Bender ISOMETER isoMIL425HV User manual

Manual EN
ISOMETER® isoMIL425HV
Insulation monitoring device with coupling device AGH421
for unearthed AC, AC/ C and C systems
for military applications up to 3(N)AC, AC 690 V, C 1000 V
Software version: 460 V1.xx
isoMIL425HV_D00204_06_M_XXEN/08.2023

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ISOMETER® isoMIL425HV
Table of contents
1General information 5
1.1 How to use the manual.................................................................................................................................5
1.2 Indication of important instructions and information.......................................................................5
1.3 Signs and symbols...........................................................................................................................................5
1.4 Service and Support....................................................................................................................................... 5
1.5 Training courses and seminars...................................................................................................................6
1.6 elivery conditions......................................................................................................................................... 6
1.7 Inspection, transport and storage.............................................................................................................6
1.8 Warranty and liability.....................................................................................................................................6
1.9 isposal of Bender devices..........................................................................................................................7
1.10 Safety.................................................................................................................................................................... 7
2Function 8
2.1 Intended use......................................................................................................................................................8
2.2 evice features................................................................................................................................................. 8
2.3 Functional description...................................................................................................................................9
2.3.1 Monitoring the insulation resistance.....................................................................................................10
2.3.2 Undervoltage/overvoltage monitoring................................................................................................ 10
2.3.3 Self test/error codes.....................................................................................................................................10
2.3.4 Malfunction......................................................................................................................................................11
2.3.5 Alarm assignment of the alarm relays K1/K2..................................................................................... 12
2.3.6 Measuring and response times................................................................................................................12
2.3.7 Password protection (on, OFF)................................................................................................................ 12
2.3.8 External stop switch.....................................................................................................................................13
2.3.9 Fault memory..................................................................................................................................................13
2.3.10 History memory HiS..................................................................................................................................... 13
2.3.11 igital interface..............................................................................................................................................13
3Installation, connection and commissioning 15
3.1 imensions...................................................................................................................................................... 15
3.2 Installation........................................................................................................................................................15
3.3 Connection.......................................................................................................................................................16
3.4 Commissioning...............................................................................................................................................18
4Operation 19
4.1 Operating and display elements.............................................................................................................19
isoMIL425HV_ 00204_06_M_XXEN/08.2023 3

Table of contents
4.2 Menu overview...............................................................................................................................................21
4.3 isplaying measured values..................................................................................................................... 22
4.4 Setting the response values (AL)............................................................................................................ 23
4.4.1 Setting the response values for insulation monitoring.................................................................. 23
4.4.2 Setting the response values for undervoltage and overvoltage.................................................23
4.4.3 Response values overview.........................................................................................................................23
4.5 Configuring fault memory, alarm relays, and interfaces (out)......................................................23
4.5.1 Configuring the relays.................................................................................................................................24
4.5.2 Assigning the alarm messages to the relays...................................................................................... 24
4.5.3 Activating or deactivating fault memory.............................................................................................25
4.5.4 Configuring interface...................................................................................................................................25
4.6 Setting delay times and self test cycles (t).......................................................................................... 25
4.7 Setting device control parameters (SEt)...............................................................................................26
4.8 Reset to factory settings.............................................................................................................................26
4.9 Showing and deleting the history memory........................................................................................26
4.10 Querying software version (InF).............................................................................................................. 26
5Data access via RS-485 interface 27
5.1 ata access using the BMS protocol..................................................................................................... 27
5.2 ata access using the Modbus RTU protocol.................................................................................... 27
5.2.1 Reading out the Modbus register from the ISOMETER®.................................................................27
5.2.2 Writing the Modbus register (parameter setting).............................................................................28
5.2.3 Exception code...............................................................................................................................................29
5.3 Modbus register assignment.................................................................................................................... 30
5.3.1 Modbus measured value registers......................................................................................................... 30
5.3.2 Modbus parameter register...................................................................................................................... 33
5.4 Iso ata data string....................................................................................................................................... 37
6Technical data 38
6.1 Technical data isoMIL425HV.....................................................................................................................38
6.2 Technical data AGH421...............................................................................................................................41
6.3 Connection (for ISOMETER® and AGH)..................................................................................................43
6.4 Standards and certifications..................................................................................................................... 44
6.5 Ordering data..................................................................................................................................................44
6.6 Change log.......................................................................................................................................................45
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ISOMETER® isoMIL425HV
1 General information
1 1 How to use the manual
ADVICE
This manual is intended for qualified personnel working in electrical engineering and electronics!
Part of the device documentation in addition to this manual is the enclosed supplement "Safety
instructions for Bender products".
ADVICE
Read the operating manual before mounting, connecting and commissioning the device. Keep the
manual within easy reach for future reference.
1 2 Indication of important instructions and information
DANGER
Indicates a high risk of danger that will result in death or serious injury if not avoided.
WARNING
Indicates a medium risk of danger that can lead to death or serious injury if not avoided.
CAUTION
Indicates a low-level risk that can result in minor or moderate injury or damage to property if not
avoided.
ADVICE
Indicates important facts that do not result in immediate injuries. They can lead to malfunctions if the
device is handled incorrectly.
Information can help to optimise the use of the product.
1 3 Signs and symbols
isposal Protect from moisture Protect from dust
Temperature range Recycling RoHS directives
1 4 Service and Support
Information and contact details about customer service, repair service or field service for Bender devices are
available on the following website: Fast assistance | Bender GmbH & Co. KG.
isoMIL425HV_ 00204_06_M_XXEN/08.2023 5

