Bender ISOMETER isoGEN423 User manual

Manual ENisoGEN423_D00221_03_M_XXEN / 04.2021
ISOMETER® isoGEN423
Insulation monitoring device for unearthed AC, AC/DC and DC systems
(IT systems) up to 3(N)AC, AC 400 V, DC 400 V
Suitable for the application of generators acc. to
standard DIN VDE 0100-551
Software version: D0494 V1.xx

2 isoGEN423_D00221_03_M_XXEN / 04.2021
Service and support for Bender products
First-level support
Technical support
Carl-Benz-Strasse 8 • 35305 Grünberg • Germany
Telephone: [phone]
0700BenderHelp *
Fax: [phone]
E-mail: [e-mail]
Available on 365 days from 7.00 a.m. to 8.00 p.m. (MEZ/UTC +1)
* Landline German Telekom: Mon-Fri from 9.00 a.m. to 6 p.m.: 6.3 cents/30 sec.; remaining time: 6.3
cents/min.
Mobile phone: higher, depending on mobile phone tariff
Repair service
Repair, calibration and replacement service
Londorfer Strasse 65 • 35305 Grünberg • Germany
Telephone: [phone] (technical issues) or
[phone], -785 (commercial issues)
Fax: [phone]
E-mail: [e-mail]
Field service
On-site service
Telephone: [phone], -762 (technical issues) or
[phone] (commercial issues)
Fax: [phone]
E-mail: fi[e-mail]
Mon-Thu 7.00 a.m. to 4.00 p.m., Fri 7.00 a.m. to 1 p.m. (MEZ/UTC +1)

isoGEN423_D00221_03_M_XXEN / 04.2021 3
ISOMETER® isoGEN423
Table of Contents
1 General instructions .........................................................................5
1.1 How to use this manual..............................................................................................5
1.2 Indication of important instructions and information ...................................5
1.2.1 Signs and symbols ........................................................................................................5
1.3 Training courses and seminars.................................................................................5
1.4 Delivery conditions.......................................................................................................5
1.5 Inspection, transport and storage ..........................................................................6
1.6 Warranty and liability...................................................................................................6
1.7 Disposal of Bender devices........................................................................................6
1.8 Safety .................................................................................................................................7
2 Function...............................................................................................8
2.1 Intended use...................................................................................................................8
2.2 Device features ..............................................................................................................8
2.3 Functional description ................................................................................................9
2.3.1 GEn mode ........................................................................................................................9
2.3.2 dc mode............................................................................................................................9
2.3.3 General measuring functions ...................................................................................9
2.3.4 Isolation from the system to be monitored ..................................................... 10
2.3.5 Monitoring the insulation resistance.................................................................. 10
2.3.6 Undervoltage/overvoltage monitoring ............................................................. 10
2.3.7 Self test/error codes.................................................................................................. 10
2.3.8 Malfunction ..................................................................................................................12
2.3.9 Signalling assignment of the alarm relays K1/K2........................................... 12
2.3.10 Measuring and response times............................................................................. 12
2.3.11 Password protection (on, OFF).............................................................................. 13
2.3.12 Factory settings FAC .................................................................................................13
2.3.13 External, combined test or reset button T/R.................................................... 14
2.3.14 Fault memory ..............................................................................................................14
2.3.15 History memory HiS .................................................................................................. 14
2.3.16 Interface/protocols.................................................................................................... 15
3 Installation, connection and commissioning ............................ 16
3.1 Dimensions................................................................................................................... 16
3.2 Mounting....................................................................................................................... 16
3.3 Wiring diagram ...........................................................................................................17
3.4 Commissioning ...........................................................................................................18

