or system.
DANGER
Risk of electrocution due to electric shock!
Touching live parts of the system carries the risk of:
 An electric shock
 Damage to the electrical installation
 Destruction of the device
Before installing and connecting the device, make sure that
the installation has been de-energised. Observe the rules for
working on electrical installations.

Safety instructions
12 isoMIL425_D00203_03_M_XXEN/03.2019
2.3 Intended use
The ISOMETER® monitors the insulation resistance RF(R mode) or the insula-
tion impedance ZF(Z mode) of unearthed AC/DC main circuits (IT systems)
with nominal system voltages of 3(N)AC, AC, AC/DC or DC 0 … 400 V. DC com-
ponents existing in 3(N)AC, AC/DC systems do not influence the operating
characteristics, when a minimum load current of DC 10 mA flows. A separate
supply voltage Usallows deenergised systems to be monitored as well. The
maximum permissible system leakage capacitance Ceis 300 µF in R mode and
1µF in Z mode.
Any other use than that described in this manual is regarded as improper.
To ensure that the ISOMETER® functions correctly, an internal
resistance of
≤ 1 kΩ must exist between L1/+ and L2/- via the
source (e.g. the transformer) or the load.

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3. Function
3.1 Device features
 Monitoring of the insulation resistance RF(R mode) or the insulation
impedance ZF(Z mode) of unearthed 3(N)AC, AC and DC systems
(IT systems) with galvanically connected rectifiers or inverters
 Insulation impedance ZF(Z mode) for 50 Hz or 60 Hz
 Measurement of the nominal system voltage Un(True RMS) with und-
ervoltage and overvoltage detection
 Measurement of residual voltages system to earth (L+/PE and L-/PE)
 Automatic adaptation to the system leakage capacitance Ceup to
300 F in R mode and 1F in Z mode
 Automatic device self test with connection monitoring
 Selectable start-up delay, response delay and delay on release
 Two separately adjustable response ranges of 1…990 k (alarm 1,
alarm 2)
 Alarm signalling via LEDs ("AL1", "AL2"), a display and alarm relays ("K1",
"K2")
 N/C operation or N/O operation can be selected for the relays
 Measured value indication via multi-functional LCD
 Fault memory can be activated
 RS-485 (galvanically isolated) including the following protocols:
– BMS interface (Bender measuring device interface) for data
exchange with other Bender components
– Modbus RTU
– IsoData (for continuous data output)
 Password protection to prevent unauthorised parameter changes

Function
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3.2 Functional description
The ISOMETER® measures the insulation resistance RFand the system leakage
capacitance Cebetween the system to be monitored (L1/+, L2/-) and earth
(PE). Z mode (selectable in the "SEt" menu) calculates the insulation imped-
ance ZFfrom RFand Cewith a system frequency parameter fn= 50 Hz or
fn= 60 Hz. The RMS value of the nominal system voltage Unbetween L1/+ and
L2/-, as well as the residual voltages UL1e(between L1/+ and earth) and UL2e
(between L2/- and earth) are also measured.
From a minimum value of the nominal system voltage, the ISOMETER® deter-
mines the faulty conductor in % (represented by "R %"), which shows the dis-
tribution of the insulation resistance between conductors L1/+ and L2/-. The
distribution is indicated by a positive or negative sign preceding the insula-
tion resistance measurement. The value range of the faulty conductor is
±100 %:
The partial resistances can be calculated from the total insulation resistance RF
and the faulty conductor (R %) using the following formula:
Also from a minimum value of the nominal system voltage, the ISOMETER® de-
termines the insulation resistance RUGF from the residual voltages UL1e and
UL2e. It is an approximate value for one-sided insulation faults and can be used
as a trend indicator in cases where the ISOMETER® has to adapt to an RFand Ce
relation that varies considerably.
It is possible to assign the detected fault or the faulty conductor to an alarm
relay via the menu. If the values RF, ZFor Unexceed the response values acti-
vated in the "AL" menu, this will be indicated by the LEDs and relays "K1" and
Display Meaning
–100 % one-sided fault at conductor L2/-
0 % symmetrical fault
+100 % one-sided fault at conductor L1/+
Fault at conductor L1/+ RL1F = (200 % * RF)/(100 % + R %)
Fault at conductor L2/- RL2F = (200 % * RF)/(100 % – R %)