General information
1 5 Training courses and seminars
Regular face-to-face or online seminars for customers and other interested parties:
www.bender.de > know-how > seminars.
1 6 Delivery conditions
The conditions of sale and delivery set out by Bender GmbH & Co. KG apply. These can be obtained in printed
or electronic format.
The following applies to software products:
Die 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 industry’
1 7 Inspection, transport and storage
Check the shipping and device packaging for transport damage and scope of delivery. In the event of
complaints, the company must be notified immediately, see "www.bender.de > service & support.".
The following must be observed when storing the devices:
1 8 Warranty and liability
Warranty and liability claims for personal injury and property damage are excluded in the 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, commissioning, 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.
•The use of accessories or spare parts that are not provided, approved or recommended by the
manufacturer.
•Catastrophes caused by external influences and force majeure.
•Mounting and installation with device combinations not approved or recommended by the manufacturer.
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 prevention at the place of use must be
observed.
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ISOMETER® isoMIL425HV
1 9 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.
1 10 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.
DANGER Risk of fatal injury due to electric shock!
Touching live parts of the system carries the risk of:
•Risk of electrocution due to electric shock
•amage to the electrical installation
•estruction of the device
Before installing the device and before working on its connections, make sure that the installation
has been de-energised. The rules for working on electrical systems must be observed.
isoMIL425HV_ 00204_06_M_XXEN/08.2023 7