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4 Operation of the device................................................................. 19
4.1 Display elements........................................................................................................ 20
4.2 Menu overview ...........................................................................................................21
4.3 Menu „AL“ .....................................................................................................................22
4.3.1 Response value setting............................................................................................ 22
4.4 Menu „out“ ...................................................................................................................22
4.4.1 Configuration of the relay operating mode..................................................... 22
4.4.2 Relay alarm assignment „r1“ and „r2“ and LED assignment ......................23
4.4.3 Fault memory configuration..................................................................................24
4.4.4 Interface configuration ............................................................................................24
4.5 Menu „t“......................................................................................................................... 24
4.5.1 Time configuration.................................................................................................... 24
4.6 Menu „SEt“.................................................................................................................... 25
4.6.1 Function configuration ............................................................................................25
4.7 Measuring value display and history memory................................................26
5 Data access using the BMS protocol ........................................... 27
6 Data access using the Modbus RTU protocol............................ 28
6.1 Reading out the Modbus register from the ISOMETER®..............................28
6.1.1 Command of the Master to the ISOMETER®..................................................... 28
6.1.2 Answer of the ISOMETER® to the Master........................................................... 28
6.2 Write Modbus register (parameter setting)......................................................29
6.2.1 Command of the Master to the ISOMETER®..................................................... 29
6.2.2 ISOMETER® answer to the Master ........................................................................ 29
6.3 Exception code ...........................................................................................................30
6.3.1 Structure of the exception code........................................................................... 30
7 Modbus register assignment of the ISOMETER® ...................... 31
7.1 Device-specific data type of the ISOMETER® ................................................... 34
7.1.1 Device name ................................................................................................................34
7.1.2 Measuring values .......................................................................................................34
7.1.3 Alarm assignment of the relays ............................................................................ 37
7.2 Channel descriptions................................................................................................ 38
8 IsoData data string ......................................................................... 40
9 Technical data.................................................................................. 41
9.1 Tabular presentation.................................................................................................41
9.2 Standards, approvals and certifications.............................................................43
9.3 Ordering information ...............................................................................................44
9.4 Document revision history ..................................................................................... 44

isoGEN423_D00221_03_M_XXEN / 04.2021 5
ISOMETER® isoGEN423
1 General instructions
1.1 How to use this manual
This manual is intended for qualified personnel working in electrical engineering and elec
tronics! Part of the device documentation, in addition to this manual, is the enclosed
“Safety instructions for Bender products”.
Read the manual before installing, connecting and commissioning the device.
Always keep the manual within easy reach for future reference.
1.2 Indication of important instructions and information
I Danger! Indicates a high risk of danger that will result in death or serious injury if
not avoided.
I Warning! Indicates a medium risk of danger that can lead to death or serious injury, if
not avoided.
I Caution! Indicates a low-level risk that can result in minor or moderate
injury or damage to property if not avoided.
i
Information can help to optimise the use of the product.
1.2.1 Signs and symbols
Disposal Temperature range protect from dust
protect from wetness Recycling RoHS
guidelines
1.3 Training courses and seminars
www.bender.de > Know-how-> Seminars.
1.4 Delivery conditions
The conditions of sale and delivery set out by Bender apply. These can be obtained from Bender
in printed or electronic format.
The following applies to software products:
“Software clause in respect of the licensing of standard software as part of de-
liveries, modifications and changes to general delivery conditions for products
and services in the electrical industry.”
Die Elektroindustrie

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General instructions
1.5 Inspection, transport and storage
Check the shipping and device packaging for transport damage and scope of delivery. The follow-
ing must be observed when storing the devices:
1.6 Warranty and liability
Warranty and liability claims in the event of injury to persons or damage to property are excluded
in case of:
• 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, com-
missioning, operation and maintenance of the device.
• Unauthorised changes to the device made by parties other than the manufacturer.
• Non-observance of technical data.
• Repairs carried out incorrectly.
• Use of accessories and spare parts not recommended by Bender.
• Catastrophes caused by external influences and force majeure.
• Mounting and installation with device combinations not recommended by the manufac-
turer.
This operating manual and the enclosed safety instructions must be observed by all persons
working with the device. Furthermore, the rules and regulations that apply for accident preven-
tion at the place of use must be observed.
1.7 Disposal of Bender devices
Abide by the national regulations and laws governing the disposal of this device.
For more information on the disposal of Bender devices, refer to
www.bender.de -> Service & support.

isoGEN423_D00221_03_M_XXEN / 04.2021 7
ISOMETER® isoGEN423
1.8 Safety
If the device is used outside the Federal Republic of Germany, the applicable local standards and
regulations must be complied with. In Europe, the European standard EN 50110 applies.
I Danger! Risk of electrocution due to electric shock!
Touching live parts of the system carries the risk of:
• A fatal 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-ener-
gised. The rules for working on electrical systems must be observed.