Function
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isoMIL425_D00203_03_M_XXEN/03.2019
"K2" according to the alarm assignment set in the "out" menu. In addition, the
operation of the relay (n.o./n.c.) can be set and the fault memory "M" activat-
ed.
If the values RF, ZFor Undo not exceed their release value (response value plus
hysteresis) for the period toff without interruption, the alarm relays will switch
back to their initial position and the alarm LEDs "AL1"/"AL2" stop lighting. If
the fault memory is activated, the alarm relays remain in alarm condition and
the LEDs light until the reset button "R" is pressed or the supply voltage Usis
interrupted.
The device function can be tested using the test button "T". Parameters are
assigned to the device via the LCD and the control buttons on the front panel;
this function can be password-protected. Parameterisation is also possible via
the BMS bus, for example by using the BMS Ethernet gateway (COM465IP) or
the Modbus RTU.
3.2.1 Monitoring of the insulation resistance (R mode)
The two parameters that monitor the insulation resistance, "R1" and "R2", can
be found in the response value menu "AL" (see table on Page 33). The value
"R1" can only be set higher than the value "R2". Each time the mode is
switched from R mode to Z mode, parameters "R1" and "R2", and hence the
monitoring of the insulation resistance RFwill be deactivated. In Z mode the
insulation impedance ZFis the main measured value and the measured insu-
lation resistance RFcan have tolerances depending on the system condition.
If required, the parameters "R1" and "R2" can also be activated in Z mode.
If the insulation resistance RFreaches or falls below the activated values "R1"
or "R2", an alarm message will be signalled. If RFexceeds the values "R1" or
"R2" plus the hysteresis value (see table on Page 33), the alarm will be cleared.

Function
16 isoMIL425_D00203_03_M_XXEN/03.2019
3.2.2 Monitoring of the insulation impedance (Z mode)
The parameters "Z1" and "Z2" for monitoring the insulation impedance ZFare
available in the "AL" response value menu only when Z mode is activated. The
value "Z1" must be set higher than value "Z2". The insulation impedance ZFfor
the selected system frequency fn(50 Hz or 60 Hz in the "SEt" menu) can be cal-
culated from the measured values RFand Ceusing the formula below:
The lower resistance component ofRFor Xce determines the amount of ZF. The
higher resistance component of RFor Xce can have a higher tolerance due to
the measuring signal resolution.
If the insulation impedance ZFreaches or falls below the activated values "Z1"
or "Z2", an alarm message will be signalled. If ZFexceeds the values "Z1" or
"Z2" plus the hysteresis value (see table on Page 33), the alarm will be cleared.
3.2.3 Undervoltage/overvoltage monitoring
In the response value menu "AL" (see Page 33), the parameters
("U <" and "U >") for monitoring the nominal system voltage Uncan be activat-
ed or deactivated. The maximum undervoltage value is limited by the over-
voltage value.
The RMS value of the nominal system voltage Unis monitored. If the nominal
system voltage Unreaches, falls below or exceeds the limit values ("U <" or
"U >"), an alarm will be signalled. If the maximum permissible system leakage
capacitance Ceset for the ISOMETER® is exceeded, an alarm message will be
initiated even when the overvoltage limit value has been deactivated. The
alarm will be deleted when the limit values plus the hysteresis (see Page 33)
are no longer violated.
Xce l
2π× fn ×Ce ×()
------------------------------------------=

Function
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3.2.4 Self test/error codes
The integrated self-test function checks the function of the insulation moni-
toring device and the connection monitoring checks the connections to the
system to be monitored. The alarm relays are not switched during the self test.
This can be changed using the parameter "test" in the alarm assignment
(Chapter 5.4 Menu "out"). During the test, the display indicates "tES".
When malfunctions are detected or connections are missing, the LEDs "ON"/
"AL1"/"AL2" flash. The respective error codes ("E.xx") will be indicated on the
display and the relay "K2" switches.
The relays can be assigned to a device error with the parameter"Err" in the
"out" menu in the alarm assignment.
Error codes
If, contrary to expectations, a device error should occur, error codes will ap-
pear on the display. Some of these are described below:
Error code Meaning
E.01
PE connection error
The connections "E" or "KE" to earth are interrupted.
Action:
Check connection, eliminate error. The error code will be
erased automatically once the error has been eliminated.
E.02
Connection error system (L1/+ , L2/-)
The internal resistance of the system is too high, the con-
nection "L1/+" or "L2/-" to the system is interrrupted or L1/+
and L2/- are connected in reverse polarity to the DC System
to be monitored (Un< -50 V).
Action:
Check connection, eliminate error. The error code will be
erased automatically once the error has been eliminated.
E.05 Measurement technique error/calibration invalid
For the current software version