Function
2 Function
2 1 Intended use
The ISOMETER® of the isoMIL425HV series monitors the insulation resistance RF of unearthed AC/ C main
circuits (IT systems) with nominal system voltages of 3(N)AC, AC/ C 0…690 V or C 0…1000 V, 15…460 Hz.
C components existing in 3(N)AC, AC/ C systems do not influence the operating characteristics when a
minimum load current of C 10 mA flows. The separate supply voltage Us allows de-energised systems to be
monitored as well.
The maximum permissible system leakage capacitance is 700 μF.
The ISOMETER® is always used in conjunction with the coupling device AGH421.
In order to meet the requirements of the 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 other use or a use that goes beyond this constitutes improper use.
To ensure that the ISOM T R® functions correctly, an internal resistance of ≤ 1 kΩ must exist between L1/+
and L2/– via the source (e.g. PSU) or the load.
If the ISOM T R® is installed inside a control cabinet, the insulation fault message must be audible and/or
visible to attract attention.
2 2 Device features
•Monitoring of the insulation resistance RF for unearthed 3(N)AC, AC and C systems with galvanically
connected rectifiers or frequency converters
•Measuring the system voltage Un (RMS) with undervoltage/overvoltage detection
•Measuring the C residual voltages UL1e (between L1/+ and earth) and UL2e (between L2/– and earth)
•Selectable start-up delay, response delay and delay on release
•Alarm output via LE s ('AL1', 'AL2'), 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 LC display
•Activatable fault memory
•Automatic adaptation to the system leakage capacitance Ce up to 700 μF
•Two separately adjustable response value ranges from 1…500 kΩ (prewarning, alarm)
•RS-485 (galvanically isolated) including the following protocols:
– BMS (Bender measuring device interface) for the data exchange with other Bender devices
– Modbus RTU
– Iso ata (for continuous data output)
•Password protection against unauthorised changing of parameters
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ISOMETER® isoMIL425HV
2 3 Functional description
The ISOMETER® measures the insulation resistance RF and the system leakage capacitance Ce between the
system to be monitored (L1/+, L2/–) and earth (PE). The RMS value of the nominal system voltage Un between
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® determines the faulty conductor 'R %',
which shows the distribution of the insulation resistance between conductors L1/+ and L2/–. The distribution
is indicated by a positive or negative sign preceding the insulation resistance measurement. The value range of
the faulty conductor is ±100 %:
Indication Meaning
–100 % one-sided fault at conductor L2/–
0 % symmetrical fault
+100 % one-sided fault at conductor L1/+
The partial resistances can be calculated from the total insulation resistance RF and the faulty conductor 'R %'
using the following formula:
Fault at conductor L1/+: RL1F = (200 % x RF) / (100 % + R %)
Fault at conductor L2/–: RL2F = (200 % x RF) / (100 % – R %)
Also from a minimum value of the nominal system voltage, the ISOMETER® determines 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 RF and Ce relation
that varies considerably.
The detected fault is assignable to an alarm relay via the menu. If the values RF or Un violate the response
values activated in the 'AL' menu, this will be indicated by the LE s and relays 'K1' and 'K2' according to the
signalling assignment set in the 'out' menu. In addition, the menu offers the setting of the relay operation (n.c./
n.o.) and the activation of the fault memory 'M'.
If the values RF or Un do 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 LE s 'AL1'/'AL2'
stop lighting. If the fault memory is activated, the alarm relays remain in alarm position and the LE s are lit
until the reset key 'R' is pressed or the supply voltage Us is interrupted.
The ISOMETER® features a stop switch. When the stop switch is closed, the ISOMETER® is in operation. If the
stop switch is opened, the ISOMETER® enters stop mode, i.e. the coupling L1/+ and L2/– is connected with
high resistance (approx. 20 MΩ) to the system to be monitored. In stop mode, if the memory function 'M' is
activated (reset function), the fault memory is cleared. The stop function can also be triggered via an interface
command. In this case it can only be reset via the interface. When starting the device or leaving the stop mode,
no device test is run.
The device function can be checked with the test button 'T'.
Parameters are assigned to the device via the LC 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.
isoMIL425HV_ 00204_06_M_XXEN/08.2023 9