8 isoGEN423_D00221_03_M_XXEN / 04.2021
Function
2 Function
2.1 Intended use
The ISOMETER® monitors the insulation resistance RFof unearthed AC, AC/DC and DC systems
(IT systems) with nominal system voltages of 3(N)AC, AC/DC 0…400 V or DC 0…400 V. The
maximum permissible system leakage capacitance Ceis 5 µF. DC components existing in
AC systems do not influence the operating characteristics, when a minimum load current of
DC 10 mA flows. A separate supply voltage Usallows de-energised systems to be monitored, too.
In order to meet the requirements of applicable standards, customised parameter settings must
be made on the equipment in order to adapt it to local equipment and operating conditions.
Please heed the limits of the range of application indicated in the technical data.
Any use other than that described in this manual is regarded as improper.
i
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.
i
If the ISOMETER® is installed inside a control cabinet, the insulation fault message must
be audible and/or visible to attract attention.
2.2 Device features
• Monitoring the insulation resistance RFfor unearthed AC/DC systems
• Measurement of the nominal system voltage Un(True RMS) with undervoltage and
overvoltage detection
• Measurement of residual voltages to earth (L1+/PE and L2-/PE)
• Two operating modes: GEn and dc
• Automatic adaptation to the system leakage capacitance Ceup to 5 μF
• Selectable start-up delay, response delay and delay on release
• Two separately adjustable response value ranges of 5…200 kΩ (Alarm 1, Alarm 2)
• Alarm signalling via LEDs („AL1“, „AL2“), a display and alarm relays („K1“, „K2“)
• Automatic device self test with connection monitoring
• Selectable N/C or N/O relay operation
• 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

isoGEN423_D00221_03_M_XXEN / 04.2021 9
ISOMETER® isoGEN423
2.3 Functional description
The ISOMETER® measures the insulation resistance RF. It features two operating modes: „GEn“ and
„DC“. The two operating modes can be switched in the menu „SEt“.
2.3.1 GEn mode
The GEn mode is used in AC/DC or also in DC systems. The device complies with the maximum
response time ≤ 1 s for Ce≤ 1 µF and RF≤ Ran/2.
2.3.2 dc mode
The dc mode is only used in DC systems. In this mode, the device complies with the maximum
response time of ≤ 1 s for Ce≤ 2 µF and RF≤ Ran/2 in the event of asymmetrical insulation faults. In
case of symmetrical insulation faults, response times of ≤ 10 s for Ce≤ 5 µF and RF≤ Ran/2 are
complied with. The system leakage capacitance Ceis also measured in this mode.
2.3.3 General measuring functions
The ISOMETER® measures the RMS value of the nominal system voltage Unbetween L1/+ und L2/-
as well as the residual voltages UL1e (between L1/+ and earth) and UL2e (between L2/- and earth).
When coupled to a DC system, the ISOMETER® determines from a minimum value of the nominal
system voltage the faulty conductor L1/+ or L2/-, which shows the distribution of the insulation
resistance between conductors L1/+ and L2/-. The distribution is indicated by a „+“ or „-“ sign
preceding the insulation resistance measurement. The value range of the faulty conductor
is ±100 %:
Indication Meaning
-100 % One-sided fault on conductor L2/-
0 % Symmetrical fault
+100 % One-sided fault on conductor L1/+
The partial resistances can be calculated from the total insulation resistance RFand the faulty
conductor (R %) using the following formula:
Fault on conductor L1/+ -> RL1F = (200 % * RF)/(100 % + R%)
Fault on conductor L2/- -> RL2F = (200 % * RF)/(100 % – R%)
When the ISOMETER® is coupled to an AC system, the fault location can only be determined in a
connected DC system and the faulty conductor is detected either on L1/+ (+100 %) or
L2/- (-100 %). Calculating the fault distribution is not possible in this case.
It is possible to assign the detected fault or the faulty conductor to an alarm relay via the menu. If
the values RFor Unviolate the response values activated in the „AL“ menu, this will be indicated by
the LEDs and relays „K1“ and „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“ is activated.