Function
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Internal device errors "E.xx" can be caused by external disturbances or inter-
nal hardware errors. If the error message occurs again after restarting the
device or after a reset to factory settings (menu item "FAC") , the device must
be repaired.
After eliminating the fault, the alarm relays switch back automatically or they
return to the initial position by pressing the reset button.
The self test can take a few minutes. It can be suppressed for the duration of
the device start by setting the parameter in the menu "SEt" to
"S.Ct = off". This allows the ISOMETER® to enter measurement mode quickly
after connecting the supply voltage Us.
Automatic self test
After switching on the supply voltage Us, the device runs a self test and re-
peats it every 24 h (selectable: off, 1h, 24 h).
Manual self test
A self test is initiated by pressing the test button for a period greater than
1.5 s. While pressing the internal test button "T", all display elements available
for this device are shown.
E.07
The maximum permissible system leakage capacitance
Ce is exceeded.
Action:
Device not suitable for the existing system leakage capaci-
tance Ce: uninstall device.
E.08
Calibration error during the device test
Action:
If the error continues to exist after checking the device con-
nections, there is an error inside the device.

Function
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Connection monitoring
The connection monitoring, activated by the self test, checks the connections
of the terminals "E" and "KE" to the protective earth conductor (PE). When an
error is detected, the message device error ("Err") will be signalled and the er-
ror code "E.01" appears on the display.
The system connection monitoring is used to check the terminal connections
"L1/+" and "L2/-" to the system to be monitored. When an interruption or a
high-resistance connection between L1/+ and L2/- is detected via the internal
resistance of the system, the device error ("Err") will be signalled and the error
code "E.02" appears on the display. Since a test of the system connection may
take considerable time due to system disturbances or may even provide in-
correct results, the system connection monitoring can be disconnected using
the parameter "nEt" in the "SEt" menu.
3.2.5 Malfunction
In addition to the self test described above, several functions in the insulation
monitoring device are continuously checked during operation. If a fault is de-
tected, the device error ("Err") will be signalled, the error code "E.xx" appears
on the display as an identifier for the error type xx and the LEDs "ON"/"AL1"/
"AL2" will flash.
If the error occurs again after restarting the device or after a reset to factory
settings, then contact Bender Service.
3.2.6 Assignment of the alarm relays K1/K2
The messages "device error", "insulation fault", "insulation impedance fault",
"undervoltage/overvoltage fault", "device test" or "device start with alarm"
can be assigned to the alarm relays via the "out" menu. An insulation fault is
indicated by the messages "+R1", "-R1", "+R2" and "-R2". Messages "+R1" and
"+R2" can be assigned to indicate an insulation fault on conductor L1/+ and
the messages "-R1" and "-R2" could indicate an insulation fault on conductor

Function
20 isoMIL425_D00203_03_M_XXEN/03.2019
L2/-. If an assignment is not possible, for example in the event of a symmetri-
cal insulation fault, the message corresponding to "+" and "- " are shown to-
gether.
The message "test" indicates a self test.
The message "S.AL" indicates a so-called "device start with alarm". After con-
necting to the supply voltage Usand setting the parameter value to
"S.AL = on", the ISOMETER® starts with the insulation measurement value
RF= 0  and ZF= 0  in Z mode and displays all activated alarms. The alarms
will be cleared only when the measured values are up-to-date and no
thresholds are exceeded. In the factory setting "S.AL = off", the ISOMETER®
starts without an alarm.
It is recommended that the value set for the parameter "S.AL" is identical for
both relays.
3.2.7 Measuring and response times
The measuring time is the period essential for the detection of the measuring
value. The measuring time is reflected in the operating time tae .
In R mode, the measuring time for the insulation resistance value is mainly de-
termined by the required measuring pulse duration, which depends on the in-
sulation resistance RFand system leakage capacitance Ceof the system to be
monitored. The measuring pulse is produced by the measuring pulse genera-
tor integrated in the ISOMETER® . The measuring times for Ce, UL1e, UL2e and
R% are synchronous. System disturbances may lead to extended measuring
times. In contrast, the time for the system voltage measurement Unis inde-
pendent and considerably shorter.
In Z mode a fixed and short measuring pulse time is applied, leading to a short
measuring time for all measured values.
Total response time tan
The total response time tan is the sum of the operating time tae and the
on-delay time ton.