Bender ISOMETER isoUG425 User manual

EN
Manual
Insulation monitoring device for
earth fault detection in unearthed
DC systems (IT systems) up to 120 V
Software version: D0476 V2.xx
ISOMETER® isoUG425
isoUG425_D00220_02_M_XXEN/05.2018

Bender GmbH & Co. KG
Postbox 1161 • 35301 Grünberg • Germany
Londorfer Straße 65 • 35305 Grünberg • Germany
Tel.: [phone]
Fax: [phone]
E-Mail: [email protected]
Web: www.bender.de
© Bender GmbH & Co. KG
All rights reserved.
Reprinting only with permission
of the publisher.
Subject to change!
Customer service
Service hotline: 0700-BenderHelp (Telephone and Fax)
Carl-Benz-Straße 8 • 35305 Grünberg • Germany
Tel.:[phone]
Fax:[phone]
E-Mail:[email protected]

Table of contents
3isoUG425_D00220_02_M_XXEN/05.2018
1. Important information .................................................................... 5
1.1 How to use this manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Technical support: Service and support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.1 First level support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.2 Repair service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.3 Field service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Training courses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Delivery conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 Inspection, transport and storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.6 Warranty and liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.7 Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. Safety instructions ............................................................................ 7
2.1 General safety instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Work activities on electrical installations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Intended use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Function ............................................................................................. 8
3.1 Device features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Function description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.1 Monitoring the insulation resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.2 Undervoltage/overvoltage monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.3 Self test/error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.4 Malfunction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.5 Signalling assignment of the alarm relays K1/K2 . . . . . . . . . . . . . . . . . 9
3.2.6 Measuring and response times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.7 Password protection (on, OFF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.8 Maximum permissible leakage capacitance . . . . . . . . . . . . . . . . . . . . 10
3.2.9 Factory setting FAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.10 External, combined test or reset button T/R . . . . . . . . . . . . . . . . . . . . 10
3.2.11 Fault memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
3.2.12 History memory HiS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
3.2.13 Interface/protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4. Installation, connection and commissioning ............................12
4.1 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4.2 Wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4.3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
5. Operation of the device .................................................................15
5.1 Display elements in use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
5.2 Menu structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
5.3 "AL" menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
5.3.1 Response value setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
5.4 "out" menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.4.1 Configuration of the relay operating mode . . . . . . . . . . . . . . . . . . . . .17
5.4.2 Relay alarm assignment "r1" and "r2" and LED assignment . . . . . .17
5.4.3 Fault memory configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.4.4 Interface configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.5 "t" menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.5.1 Time configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.6 "SEt" menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.6.1 Function configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.7 Measured value display and history memory. . . . . . . . . . . . . . . . . . . . . . . .18
6. Data access using the BMS protocol ...........................................19

Table of contents
4isoUG425_D00220_02_M_XXEN/05.2018
7. Data access using the Modbus RTU protocol ............................ 20
7.1 Reading out the Modbus register from the ISOMETER®. . . . . . . . . . . . . . 20
7.1.1 Command of the master to the ISOMETER® . . . . . . . . . . . . . . . . . . . . . 20
7.1.2 The ISOMETER® answers the master . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.2 Writing the Modbus register (parameter setting) . . . . . . . . . . . . . . . . . . . 20
7.2.1 Command of the master to the ISOMETER® . . . . . . . . . . . . . . . . . . . . . 20
7.2.2 The ISOMETER® answers the master . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.3 Exception code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.3.1 Structure of the exception code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8. Modbus register assignment of the ISOMETER® ...................... 22
8.1 Device-specific data type of the ISOMETER® . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1.1 Device name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1.2 Measured values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1.2.1 Float = Floating point value of the channels . . . . . . . . . . . . . . 24
8.1.2.2 AT&T = Alarm type and test type (internal/external) . . . . . . . 24
8.1.2.3 R&U = Range and unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.1.3 Alarm assignment of the relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.2 Channel descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9. IsoData data string ......................................................................... 27
10. Technical data ............................................................................... 28
10.1 Tabular representation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
10.2 Standards, approvals and certifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
10.3 Ordering information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
INDEX .................................................................................................... 30