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Function
If the values RFor Undo not violate 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 is
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.
2.3.4 Isolation from the system to be monitored
If the device has no supply voltage Usor is in stop mode, it decouples terminals „L1/+“ and „L2/-“
internally from the IT system being monitored. In this case, an insulation measurement up to
DC 500 V can be carried out using an insulation tester.
2.3.5 Monitoring the insulation resistance
The two parameters that monitor the insulation resistance, „R1“ and „R2“, can be found in the
menu „AL“ (see table on page 22). The value R1 can only be set higher than the value R2. 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 22),
the alarm will be cleared.
2.3.6 Undervoltage/overvoltage monitoring
In the menu „AL“ (see page 22), the parameters („U <“ and „U >“) for monitoring the nominal
system voltage Uncan be activated or deactivated. The maximum undervoltage value is limited
by the overvoltage value.
The RMS value of the nominal system voltage Unis monitored. If the nominal system voltage Un
reaches, falls below or exceeds the limit values („U <“ or „U >“), an alarm will be signalled. If the
maximum permissible nominal system voltage Unset 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 hysteresis (see page 22) are no longer violated.
2.3.7 Self test/error codes
The integrated self test function checks the function of the insulation monitoring device, and
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 (menu „out“, page 22) eingestellt werden. 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.

isoGEN423_D00221_03_M_XXEN / 04.2021 11
ISOMETER® isoGEN423
Error codes
If, contrary to expectations, a device error should occur, error codes will appear on the display.
Some of these are described below:
Error code Description
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 fault system
The internal resistance of the system is too high or the connection „L1/+“ or„L2/-“ to the system is
interrupted. The terminals„L1/+“ and„L2/-“ are connected false.
Action:
Check connection, eliminate error.The error code will be erased automatically once the error has been
eliminated.
E.03 The terminals„L1/+“ and„L2/-“ are connected to the DC system to be monitored with reversed polarity.
Detection from Un< -30VDC
E.05
Measurement technique error:
Due to system interferences or a device error, the insulation measuring value is no longer updated.The
pre- and main alarm are set for the insulation measuring value simultaneously.
Calibration invalid after software update:
In case of a software update,„E.05“ appears together with„E.08“ if the new software is no longer
compatible with the calibration of the device. Either the previous software version must be installed or the
device must be calibrated new in the factory.
E.07 The permissible system leakage capacitance Ceaccording to the datasheet is exceeded (only in„dc“ and
„CHd“ settings).
E.08
A calibration error was detected during the device test.
Action:
If the error continues to exist after checking the device connections, there is an error inside the device.
Internal device errors „E.xx“ can be caused by external disturbances or internal 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 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.

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Function
Automatic self test
The device runs a self test after connecting the supply voltage Usand later every 24 h
(selectable at „Menu „t““ on page 24 : off, 1 h, 24 h).
Manual self test
By pressing the external test/reset button or the test button „T“ on the device for > 1.5 s, a self
test is started. While holding down the test button „T“, all device-relevant display elements
appear on the display.
2.3.8 Malfunction
In addition to the described self test, several functions in the insulation monitoring device are
continuously checked during operation. If a fault is detected, 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 restoring the factory settings, please
contact Bender Service.
2.3.9 Signalling assignment of the alarm relays K1/K2
The notifications for „device error“, „insulation fault“, „insulation impedance fault“,
„undervoltage/overvoltage fault“, „device test“ and „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“ indicate an insulation fault assigned to conductor
L1/+, and the messages „-R1“ and „-R2“ indicate an insulation fault assigned to conductor L2/-.
The message „test“ indicates a self test.
The message „S.AL“ indicates a so-called „device start with alarm“.
After connecting to the supply voltage Usand setting the parameter value to „S.AL = on“, the
ISOMETER® starts with the insulation measured value RF= 0 Ω and sets 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 „S.AL“ parameter value is identical for both relays.
2.3.10 Measuring and response times
Operating time tae
The operating time tae is the time required by the ISOMETER® to determine the measured value.
For the insulation measuring value RF, the system leakage capacitance Ce, the residual voltages
UL1e and UL2e and the fault location R%, it is dependent on the insulation resistance RFand the
system leakage capacitance Ce. System interferences can lead to longer operating times. The
measuring time of the nominal system voltage Unis independent of this and significantly shorter.