Function
2 3 1 Monitoring the insulation resistance
The insulation resistance RF is monitored by means of the parameters 'R1' (prewarning) and 'R2' (alarm) (see
chapter 4.4). The value 'R1' can only be set higher than the value 'R2'. If the insulation resistance RF reaches or
falls below the activated values 'R1' or 'R2', an alarm message is triggered. If RF exceeds the values 'R1' or 'R2'
plus the hysteresis value, the alarm will be cleared.
2 3 2 Undervoltage/overvoltage monitoring
To monitor the system voltage Un, the two parameters 'U ˂' and 'U ˃' can be enabled in the response-value
menu 'AL' (chapter 4.4). The maximum undervoltage value is limited by the overvoltage value.
The RMS value of the system voltage Un is monitored. If the system voltage Un reaches, falls below, or exceeds
the limit values 'U ˂' and 'U ˃', an alarm will be signalled. If the maximum permissible system voltage Un set
for the ISOMETER® is exceeded, an alarm message will be triggered even if the overvoltage limit value has
been deactivated. The alarm will be deleted when the limit values plus hysteresis (chapter 4.4.1) are no longer
violated.
2 3 3 Self test/error codes
The self test checks the function of the ISOMETER®, and monitors the connection to earth as well as the
connection to the system to be monitored. The alarm relays do not switch during an automatically started self
test. For a self test started manually, the switching of the alarm relays can be set using the parameter 'test' in
the alarm assignment (menu 'out', chapter 4.5.2). uring the test, the display indicates 'tES'.
When malfunctions are detected or connections are missing, the LE s 'ON'/'AL1'/'AL2' flash. The display shows
the respective error codes ('E.xx'), and in the factory setting relay 'K2' switches. The relays can be assigned to a
device error with the parameter 'Err' in the 'out' menu in the alarm assignment.
2 3 3 1 Error codes
In the event of a device error, error codes are shown in the display. Some of these are described below:
Overview of some error codes
Error code Meaning
E.01
PE connection error
The connection of 'E' or 'KE' to earth is interru ted.
Action: Check connection, eliminate error. The error code will be erased automatically once the
error has been eliminated.
E.02
System connection error
The internal resistance of the system is too high or the connection of 'L1/+' or 'L2/–' to the system is
interru ted. The terminals 'L1/+' and 'L2/–' are connected incorrectly.
Action: Check connection, eliminate error. The error code will be erased automatically once the
error has been eliminated.
E.05
Measurement error
Due to system interferences or a device error, the insulation measured value is no longer u dated.
Prewarning and alarm are set for the insulation measured value at the same time.
Calibration invalid after software update
'E.05' a ears together with 'E.08': The software is not com atible to the calibration of the device.
Action: Install the revious software version or have the device calibrated at the factory.
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ISOMETER® isoMIL425HV
Error code Meaning
E.07
Permissible system leakage capacitance Ce e ceeded
The device is not suitable for the resent network leakage ca acitance Ce.
Action: Uninstall the device.
E.08 Calibration error
Action: Check connection, eliminate error. If the error is still resent, there is a device error.
Internal device errors 'E.xx' can be caused by external disturbances or internal hardware errors. If the error
message occurs again after the device has been restarted or after a reset to the factory settings (menu item
'FAC'), the device must be repaired. After the fault has been eliminated, the alarm relays switch back either
automatically or when the reset button is pressed. The self test can take a few minutes.
2 3 3 2 Automatic self test
In the factory setting a self test is carried out when the supply voltage Us is connected and after that every 24 h.
This cycle can be adjusted: off, 1 h, 24 h (see chapter 4.6).
The self test can be suppressed for the device start so that the device can enter the measurement mode more
quickly. To this end, set the parameter 'S.Ct = off' in the menu 'SEt'.
2 3 3 3 Manual self test
The manual self test is started by pressing the external test/reset button or the test button 'T' on the device for
˃ 1.5 s. Holding the test button 'T' also shows all display elements.
2 3 3 4 Connection monitoring
Connection monitoring, activated by the self test, checks the connections of terminals 'E' and 'KE' to the
protective earth conductor (PE). When an error is detected, the message device error ('Err') is signalled and the
error code 'E.01' appears on the display.
The system connection monitoring checks the connection of terminals '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') is signalled and the error code 'E.02' appears on the
display. Since a test of the system connection may take considerable time or even provide incorrect resultsdue
due to system disturbances, the connection monitoring can be switched off using the parameter 'nEt' in the
'SEt' menu.
2 3 4 Malfunction
The device checks some of its functions continuously during operation. If a fault is detected, the device
error ('err') will be signalled, 'E.xx' appears on the display as an identifier for error type xx, and the LE s
'ON'/'AL1'/'AL2' will flash.
Please contact Bender Service, if the error occurs again after the device has been restarted or the factory
settings have been restored.
isoMIL425HV_ 00204_06_M_XXEN/08.2023 11