isoUG425_D00220_02_M_XXEN/05.2018
5
Important information
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 manual, we
have used symbols to identify important instructions and information. The meaning of
these symbols is explained below:
This manual is intended for qualified personnel working in
electrical engineering and electronics!
DANGER
This signal word indicates that there is a high risk of danger that will re-
sult in electrocution 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.
This symbol denotes information intended to assist the user in making op-
timum use of the product.
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
1.2.2 Repair service
Repair, calibration, update and replacement service for Bender products
• 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 guarantee for Bender devices, which includes an in-house repair service or
replacement devices at no extra cost
Please send the devices for repair to the following address:
Bender GmbH, Repair-Service,
Londorfer Str. 65,
35305 Grünberg
Telephone: [phone]*
Fax: [phone]
In Germany only: 0700BenderHelp (Telephone and Fax)
E-Mail: [e-mail]
Telephone: [phone]** (technical)
[phone]**, -785** (sales)
Fax: [phone]
E-Mail: [email protected]

Important informationImportant information
isoUG425_D00220_02_M_XXEN/05.2018
6
1.2.3 Field service
On-site service for all Bender products
• Commissioning, configuring, maintenance, troubleshooting of Bender products
• Analysis of the electrical installation in the building (power quality test, EMC test,
thermography)
• Training courses for customers
*365 Tage von 07:00 - 20:00 Uhr (MEZ/UTC +1)
**Mo-Do 07:00 - 16:00 Uhr, Fr 07:00 - 13:00 Uhr
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 -> Know-how -> Seminars.
1.4 Delivery conditions
Bender sale and delivery conditions apply.
For software products the "Softwareklausel zur Überlassung von Standard-Software als
Teil von Lieferungen, Ergänzung und Änderung der Allgemeinen Lieferbedingungen für
Erzeugnisse und Leistungen der Elektroindustrie" (software clause in respect of the licen-
sing of standard software as part of deliveries, modifications and changes to general deli-
very conditions for products and services in the electrical industry) set out by the ZVEI
(Zentralverband Elektrotechnik- und Elektronikindustrie e. V.) (German Electrical and
Electronic Manufacturer's Association) also applies.
Sale and delivery conditions can be obtained from Bender in printed or electronic 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 sto-
rage temperatures can be ensured.
Telephone: [phone]**, -762** (technical)
[phone]** (sales)
Fax: [phone]
E-Mail: [e-mail]
Internet: www.bender.de
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 following 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 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 recommended by the
manufacturer.
This operating manual, especially the safety instructions, must be observed by all person-
nel 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 device. Ask
your supplier if you are not sure how to dispose of the old equipment.
The directive on waste electrical and electronic equipment (WEEE directive) and the di-
rective on the restriction of certain hazardous substances in electrical and electronic
equipment (RoHS directive) apply in the European Community. In Germany, these po-
licies 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 13 August 2005 must be taken back by the
manufacturer and disposed of properly.
For more information on the disposal of Bender devices, refer to our homepage at
www.bender.de/Service & support.

isoUG425_D00220_02_M_XXEN/05.2018
7
Safety instructions
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 Germany, the applicable local standards and regulations
must be complied with. The European standard EN 50110 can be used as a guide.
Only qualified personnel are permitted to carry out the work necessary
to install, commission and run a device or system.
DANGER
Risk of fatal injury from 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 installati-
on has been de-energised. Observe the rules for working on electrical ins-
tallations.
2.3 Intended use
The ISOMETER® monitors the asymmetrical insulation resistance RFof unearthed DC sys-
tems (IT systems) with nominal system voltages of DC 12 … 120 V. Put another way, it is
an insulation monitoring device for earth fault detection in unearthed DC systems (IT sys-
tems) up to 120 V DC. The maximum permissible system leakage capacitance Ceis 50 F.
The isoUG425 is not an insulation monitoring device as described in IEC
61557-8/EN 61557-8. The offset voltage measured in the event of an insu-
lation fault on a system conductor is metrologically evaluated. Using a
passive measurement method, the isoUG425 records insulation faults
that cause an asymmetry to PE in the IT system. Symmetrical insulation
faults (i.e. equally large insulation faults on the positive and negative
power conductors to earth) are not detected or recorded.
In the event of an alarm message of the ISOMETER®, the insulation fault
should be eliminated as quickly as possible.
If the ISOMETER® is installed inside a control cabinet, the insulation fault
message must be audible and/or visible to attract attention.