isoGEN423_D00221_03_M_XXEN / 04.2021 13
ISOMETER® isoGEN423
Response delay ton
The response delay ton can be set uniformly for all messages in the „t“ menu using the parameter
„ton“, whereby each alarm message specified in the alarm assignment has its own timer for ton.
This delay time can be used for interference suppression in the case of short measuring times.
An alarm will only be signalled when a threshold value of the respective measuring value is
violated for the period of ton without interruption. Every time the threshold value is violated
within the time ton, the response delay „ton“ restarts once again.
Total response time tan
The total response time tan is the sum of the operating time tae and the response delay time ton.
Delay on release toff
The delay on release toff can be set uniformly for all messages in the „t“ menu using the parameter
„toff“, whereby each alarm message specified in the alarm assignment has its own timer for toff.
An alarm will continuously be signalled until the threshold value of the respective measured
value is not violated (including hysteresis) for the period of toff without interruption.
Each time the threshold value is not violated for the period of toff, the delay on release „toff“
restarts once again.
Start-up delay t
After connection to the supply voltage USthe alarm indication for the preset time (0…10 s) in the
parameter „t“ is suppressed.
2.3.11 Password protection (on, OFF)
If password protection has been activated (on), settings can only be made subject to the correct
password being entered (0...999).
2.3.12 Factory settings FAC
Activating the factory setting will reset all modified settings, with the exception of the interface
parameters, to the default upon delivery.

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Function
2.3.13 External, combined test or reset button T/R
Reset = Press the external button < 1.5 s
Reset followed by a test = Press the external button > 1.5 s
Stop measuring function = Press and hold the external button
i
When the measuring function is stopped, the display shows „STP“.
The stop function can also be triggered via an interface command and in this case it can only be
reset via the interface.
Only one ISOMETER® may be controlled via an external test/reset button.
A galvanic parallel connection of several test or reset inputs for testing multiple insulation
monitoring devices is not allowed.
2.3.14 Fault memory
The fault memory can be activated or deactivated with the parameter „M“ in the „out“ menu.
When the fault memory is activated, all pending alarm messages of the LEDs and relays remain
available until they are deleted by using the reset button (internal/external) or the supply voltage
Usis turned off.
2.3.15 History memory HiS
When the first error occurs after clearing the history memory, all measured values (that are ticked
in the table on page 26)are saved in the history memory. This data can be read out using the
„HiS“ menu item. In order to be able to record a new data record, the history memory must first
be cleared via the menu using „Clr“.

isoGEN423_D00221_03_M_XXEN / 04.2021 15
ISOMETER® isoGEN423
2.3.16 Interface/protocols
The ISOMETER® uses the serial hardware interface RS-485 with the following protocols:
• BMS
The BMS protocol is an essential component of the Bender measuring device interface
(BMS bus protocol). Data transmission takes place with ASCII characters.
• Modbus RTU
Modbus RTU is an application layer messaging protocol and it provides Master/Slave
communication between devices that are connected altogether via bus systems and
networks. Modbus RTU messages have a 16-bit CRC (Cyclic Redundant Checksum),
which guarantees reliability.
• IsoData
The ISOMETER® continuously sends an ASCII data string with a cycle of approximately
1 s. Communication with the ISOMETER® within this mode is not possible and no
additional transmitter may be connected to the RS-485 bus cable. The ASCII data string
for the ISOMETER® is described on page 40.
The parameter address, baud rate and parity for the interface protocols are configured in the
„out“ menu.
i
With „Adr = 0“, the menu entries baud rate and parity are not shown in the menu and
the IsoData protocol is activated.
With a valid bus address (i.e. not equal to 0), the menu item „baud rate“ is displayed in
the menu. The parameter value „---“ for the baud rate indicates the activated BMS
protocol. In this case, the baud rate for the BMS protocol is set to 9600 baud. If the baud
rate is set unequal to „---“, the Modbus protocol with configurable baud rate is activated.
i
The IsoData protocol can be cancelled by sending the command „Adr3“ during a
non-transmission period of isoGEN423.

16 isoGEN423_D00221_03_M_XXEN / 04.2021
Installation, connection and commissioning
3 Installation, connection and commissioning
3.1 Dimensions
Fig. 3–1 All dimensions in mm
3.2 Mounting
Variant A: DIN rail mounting Variant B: Screw mounting
The front plate cover can be opened at the lower part marked with an arrow.
93
45
67,5
36
31,1
47,5
74,5
2
2
1.
2.
3. Click!
&2 x
1 x
100 107
Click
M4
M4
!

