ABB REX 521 Use and care manual

Industrial IT enabled products from ABB are the building blocks for greater
productivity, featuring all the tools necessary for lifecycle product support in
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Issued: 27.6.2001
Version: D/24.11.2003
We reserve the right to change data without prior notice.
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Technical Reference Manual, General
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2.1. General .........................................................................................7
2.2. Application .....................................................................................8
2.3. Hardware versions ........................................................................8
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4.1. Functional description .................................................................10
4.1.1. Parametrization ................................................................10
4.1.1.1. Local parametrization .........................................10
4.1.1.2. External parametrization ....................................10
4.1.1.3. Relay Setting Tool view ......................................11
4.1.1.4. Graphical I/O Setting Tool ..................................12
4.1.1.5. Factory settings ..................................................12
4.1.2. Non-volatile memory ........................................................13
4.1.3. Real-time clock ................................................................13
4.1.4. Auxiliary voltage ...............................................................14
4.1.4.1. Power supply versions .......................................14
4.1.4.2. Low auxiliary voltage indication ..........................14
4.1.5. Overtemperature indication ..............................................15
4.1.6. Analogue channels ..........................................................15
4.1.6.1. Scaling the rated values of the protected unit for
analogue channels 15
4.1.6.2. Technical data of the measuring devices ...........16
4.1.7. Digital inputs ....................................................................18
4.1.7.1. Filtering of digital inputs .....................................18
4.1.7.2. Inversion of digital inputs ....................................19
4.1.8. Outputs ............................................................................19
4.1.8.1. High-speed power output (HSPO) .....................19
4.1.8.2. Single-pole power outputs (PO) .........................20
4.1.8.3. Signalling outputs (SO) ......................................20
4.1.9. Testing inputs and outputs ...............................................21
4.1.10.Trip-circuit supervision .....................................................21
4.1.11.Self-supervision ...............................................................23
4.1.11.1.Fault indication ...................................................24
4.1.11.2.Fault indication texts ..........................................25
4.1.12.Serial communication .......................................................26
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Technical Reference Manual, General
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4.1.12.1.Optical communication port on the rear panel ...26
4.1.12.2.Isolated RS-485 connection on the rear panel ..27
4.1.12.3.Front panel optical connection for a PC .............27
4.1.12.4.The service pin located on the rear panel ..........27
4.1.12.5.SPA bus .............................................................27
4.1.12.6.LON bus ............................................................29
4.1.12.7.IEC 60870-5-103 bus ........................................31
4.1.12.8.Modbus bus .......................................................31
4.1.13.Time synchronization .......................................................32
4.1.14.Display panel (HMI) .........................................................33
4.1.15.Indication LEDs ...............................................................34
4.1.16. Alarm LEDs ....................................................................34
4.1.16.1.Special features of alarm LEDs .........................34
4.1.16.2.Writing signal names on alarm LED label ..........35
4.2. Design description ......................................................................37
4.2.1. Technical data ........................................................37
4.2.2. Terminal diagram of REX 521: Basic ...............................41
4.2.3. Terminal diagram of REX 521: Medium ...........................42
4.2.4. Terminal diagram of REX 521: High ................................43
4.2.5. Terminal diagram of REX 521: Sensor ............................44
4.2.6. Terminal connections ......................................................45
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7.1. Revision identification .................................................................49
7.2. Changes and additions to earlier released revision B ................49
7.3. Configuration, setting, and SA system tools ...............................50
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10.1.Functions supported by REX 521 ..............................................55
10.2.General principle of application data mapping ...........................55
10.3.Principle of the protection functions mapping ............................56
10.4.Class 2 data ...............................................................................56
10.5.Default mappings .......................................................................57
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Technical Reference Manual, General
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Version D/24.11.2003
-Changes and/or new entries in tables “Hardware versions of REX 521“, “Power outputs“, “Data
communication”, “Display language codes”, and “Class 1 data signals”.
-Changes in chapters “Introduction”, “External parametrization”, “Scaling of the rated values of the
protected unit for analogue channels”, “Technical data of the measuring devices”, “Trip-circuit
supervision”, “Serial communication”, “Ordering information”, “Revision identification”, “Changes
and additions to earlier released revision”, “Configuration, setting, and SA system tools”, References”,
“Class 2 data”, “Appendix B: Parameters visible only in the relay”, and “Appendix C: Parameters
which cause reset“.
-New chapters: “Graphical I/O Setting Tool“, “Factory settings“, “Modbus bus“, “Isolated RS-485
connection on the rear panel“, and “Alarm LEDs”.
-Changes in figures “REX 521 protection relay”, ”Block_Basic”, “Block_Medium”, “Block_High”,
“Highsensor”, “RearViewBasic”, “RearViewMedium”, “RearViewHigh”, “RearViewSensor”, and
“OrderNo”.
-New figures: “Modbus_syst”.
-TCS changed to TCS1.
-3I MCS changed to MCS 3I.
-3U MCS changed to MCS 3U.