isoUG425_D00220_02_M_XXEN/05.2018
8
Function
3. Function
3.1 Device features
• Monitoring of the asymmetrical insulation resistance RFin unearthed DC systems
• Measurement of the nominal system voltage Un(True RMS and DC) with undervolt-
age and overvoltage detection
• Measurement of residual voltages system to earth (L+/PE and L-/PE)
• Configurable adaptation to the system leakage capacitance Ceup to 50 F
• Selectable start-up delay, response delay and delay on release
• Two separately adjustable response value ranges of 1...100 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 of the relays selectable
• Measured value indication via a multi-functional LC display
• Fault memory can be activated
• RS-485 interface (galvanically isolated) with 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
3.2 Function description
The ISOMETER® measures, from a minimum nominal system voltage, the asymmetrical in-
sulation resistance RFbetween the system to be monitored (L+, L-) and earth (PE). The
RMS value and the DC value of the nominal system voltage Unbetween L+ and L- as well
as the residual voltages UL+e (between L+ and earth) and UL-e (between L- and earth) are
also measured.
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 signalling assign-
ment set in the "out" menu. In addition, the operation of the relay (n.c./n.o.) can be set
and the fault memory "M", activated.
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 posi-
tion and the alarm LEDs "AL1"/"AL2" go out. If the fault memory is activated, the alarm re-
lays 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 (COM460IP) or the Modbus RTU.
3.2.1 Monitoring the insulation resistance
The two parameters that monitor the insulation resistance, "R1" and "R2", can be found in
the response value menu "AL" (see table on Page 16). The value R1 can only be set higher
than the value R2. If the insulation resistance RFreaches or falls below the activated val-
ues R1 or R2, then this leads to an alarm message. If RFexceeds the values R1 or R2 plus
the hysteresis value (see table on Page 16), the alarm will be cleared.
3.2.2 Undervoltage/overvoltage monitoring
In the response value menu "AL" (Page 16), the parameters ("U <" and "U >") for monitor-
ing the nominal system voltage Uncan be activated or deactivated. The maximum und-
ervoltage value is limited by the overvoltage value.
The DC value of the system voltage is monitored. If the nominal system voltage Unreach-
es, 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 will be triggered even if the overvoltage limit value has been deactivated. The
alarm will be deleted when the limit values plus the hysteresis (see Page 16) are no longer
violated.
3.2.3 Self test/error codes
The integrated self test function tests the function of the insulation monitoring device,
the connection to earth and the polarity of the nominal system voltage Un. The alarm re-
lays are not switched during the self test. This can be changed using the parameter "test"
in the signalling assignment (menu "out", Page 17). 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 when factory
setting has been selected, relay "K2" switches.
The relays can be assigned to a device error with the parameter "Err" in the "out" menu in
the alarm assignment.

FunctionFunction
isoUG425_D00220_02_M_XXEN/05.2018
9
Error codes
If, contrary to expectations, a device error should occur, error codes will appear on the
display. Some of these are described below:
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 fac-
tory 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.
Automatic self test
The device runs a self test after connecting the supply voltage Usand later every 24 h (se-
lectable: off, 1h, 24 h - See Page 18).
Manual self test
By pressing the external test/reset button or the test button "T" on the device
> 1.5 s, a self test is started.
While holding down the test button "T", all device-relevant display elements appear on
the display.
Error code Meaning
E.01
PE connection fault
The connections "E"or "KE"to earth are interrupted.
Action:
Check connection, eliminate fault. The error code will be erased auto-
matically once the fault has been eliminated.
E.02
Wrong polarity
The monitored DC system has the wrong polarity.
Action:
Check connection, eliminate fault. The error code will be erased auto-
matically once the fault has been eliminated.
E.05 Measurement technique error/calibration invalid
for the current software version
E.08
Calibration error during the device test
Action:
If the error continues to exist after checking the device connections,
there is an error inside the device.
3.2.4 Malfunction
In addition to the described self test, several functions in the insulation monitoring de-
vice 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.
3.2.5 Signalling assignment of the alarm relays K1/K2
The messages "device error", "insulation fault", "insulation impedance fault", "undervolt-
age/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 L+ and the messages "-R1" and "-R2" indicate an insulation fault assigned to
conductor L-.
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 and setting the parameter value to "S.AL = on", the ISOMETER® starts with
the insulation measured value RF= 0  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 recom-
mended that the value set for the "S.AL" parameter value is identical for both relays.
3.2.6 Measuring and response times
The measuring time is the period essential for the detection of the measured value. The
measuring time is reflected in the operating time tae.
Total response time tan
The total response time tan is the sum of the operating time tae and the response delay
time ton.
Operating time tae
The operating time tae is the time required by the ISOMETER® to determine the measured
value. The insulation resistance measured value depends on the insulation resistance RF
and the system leakage capacitance Ce. For example, a set maximum permissible system
leakage capacitance of Ce= 1 µF and an insulation fault of RF= 12 k (Ran = 25 k) in a
120 V DC system results in an operating time of tae < 1 s. High system leakage capacitanc-
es and system interferences lead to longer operating times. Increasing the maximum per-
missible system leakage capacitance Ce(parameter C in the "Set" menu) over 1 µF may
extend the guaranteed operating time of 1 s proportionally to the increase of the
capacitance.