Function
2 3 5 Alarm assignment of the alarm relays K1/K2
The notifications for 'device error', 'insulation 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 these messages:
•'+R1' and '+R2': insulation fault assigned to conductor L1/+
•'–R1' and '–R2': insulation fault assigned to conductor L2/–
If an assignment to a conductor is not possible, e.g. due to a symmetrical insulation fault, the respective '+' and
'–' messages are set together.
The message 'test' indicates a device test triggered manually via a test button or the communication interface.
2 3 6 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 measured value RF, the system leakage capacitance Ce, the residual voltages UL1e and UL2e as well as
for the faulty conductor 'R%' it depends on the insulation resistance RF and the system leakage capacitance Ce.
System disturbances may lead to extended measuring times. The measuring time of the system voltage Un
is independent of this and significantly shorter.
Response delay ton
The response delay ton is set uniformly for all alarm messages in the 't' menu using the parameter 'ton', while
each alarm message specified in the alarm assignment has its own timer for ton. This delay can be used for
interference suppression in the case of short measuring times.
An alarm message will only be signalled when a limit value of the respective measured value is violated for the
duration of ton. Each time the limit value is violated within the time ton, the response delay 'ton' restarts.
Total response time tan
The total response time tan is the sum of the operating time tae and the response delay ton.
Delay on release toff
The delay on release toff can be set uniformly for all alarm messages using the parameter 'toff', while each alarm
message specified in the alarm assignment has its own timer for toff.
An alarm message will be signalled until the limit value of the respective measured value is no longer violated
(including hysteresis) for the duration of toff without interruption. Each time a limit value is no longer violated
during toff, the delay on release 'toff' restarts.
Start-up delay t
After connecting the supply voltage US, the alarm output is suppressed for the time set in parameter
't' (0…10 s).
2 3 7 Password protection (on, OFF)
If password protection is activated (on), settings can only be made after entering the password (0...999). For its
activation, see chapter 4.7.
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ISOMETER® isoMIL425HV
2 3 8 External stop switch
Functions
•Stop = Press the external switch > 1.5 s.
•Stop measuring function = Press (open) the external switch.
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 with an external stop switch between terminals 'F' and 'Up'. The
connection has to be potential-free since the 'Up' terminal may not be connected to other ISOMETER®s.
2 3 9 Fault memory
Disabled (OFF)
The LE s and relays signal the fault as long as it is detected.
Enabled (ON)
The LE s and relays signal the fault until a reset is performed or the supply voltage Us is disconnected.
2 3 10 History memory HiS
The history memory saves exclusively the measured values for the first fault. The history memory must first be
cleared before new measured values can be saved.
The values checked in the table in section ' isplaying measured values' can be saved.
2 3 11 Digital interface
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).
ata transmission generally makes use of ASCII characters.
•Modbus RTU
Modbus RTU is an application layer messaging protocol, and it provides master/slave communication
between devices that are connected via bus systems and networks. Modbus RTU messages have a 16-bit
CRC (cyclic redundant checksum), which guarantees reliability.
•IsoData
The ISOMETER® sends an ASCII data string with a cycle of approximately 1 second. Communication with
the ISOMETER® in this mode is not possible, and no additional sender may be connected via the RS-485 bus
cable. The ASCII data string for the ISOMETER® is described in chapter 5.4.
The IsoData protocol can be terminated by sending the command 'Adr3' during a transmission pause of
the ISOM T R®.
The parameter address, baud rate and parity for the interface protocols are configured in the 'out' menu.
isoMIL425HV_ 00204_06_M_XXEN/08.2023 13

Function
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.
14 isoMIL425HV_ 00204_06_M_XXEN/08.2023

ISOMETER® isoMIL425HV
3 Installation, connection and commissioning
3 1 Dimensions
36
93
74.5
90 45 70.5
47.5
31.1
Figure: imension diagram (in mm)
3 2 Installation
CAUTION Property damage due to heat
When operating on system voltages Un > 800 V, the housing of the AGH can become hotter than 60 °C.
•Mount AGH with 30 mm lateral clearance to adjacent devices.
Figure: IN rail mounting (left) or screw mounting (right)
isoMIL425HV_ 00204_06_M_XXEN/08.2023 15