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Technical Reference Manual, General
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Dangerous voltages can occur on the connectors, even though the
auxiliary voltage is disconnected
National and local electrical safety regulations must always be
followed
The device contains components that are sensitive to electrostatic
discharge
The frame of the device has to be carefully earthed
Only a competent electrician is allowed to carry out the electrical
installation
Non-observance can result in death, personal injury or substantial
property damage
Breaking the sealing tape on the rear panel of the device will result in
loss of warranty and a proper operation will no longer be guaranteed
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1MRS 751108-MUM 3URWHFWLRQ5HOD\
Technical Reference Manual, General
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This document provides a general description of the protection relay REX 521
Revision C. For more information about the earlier revisions, refer to section
“Revision history of REX 521”on page 49.
For detailed information about the separate functions, refer to 5(;7HFKQLFDO
5HIHUHQFH0DQXDO6WDQGDUG&RQILJXUDWLRQV (see “References”on page 51).
 *HQHUDO
The protection relay REX 521 is designed for protection, control, measuring and
supervisioninmediumvoltagenetworks.Typicalapplicationsincludeincomingand
outgoing feeders as well as substation protection. The protection relay is provided
with energizing inputs for conventional current and voltage transformers. Also a
hardware version with inputs for current and voltage sensors is available.
The protection relay is based on a multiprocessor environment. The HMI1(human-
machine interface) including an LCD (liquid chrystal display) with different views
makes the local use easy and informs the user via indication messages. Modern
technology is applied both in hardware and software solutions.
The REX 521 is part of the substation automation concept for Distribution
Automation and extends the functionality and flexibility of the concept further.
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1. HMI is referred to as MMI (man-machine interface) in the relay and in the Relay
Setting Tool.

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1MRS 751108-MUM
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Technical Reference Manual, General
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The REX 521 is designed for protection of incoming and outgoing feeders in
medium voltage distribution substations. Further, the relay can, for example, be
applied to back-up protection of power transformers and back-up for high voltage
line protection relays.
Several standard configurations are available for the protection relay. For more
information, refer to 5(;7HFKQLFDO5HIHUHQFH0DQXDO6WDQGDUG
&RQILJXUDWLRQV (see “References”on page 51).
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7UDQVIRUPHUPRGXOHV0 0 1111
Transformers
•Currenttransformers1/5A 4441
• Current transformers 0.2/1 A 1 1 1
• Voltage transformers 100 V 1 4 1
6HQVRUFKDQQHOV
• Current sensor inputs 3
• Voltage sensor inputs 3
0DLQ&38PRGXOHV 1111
CPU_SP (SPA/ IEC/MODBUS plastic)
CPU_SG (SPA/ IEC/MODBUS glass)
CPU_LP (SPA/ IEC/ LON/MODBUS plastic)
CPU_LG (SPA/ IEC/ LON/MODBUS glass)
3RZHUVXSSO\PRGXOHV 1111
PS_87H (DItresh.=80 Vdc)
PS_87L (DItresh.=18 Vdc)
'LVSOD\PRGXOH 1111
2 x 16 character display
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1MRS 751108-MUM 3URWHFWLRQ5HOD\
Technical Reference Manual, General
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If the environmental conditions differ from those specified in section “Technical
data”on page 37, as to temperature and humidity, or if the environmental conditions
aroundthe protection relay containschemically active gases ordust, therelay should
be visually inspectedin association withthe secondarytesting. The visualinspection
should focus on:
•Signs of mechanical damage to the relay case and terminals.
•Signs of corrosion on terminals or on the case.
•For information about the maintenance of relays, refer to section “Service”on
page 47.
Protection relays are measuring instruments and should be handled with
care and protected against moisture and mechanical stress, especially
during transport.
!