isoGEN423_D00221_03_M_XXEN / 04.2021 17
ISOMETER® isoGEN423
3.3 Wiring diagram
For details about the conductor cross sections required for wiring, refer to the technical data on page 41.
Legend
Terminal Connections
A1, A2 Connection to the supply voltage Usvia fuse (line protection):
If supplied from an IT system, both lines have to be protected by a fuse.*
E, KE Connect each terminal separately to PE:
The same wire cross section as for„A1“,„A2“ is to be used.
L1/+, L2/– Connection to the IT system to be monitored
T/R Connection for the external combined test and reset button
11, 14 Connection to alarm relay„K1“
11, 24 Connection to alarm relay„K2“
A, B RS-485 communication interface with connectable terminating resistance
Example: Connection of a BMS-Ethernet-Gateway COM465IP
i
* For UL applications:
Only use 60/75 °C copper lines!
For UL and CSA applications, it is mandatory to use 5 A fuses for the protection of the
supply voltage Us.
US
L1/+
KE A1 A2
Test / Reset
14 24 11
K1 K2
T/R
L2/
E
L1/+
L2/-
PE
L3
COM465IP
RS-485
AB
R
ON AL1AL2 k
TR
MENU
R
on
o
14
24
11
A
T/R
B
L1/+
L2/-
E
KE
A2
A1

18 isoGEN423_D00221_03_M_XXEN / 04.2021
Installation, connection and commissioning
3.4 Commissioning
1. Check that the ISOMETER® is properly connected to the system to be monitored.
2. Connect the supply voltage Usto the ISOMETER®.
The device carries out a calibration, a self test and adjusts itself to the IT system to be
monitored. When high system leakage capacitances are involved, this procedure may
take up to 30 s. The standard display then appears showing the present insulation
resistance, e.g.:
The pulse symbol signals an error-free update of the resistance and capacitance measuring
values. If the measuring value cannot be updated due to disturbances, the pulse symbol will be
blanked.
The voltage of the IT system to be monitored can also be selected as standard display.
By selecting the measured value display UL1L2 with the buttons and the following acceptance
with the button, the standard display is changing to UL1L2.
3. Start a manual self test by pressing the test button „T“. Whilst the test button is pressed
and held down, all display elements available for this device are shown. During the test,
the „tES“ symbol flashes. Any internal malfunctions detected are shown on the display
as error codes (see page 10). The alarm relays are not checked during the test
(factory setting). The setting can be changed in the „out“ menu, so that the relays switch
to the alarm state during the manual self test.
4. Check factory setting for suitability.
Are the settings suitable for the installation to be monitored?
The list of factory settings are shown in the tables from page 22.
5. Check the function using a genuine insulation fault.
Check the ISOMETER® in the system being monitored against earth, e.g. via a suitable
resistance.

isoGEN423_D00221_03_M_XXEN / 04.2021 19
ISOMETER® isoGEN423
4 Operation of the device
The menu structure is illustrated schematically on the following pages.
After pressing the „MENU“ button for > 1.5 s, the first menu item „AL“ appears.
Use and (Enter) buttons for navigation and settings.
Up and down button:
• to navigate up or down in the menu settings
• increasing or decreasing values
MENU
Pressing the MENU/Enter button for more than 1.5 s:
• Starts menu mode
or
• when the device already is in menu mode:
Exit menu item (Esc).
Any recent changes will not be stored.
Pressing the MENU/Enter button for less than 1.5 s:
• Confirms menu selection.
or
• confirms modified value.
i
The areas of the display that can be configured flash!

20 isoGEN423_D00221_03_M_XXEN / 04.2021
Operation of the device
4.1 Display elements
Device front/display Function
AL1 AL2
ON
AL1
AL2
green - on
yellow - alarm
yellow - alarm
Assignment according to table on page 23
T
Up button
Test button ( press > 1.5 s)
By pressing and holding the test button, the display elements are
indicated.
R
Down button
Reset button (press > 1.5 s)
MENU
ENTER
MENU button (press > 1.5 s)
+
test onoff MAdr
L1L2 C
<
>
s
kM %
Fµ
{
{
{
{
12 3
4
567
8
{
9
{
10
1
U: Nominal system voltage Un
R: Insulation resistance RF
C: System leakage capacitance Ce
2Monitored conductor
3
= :Voltage type DC
: Error-free measured value update
~ :Voltage type AC
4Measured values and units
5Password protection is activated.
6In the menu mode, the operating mode of the respective alarm relay
is displayed.
7Communication interface
With measured value: isoData operation
8The fault memory is activated.
9Condition symbols
10 Identification for response values and response value violation