Installation, connection and commissioning
3 3 Connection
CAUTION Danger from touching hot surfaces!
If the AGH is operated at mains voltages > 800 V, the temperature of the enclosure may exceed 60 °C.
•o not touch the surfaces of the device after connecting it to the mains voltage.
CAUTION
Only one ISOMETER® may be controlled with an external stop switch between terminals 'F' and
'Up'. The connection has to be potential-free since the 'Up' terminal may not be connected to other
ISOMETER®s.
For details about the required conductor cross sections, refer to chapter 'Technical data'.
Wiring diagram legend:
Terminal Connections
A1, A2 Connection to the su ly voltage Us via fuse:
If su lied from an IT system, both lines have to be rotected by a fuse.*
E, E, KE Connect each terminal se arately to PE:
Use the same wire cross section as for 'A1', 'A2'.
L1/+, L2/– Connection to IT system to be monitored
Up, AK1, GND, AK2 Connect the terminals of the AGH to the corres onding terminals of the ISOMETER®.
T/R Connection for 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 selectable terminating resistance
* For UL applications:
Only use 60/70 °C copper lines!
UL and CSA applications require the supply voltage Us to be protected via 5 A fuses.
16 isoMIL425HV_ 00204_06_M_XXEN/08.2023

ISOMETER® isoMIL425HV
Wiring diagram
Figure: Wiring diagram
isoMIL425HV_ 00204_06_M_XXEN/08.2023 17

Installation, connection and commissioning
3 4 Commissioning
1. Check that the ISOMETER® is properly connected to the system to be monitored
2. Connect supply voltage Us to the ISOMETER®
The device carries out a calibration, a self test and adjusts itself to the IT system to be monitored. With
high system leakage capacitances this process may take up to 4 min. 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 measured values. If
the measured value cannot be updated due to disturbances, the pulse symbol will be blanked.
3. Start a manual self test by pressing the test button 'T' > 1.5 s. While holding the test button all available
display elements are shown. After releasing the button, the test starts and ‘tES’ flashes for the duration of
the test. etected malfunctions are displayed as error codes (see chapter 2.3.3.1).
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 if the settings are suitable for the system being monitored
The list of factory settings is shown in the tables from chapter 4.4.
For networks with a leakage capacitance > 5 μF, the response value Ran1 should be set to a maximum
of 200 kΩ due to the increased measurement tolerance.
5. Check the functionality by a real insulation fault
Use a suitable resistor to check the ISOMETER® against earth in the system being monitored.
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ISOMETER® isoMIL425HV
4 Operation
4 1 Operating and display elements
Device front Operating elements Function
ON Device is running
AL1 Prewarning
Overvoltage
AL2 Alarm
Undervoltage
U and down buttons
– For navigating u or down in the
menu settings.
– For increasing or decreasing values.
TTest button ( ress >1.5s)
RReset button ( ress >1.5s)
Enter button
– Select menu item.
– Save value.
MENU MENU button ( ress >1.5s)
– Starts menu mode.
– Exits menu item without saving
changes.
LE on
LE flashes
isoMIL425HV_ 00204_06_M_XXEN/08.2023 19

Operation
Display Display elements Function
USystem voltage Un
RInsulation resistance RF
CSystem leakage ca acitance Ce
L1 L2 Monitored conductors
Voltage ty e DC
Pulse symbol: error-free measured
value u date
Voltage ty e AC
°C
μ n F Hz
k M Ω %
m V A s
Measured values and units
Password rotection is activated
In the menu mode, the o erating
mode of the res ective alarm relay is
dis layed.
Adr Communication interface with
measured value: isoData o eration
MFault memory is activated
on / off Condition symbols
test Self test is active
>
+
<
Identification for res onse values and
res onse value violation
The display parameters that can be configured flash.
The readability below –25 °C is limited.
Depending on the ISOM T R®'s scope of functions, not all display elements are used.
20 isoMIL425HV_ 00204_06_M_XXEN/08.2023