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1MRS 751108-MUM
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Technical Reference Manual, General
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To ensure that a protection function block protects the feeder in the desired manner,
the default values of parameters must be checked and set before taking the function
block into use.
The parameters can be set either locally over the HMI or externally via the serial
communication using Relay Setting Tool. See “Serial communication”on page 26.
 /RFDOSDUDPHWUL]DWLRQ
The parameter to be changed is entered by navigating in the menu structure. For
detailed instructions, refer to 2SHUDWRU¶V0DQXDO (see “References”on page 51).
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The Relay Setting Tool and/or Graphical I/O Setting Tool is used for external
parametrization of the protection relay. The parameters can be set by using a PC and
downloaded to the protection relay over a communication port. The menu structure
of the setting tool, including views relating to parametrization and settings, is the
same as the menu structure of the protection relay1. The use of the tool is instructed
in 7RROVIRU5HOD\VDQG7HU LQDOV8VHU¶V*XLGH (see “References”on page 51).
1. A few parameters are visible only in the relay, see the list on page 63.

1MRS 751108-MUM 3URWHFWLRQ5HOD\
Technical Reference Manual, General
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To improve usability, a REX 521 specific pull-down menu, 9LHZ, with three views
has been created to the Relay Setting Tool.
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The 6HWWLQJV view includes the parameters for setting of all the function blocks. The
&RQILJXUDWLRQ view includes signalling and hardware related settings. The
parameters in the &RQILJXUDWLRQ view are advised to be set during commissioning
and service because some of the parameters cause resetting of the device. Refer to

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1MRS 751108-MUM
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Technical Reference Manual, General
5(;
“Appendix C: Parameters which cause reset”on page 64 for a list of these
parameters. Measured values and registered data, for example current, digital input
states, can be uploaded by means of the 0HDVXUHPHQWV5HJLVWHUHG'DWD view.
When uploading or downloading parameters with Relay Setting Tool by
using the option $OO, it covers only the parameters of the selected view
(that is, 6HWWLQJV, &RQILJXUDWLRQ, or 0HDVXUHPHQWV5HJLVWHUHG
'DWD).
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To make the external relay parametrization even easier, a REX 521 specific
Graphical I/O Setting Toolhas been addedto the RelaySetting Tool.The Graphical
I/O Setting Tool offers a user-friendly environment for better visualization and
makes it easier to get a complete overview of the settings.
The tool is used for setting input switchgroups, output switchgroups, and Alarm
LED switchgroups. Using this tool is instructed in 7RROVIRU5HOD\VDQG7HU LQDOV
8VHUV*XLGH (see “References”on page 51).
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The factory settings for the relay can be restored by selecting “Activate”from HMI
path Configuration\General\Software\Factory settings. After
this, the relay will reset itself immediately and start with the factory-set parameter
values.
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1MRS 751108-MUM 3URWHFWLRQ5HOD\
Technical Reference Manual, General
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When starting again, the relay display shows the text
WARNING EEPROM -> FLASH
on the display. This means that the calibration parameters have been read from the
MIM card and copied to the non-volatile memory of the CPU card. After ten
seconds, the relay will reset itself again, and takes the correct calibration parameters
into use.
 1RQYRODWLOHPHPRU\
The protection relay is equipped with a non-volatile memory for preserving
important data during auxiliary supply breaks. For example, when a setting value is
changed, the new value is stored in the memory at the moment of sending it to the
relay, without additional store commands. The memory does not need batteries, and
a lifelong service is guaranteed.
Following data is stored in the non-volatile memory:
•Setting values
•Display state
•Lockout state
•Recorded values1
•Last 50 events
When the relay is restarted, the same LED indication and text as beforethe auxiliary
supply break are restored on the display. More information about the alarm LEDs
can be found in chapter “Alarm LEDs”on page 34.
Recorded values are stored from start, trip and other important events. After an
auxiliary power break, time and date and fault currents for the three last events can
be viewed by navigating to the “Recorded values”section of the function block that
caused an indication.
The last 50 events that occurred before the auxiliary power supply break can be
viewed in the HMI event buffer. Time and date for the events are also restored.
 5HDOWLPHFORFN
The real-time clock (RTC) is used for time stamping of events. It is also running
during auxiliary power breaks. When the supply is re-established, the relay sets the
right time and new events are stamped accordingly.
The protection relay is provided with a 1-week capacitor back-up protection2that
enables the internal clock to keep time in case of an auxiliary power failure.
The unnecessary restoring of factory settings should be avoided because
all the parameter settings that are written earlier to the relay will be lost,
that is, overwritten with the default values. During normal use this can
cause a protection function to trip when the settings are suddenly changed.
!
1. Because the storing of the recorded values is a background task, it might be affected
by a sudden auxiliary power failure.
2. Capacitor ageing may decrease the back-up time.