FunctionFunction
isoUG425_D00220_02_M_XXEN/05.2018
10
Response delay ton
The response delay ton can be set uniformly for all messages in the "t" menu using the pa-
rameter "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 measured value
is violated for the period of ton without interruption. Every time the threshold value is vi-
olated within the time ton, the response delay "ton" restarts once again.
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 hast 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 with-
out 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.
3.2.7 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).
3.2.8 Maximum permissible leakage capacitance
A set capacitance value above 1 µF extends the guaranteed operating time tae propor-
tionally. It should only be increased if a corresponding system leakage capacitance Ceis
present in the system to be monitored and therefore, an extended measuring time is re-
quired. A system leakage capacitance Ce higher than the set value may lead to false
alarms.
3.2.9 Factory setting FAC
Activating the factory setting will reset all modified settings, with the exception of the
interface parameters, to the default upon delivery.
3.2.10 External, combined test or reset button T/R
Reset= Press the external button < 1.5 s
Test= Press the external button > 1.5 s
Stop measuring function = Press and hold the external button
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 par-
allel connection of several test or reset inputs for testing multiple insulation monitoring
devices is not allowed.
3.2.11 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 LED and relay alarm messages re-
main available until they are deleted by using the reset button (internal/external) or the
supply voltage Usis turned off.
3.2.12 History memory HiS
When the first error occurs after clearing the history memory, all measured values (that
are marked in the table on Page 18) are stored 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".

FunctionFunction
isoUG425_D00220_02_M_XXEN/05.2018
11
3.2.13 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 inter-
face (BMS bus protocol). Data 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 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 approximate-
ly 1 second. 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 27.
The parameter address, baud rate and parity for the interface protocols are configured in
the "out" menu.
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 indi-
cates the activated BMS protocol. In this case, the baud rate for the BMS
protocol is set to 9,600 baud. If the baud rate is set unequal to "---", the
Modbus protocol with configurable baud rate is activated.

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Installation, connection and commissioning
4. Installation, connection and commissioning
4.1 Mounting
• DIN rail mounting:
Snap the mounting clip at the rear of the device onto the DIN rail so that it sits
securely or
• Screw mounting:
Use a tool to position the rear mounting clips so that they project beyond the enclo-
sure (a second mounting clip is required, see ordering information). Fix the device
with two M4 screws, see the following sketch.
The dimension diagram and sketches outlining how the device can be screw-mounted
DANGER
Risk of electric shock!
Touching uninsulated live conductors can result in death or serious injury.
Therefore avoid any physical contact with active conductors and ensure
compliance with the regulations for working on electrical installations.
If the ISOMETER® is used in rail vehicles, it must be ensured that the ISOME-
TER® is installed within a control cabinet that complies with the fire pro-
tection requirements of the DIN EN 45545-2.
and the push-wire terminal connection are shown below:
All dimensions in mm
The front plate cover can be opened at the lower part marked with an arrow.
4.2 Wiring diagram
The supply voltage Uson A1/A2 can be connected to the system voltage (L+/L-) if the sys-
tem voltage is ≥ DC 24 V. Otherwise, a separate supply is required. The terminals "A1" and
"A2" have to be connected to the supply voltage Usaccording to IEC 60364-4-43, which
means, the connections have to be protected against short circuit by means of a protec-
tive device (a 6 A fuse is recommended).
Devices for protection against short circuit in conformity with IEC 60364-4-43 for the cou-
pling of terminals "L+" and "L-" to the IT system to be monitored can be omitted if the wir-
ing is carried out in such a manner as to reduce the risk of a short circuit to a minimum.
Only one ISOMETER® may be controlled via a test/reset button. It is not allowed to use a
parallel connection of several test or reset inputs for combined testing of ISOMETER®s.
93
45
67,5
36
31,1
47,5
74,5
2
2
2
1
3
Click
107 mm