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 $X[LOLDU\YROWDJH
For its operation, the protection relay requires a secured auxiliary voltage supply.
The protection relay’s internal power supply module forms the voltages required by
the protection relay electronics. The power supply module is a galvanically isolated
(flyback-type) DC/DC converter. A green LED indicator on the front panel is lit
when the power supply module is in operation.
 3RZHUVXSSO\YHUVLRQV
There are two basic versions of power supply modules available for REX 521
protection relays: type PS_87H and type PS_87L.
The input voltage range of the power supply module is marked on the front panel of
the REX 521 unit. The power supply version is specified by a letter in the order
numberof the protection relay(refer to section “Ordering information”on page 48).
The voltage range of the digital inputs is tied tothe selectedpower supply. Ifa power
supply version with the higher rated input voltage is selected, the protection relays
will be delivered with digital inputs thatalso havethe higher rated input voltage. The
digital input, DI9, on the CPU module has also lower rated input voltage.
The auxiliary voltages of power supply modules and the corresponding rated input
voltages of digital inputs are:
For further technical data of the power supply, refer to Table 4.2.1-2 on page 37.
 /RZDX[LOLDU\YROWDJHLQGLFDWLRQ
The relay is provided with a low auxiliary voltage indication feature. The power
supply module issues an internal alarm signal when a drop in the power supply
voltage is detected. The alarm signal is activated if the power supply voltage falls
about 10% below the lowest rated dc input voltage of the power supply module, see
the table below:
The indication of a low auxiliary voltage (ACFail) can be seen as an event via serial
communication.
3RZHUVXSSO\PRGXOH 5DWHGLQSXWYROWDJH
RISRZHUVXSSO\
5DWHGLQSXWYROWDJH
RIGLJLWDOLQSXWV
PS_87H 110/120/220/240 V ac
or 110/125/220 V dc DI1...DI8: 110/125/220 V dc DI9: 24/48/60/110/125/220 V dc
PS_87L 24/48/60 V dc DI1...DI9: 24/48/60/110/125/220 V dc
5DWHGLQSXWYROWDJH /RZLQGLFDWLRQOHYHO
PS_87H
•Rated input voltage 110/125/ 220 V dc 99 V dc
•Rated input voltage 110/120/220/ 240 V ac 88 V ac
PS_87L
•Rated input voltage 24/48/60 V dc 21.6 V dc

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 2YHUWHPSHUDWXUHLQGLFDWLRQ
The REX protection relay includes an internal temperature supervision function.
The CPU module issues an internal alarm signal when overtemperature has been
detected inside the relay enclosure. The alarm signal will be activated once the
temperature inside the relay enclosure increases approximately to +78oC. The
overtemperature indication can be seen on the HMI or as an event via serial
communication. The relay will go to the IRF (internal relay fault) state. See
Table 4.1.11.2-1, “Fault indications,”on page 25.
 $QDORJXHFKDQQHOV
The protection relay measures the analogue signals needed for protection,
measuring, etc. via galvanically separated matching transformers. In addition,
currentsensors (Rogowski coil) andvoltage dividers developed by ABB can beused
with REX 521.
The different versions of REX 521 are provided with the following matching
transformers and sensor inputs:
A letter in the order number specifies whether the protection relay is equipped with
basic, medium, high orsensor measuringinput modules.(Refer to section “Ordering
information”on page 48).
 6FDOLQJWKHUDWHGYDOXHVRIWKHSURWHFWHGXQLWIRUDQDORJXH
FKDQQHOV
A separate scaling factor can be set for each analogue channel. The factors enable
differences between the ratings of the protected unit and those of the measuring
device (CTs, VTs etc.) The setting value 1.00 means that the rated value of the
protected unit is exactly the same as that of the measuring device.
When scaling factors are used, it should be noted that they affect the
operation accuracy of the relay. The accuracies stated in the description of
each function block (in the CD-ROM 7HFKQLFDO'HVFULSWLRQVRI)XQFWLRQV)
only applywith the default values ofthe scaling factors.For example, a high
factor affects the operation of sensitive protection functions such as the
directional earth fault protection. To ensure the proper operation of the
function blocks, it must be checked that the analogue scales (pu scales) of
the phase currents IL1, IL2, and IL3, and correspondingly, the analogue scales
of the phase-to-phase voltages U12, U23, and U31 or phase-to-earth voltages
U1,U2,and U3are identical.
9HUVLRQ 0DWFKLQJWUDQVIRUPHUV 6HQVRULQSXWV
Basic CT1, CT2, CT3, CT4 -
Medium CT1, CT2, CT3, CT4, CT5, VT1 -
High CT1, CT2, CT3, CT4, CT5, VT1, VT2, VT3, VT4 -
Sensor CT4, CT5, VT1 RS1, RS2, RS3, VD1, VD2, VD3
!