Installation, connection and commissioningInstallation, connection and commissioning
isoUG425_D00220_02_M_XXEN/05.2018
13
Connect the device as illustrated in the wiring diagram:
L+
KE
14 24 11
K1 K2
E
T/R
Test/Reset
L
COM460IP
RS-485
L+
L-
PE
AB
R
ON
TR
MENU
AL1 AL2 k
<k
ISOMETER
isoUG425
L+ L-
EKEA1A2
14 24 11
T/R AB
R
on
off
US
A1 A2
The supply voltage U s applied
to A1/A2 can be provided by the
system voltage (L +/L-) when the
system voltage is ≥ 24V DC. Otherwise
a separate power supply is needed.

Installation, connection and commissioningInstallation, connection and commissioning
isoUG425_D00220_02_M_XXEN/05.2018
14
For details about the conductor cross sections required for wiring, refer to the technical
data from Page 28. Wiring diagram legend:
Terminal Connectors
A1, A2 Connection to the supply voltage Usvia fuse (line protection).
If being 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
L+, L– Connection to the DC 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 resistor
Example: Connection of a BMS Ethernet gateway COM460IP
* For UL applications:
Use 60/75°C copper lines only!
For UL and CSA applications, the supply voltage Usmust be protected via
5A fuses.
4.3 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 4 minutes. The standard display then appears showing the present
insulation resistance, e.g.:
The pulse symbol signals an error-free update of the resistance measured value. 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". Whilst the test button is
pressed and held down (> 1.5 s), 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 8). 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 the factory settings for suitability.
Are the settings suitable for the installation to be monitored?
The list of factory settings is shown in the tables from Page 16.
5. Check the function using a genuine insulation fault.
Check the ISOMETER® in the system being monitored against earth, e.g. via a suita-
ble resistance.

isoUG425_D00220_02_M_XXEN/05.2018
15
Operation of the device
5. 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:
- Navigate up or down in the menu settings
- Increase or decrease 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:
Exits 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
The areas of the display that can be configured flash!
5.1 Display elements in use
Device front/display Function
ON
AL1
AL2
green - on
yellow - alarm
yellow - alarm
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)
1
U: Nominal system voltage Un
R: Insulation resistance RF
C: System leakage capacitance Ce
2Monitored conductor
3
= : Voltage type DC
=~ : Voltage type RMS
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
ON AL1 AL2
T MENU R
+
test onoff MAdr
L1L2 C
<
>
s
kM %
Fµ
{
{
{
{
12 3
4
567
8
{
9
Hz
{
10
: Error-free measured value update
Assignment according to
the table on Page 17

Operation of the deviceOperation of the device
isoUG425_D00220_02_M_XXEN/05.2018
16
5.2 Menu structure
Menu item Parameter
AL Querying and setting response values
out Configuring fault memory, alarm relays and interface
tSetting delay times and self test cycles
SEt Setting device control parameters
InF Querying software version
HiS Querying and clearing the history memory
ESC Go to the next higher menu level
Enter
or
t > 5 Min.
k
R
Standard display
R [ kΩ ]
U L1 L2 [ V
RMS
]
U L1 L2 [ V
DC
]
UL1 [ V
DC
]
UL2 [ V
DC
]
Measurement display
Menu
Esc
Menu selection
AL
out
t
SEt
InF
HiS
ESC
Enter
Esc
Parameter selection
P1
. . .
Pn
ESC
Optional Password
Edit parameters
Save parameters
Enter
Enter
Enter
Esc
Function Button Conrm
Enter
Menu
Esc
Test
Reset
Select, acknowledge input
Call menu
Exit menu item
Start device test
Clear fault menu
/ MENU Kurz
> 1.5 s
> 1.5 s
> 1.5 s
> 1.5 s
/ MENU
/ MENU
/ T
/ R
5.3 "AL" menu
5.3.1 Response value setting
The two parameters that monitor the insulation resistance, "R1" and "R2", can be found in
the response value menu "AL". 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, this leads
to an alarm message. If RFexceeds the values R1 or R2 plus the hysteresis value (see table
below), the alarm will be cleared.
Also in the response value menu "AL" both parameters ("U <" and "U >") for monitoring
the nominal system voltage Uncan be activated or deactivated. The maximum undervolt-
age value is limited by the overvoltage value.
FAC = Factory setting; Cs = Customer settings
Display Activation Setting value Description
FAC Cs Value range FAC Cs
R1 < R2 … 100 50 k Pre-alarm value Ran1
Hys. = 25 %/min. 1 k
R2 < 1 … R1 25 k Alarm value Ran2
Hys. = 25 %/min. 1 k
U < off 8 … U> 8 V
Alarm value
undervoltage DC
Hys . = 5 %/min. 1 V
U > off U< … 144 140 V
Alarm value
overvoltage DC
Hys. = 5 %/min. 1 V

Operation of the deviceOperation of the device
isoUG425_D00220_02_M_XXEN/05.2018
17
5.4 "out" menu
5.4.1 Configuration of the relay operating mode
FAC = Factory setting; Cs = Customer settings
5.4.2 Relay alarm assignment "r1" and "r2" and LED assignment
In the alarm assignment, each alarm is assigned to the corresponding relay with the set-
ting "on". The LED indication is directly assigned to the alarms and is not related to the
relays.
In the event of an unsymmetrical insulation fault, only the alarm corresponding to the as-
signed conductor (L+ or L-) will be displayed. .
Relay K1 Relay K2 Description
Display FAC Cs Display FAC Cs
n.c. n.c. Operating mode of the relay n.c/n.o.
K1 "r1" K2 "r2" LEDs Alarm
description
Display FAC Cs Display FAC Cs ON AL1 AL2
off on    Device error E.xx
r1
+R1 <  on r2 +R1 <  off   
Pre-alarm R1
Fault RF at L+
r1
-R1 <  on r2 -R1 <  off   
Pre-alarm R1
Fault RF at L-
r1
+R2 <  off r2
+R2 <  on Alarm R2
Fault RF at L+
r1
-R2 <  off r2
-R2 <  on Alarm R2
Fault RF at L-
r1
U < V off r2
U < V on Alarm UnDC
undervoltage
r1
U > V off r2
U > V on   
Alarm UnDC
Overvoltage
1
2
1
Err
2
Err
FAC = Factory setting; Cs = Customer settings
: LED off : LED flashes : LED on
5.4.3 Fault memory configuration
FAC = Factory setting; Cs = Customer settings
5.4.4 Interface configuration
FAC = Factory setting; Cs = Customer settings;
( ) = User setting that is not modified by FAC.
r1
test off r2 test off   
Manually
started
device test
r1
S.AL off r2 S.AL off    Device start with alarm
Display FAC Cs Description
Moff Memory function for alarm messages (fault memory)
Display Setting value Description
Value range FAC Cs
Adr 0/3 … 90 3 ( ) BusAdr.
Adr = 0 deactivates BMS as well as
Modbus and activates isoData with
continuous data output
(115k2, 8E1)
Adr 1 --- /
1.2k … 115k “---“ ( ) Baud rate
“---“ : BMS bus (9k6, 7E1)
“1.2k“ … “115k“ -->
Modbus (variable, var.)
Adr 2
8E1
8o1
8n1
8E1 ( )
Modbus
8E1 - 8 data bits
even parity, 1 stop bit
8o1 - 8 data bits
odd parity, 1 stop bit
8n1 - 8 data bits
no parity, 1 stop bit
K1 "r1" K2 "r2" LEDs Alarm
description
Display FAC Cs Display FAC Cs ON AL1 AL2

Operation of the deviceOperation of the device
isoUG425_D00220_02_M_XXEN/05.2018
18
5.5 "t" menu
5.5.1 Time configuration
FAC = Factory setting; Cs = Customer settings
5.6 "SEt" menu
5.6.1 Function configuration
FAC = Factory setting; Cs = Customer settings
Display Setting value Description
Value
range FAC Cs
t0 … 10 0 sStart-up time when starting the device
ton 0 … 99 0 sResponse delay K1 and K2
toff 0 … 99 0 sDelay on release K1 and K2
test OFF/1/24 24 h Repetition time device test
Display Activation Setting value Description
FAC Cs Value
range FAC Cs
off 0 . . . 999 0Password for parameter setting
C1 . . . 50 1µF
Maximum permissible leakage
capacitance Ce
S.Ct on Device test during device start
FAC Restore factory settings
SYS For Bender Service only
5.7 Measured value display and history memory
RFis continuously indicated on the display (standard display). All other measured value
displays switch to the standard display after a maximum of 5 min. The pulse symbol indi-
cates a current measured value. If this symbol does not appear, the measurement is still
running and the latest valid measured value will be displayed. The symbols "<" or ">" will
be displayed additionally to the measured value when a response value has been
reached or violated, or the measured value is below or above the measuring range.
: The measured value is indicated in the history memory.
HiS Display Description
R k Insulation resistance RF
1 k ... 1 M Resolution 1 k
U L1 L2 =~ V
Nominal system voltage L+ - L- UnRMS
0 VRMS … 99.9 VRMS Resolution 0.1 VRMS
100 VRMS … 150 VRMS Resolution 1 VRMS
U L1 L2 =V
Nominal system voltage L+ - L- UnDC
0 VDC … 99.9 VDC Resolution 0.1 VDC
100 VDC … 150 VDC Resolution 1 VDC
±U L1 = V
Residual voltage L+ - PE UL+e
0 VDC … 99.9VDC Resolution 0.1 VDC
100 VDC … 150 VDC Resolution 1 VDC
±U L2 = V
Residual voltage L- - PE UL-e
0 VDC … 99.9VDC Resolution 0.1 VDC
100 VDC … 150 VDC Resolution 1 VDC

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19
Data access using the BMS protocol
6. Data access using the BMS protocol
The BMS protocol is an essential component of the Bender measuring device interface
(BMS bus protocol). ASCII characters are used for data transfer.
BMS channel no. Operation value Alarm
1RFPre-alarm R1
2RFAlarm R2
3UnRMS Overvoltage
4UnDC Undervoltage
5UnDC Overvoltage
6--- Connection fault earth (E.01)
7--- Connection fault system (E.02)
8--- All other device faults (E.xx)
9Fault location [%] ---
10 UL+e ---
11 UL-e ---
12 Update counter ---
13 --- ---
14 --- ---
15 --- ---

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Data access using the Modbus RTU protocol
7. Data access using the Modbus RTU protocol
Requests to the ISOMETER® can be made using the function code 0x03 (read multiple reg-
isters) or the command 0x10 (write multiple registers). The ISOMETER® generates a func-
tion-related answer and sends it back.
7.1 Reading out the Modbus register from the ISOMETER®
The required Words of the process image can be read out from the "Holding registers" of
the ISOMETER® using the function code 0x03. For this purpose, the start address and the
number of the registers to be read out have to be entered. Up to 125 Words (0x7D) can
be read with one single request.
7.1.1 Command of the master to the ISOMETER®
In the following example, the master of the ISOMETER® requests the content of the regis-
ter 1003 with the address 3. The register contains the channel description of measuring
channel 1.
7.1.2 The ISOMETER® answers the master
Byte Name Example
Byte 0 ISOMETER® Modbus address 0x03
Byte 1 Function code 0x03
Byte 2, 3 Start address 0x03EB
Byte 4, 5 Number of registers 0x0001
Byte 6, 7 CRC16 Checksum 0xF598
Byte Name Example
Byte 0 ISOMETER® Modbus address 0x03
Byte 1 Function code 0x03
Byte 2 Number of data bytes 0x02
Byte 3, 4 Data 0x0047
Byte 7, 8 CRC16 Checksum 0x81B6
7.2 Writing the Modbus register (parameter setting)
Registers in the device can be modified with the Modbus command 0x10 (set multiple
registers). Parameter registers are available from address 3000. The content of the regis-
ter is listed in the table on Page 22
7.2.1 Command of the master to the ISOMETER®
In this example, the master addresses the ISOMETER® with address 3 and requests that
the content of the register with address 3003 is set to 2.
7.2.2 The ISOMETER® answers the master
Byte Name Example
Byte 0 ISOMETER® Modbus address 0x03
Byte 1 Function code 0x10
Byte 2, 3 Start register 0x0BBB
Byte 4, 5 Number of registers 0x0001
Byte 6 Number of data bytes 0x02
Byte 7, 8 Data 0x0002
Byte 9, 10 CRC16 Checksum 0x9F7A
Byte Name Example
Byte 0 ISOMETER® Modbus address 0x03
Byte 1 Function code 0x10
Byte 2, 3 Start register 0x0BBB
Byte 4, 5 Number of registers 0x0001
Byte 6, 7 CRC16 Checksum 0x722A