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The scaling factor is calculated channel by channel as follows:
Scaling factor = Inmd / Inp, where
Example:
The scaling factors for the analogue channels can be set via the HMI of the
protection relay or with the Relay Setting Tool. The HMI path for the scaling factors
is: Configuration\Protected unit\IL1: scaling, IL2:
scaling...
 7HFKQLFDOGDWDRIWKHPHDVXULQJGHYLFHV
The technical data of the measuring devices is set using the Relay Setting Tool or
via HMI. The set values (Configuration\Meas.devices\) will affect the
measurements carried out by REX 521.
9DOXHVWREHVHWIRUDFXUUHQWWUDQVIRUPHU
•rated primary current (1...6000 A) of the current transformer
•rated secondary current (5 A, 2 A, 1 A, 0.2 A) of the current transformer
•rated current (5 A, 1 A, 0.2 A) of the current measuring input (= rated current of
the matching transformer of the protection relay)
•amplitude correction factor (0.9000...1.1000) of the current transformer at rated
current
•correction parameter for the phase displacement error of the current transformer
at rated current (-5.00°...0.00°)
•amplitude correction factor of the current transformer at a signal level of 1% of
the rated current (0.9000...1.1000)
•correction parameter for the phase displacement error of the current transformer
at a signal level of 1% of the rated current (-10.00°...0.00°)
9DOXHVWREHVHWIRUDYROWDJHWUDQVIRUPHU
•rated voltage of primary voltage transformer (0.100...440.000 kV)
•rated voltage of voltage input (same as the secondary rated voltage of the primary
voltage transformer connected to the voltage input, 100 V, 110 V, 115 V, 120 V)
•amplitude correction factor of the primary voltage transformer voltage at rated
voltage (0.9000...1.1000)
•correction parameter for the primary transformer phase displacement error at
rated voltage (-2.00°...2.00°)
Inmd Rated primary current [A] of the measuring device
Inp Rated primary current [A] of the protected unit connected to the
channel
Rated primary current of current trafo = 500 A: Inmd = 500 A
Rated current of the protected unit = 250 A: Inp = 250 A
Scaling factor for current channels: 500 A / 250 A = 2.00

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9DOXHVWREHVHWIRUDFXUUHQWVHQVRU5RJRZV LFRLO
•secondary rated voltage of the current sensor used at the preset primary rated
current (100...300 mV)
•primary rated current of the current sensor used (1...6000 A)
•amplitude correction factor of the current sensor used at rated current
(0.9000...1.1000)
•correction parameter for the phase displacement error of the current sensor
(-1.0000°...1.0000°)
9DOXHVWREHVHWIRUDYROWDJHGLYLGHU
•division ratio of the voltage divider primary and secondary voltage (100...20000)
•rated value of primary phase-to-phase voltage (0.100...440.000 kV)
•amplitude correction factor of the voltage divider (0.9000...1.1000)
•correction parameter for the phase displacement error of the voltage divider
(-1.0000°...1.0000°)
&DOFXODWLRQRIFRUUHFWLRQSDUDPHWHUVDQGIDFWRUV
The measurement values stated by the manufacturer of the measuring device are
used for calculating thecorrection parametersand factors according to the following
formulas:
&XUUHQWWUDQVIRUPHUV
9ROWDJHWUDQVIRUPHUV
5RJRZV LFRLO
Amplitude error at current In
(p = error in per cent)
Amplitude correction factor 1
= 1 / (1+ p/100)
Amplitude error at current 0.01 x In
(p = error in per cent)
Amplitude correction factor 2
= 1 / (1+ p/100)
Phase displacement error at current In
(d = error in degrees)
Phase displacement error 1 = - d
Phase displacement error at current 0.01 x In
(d = error in degrees)
Phase displacement error 2 = - d
Amplitude error at voltage Un
(p = error in per cent)
Amplitude correction factor
= 1 / (1+ p/100)
Phase displacement error at voltage Un
(d = error in degrees)
Phase displacement error = - d
Amplitude error at the whole measuring range
(e = error in per cent) Amplitude correction factor
= 1/(1+ e/100)
Phase displacement error at the whole
measuring range
(e = error in degrees)
Phase displacement error = - e

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9ROWDJHGLYLGHU
 'LJLWDOLQSXWV
The digital inputs of the protection relay are voltage-controlled and optically
isolated. For technical data of the digital inputs, refer to Table 4.2.1-3 on page 37.
 )LOWHULQJRIGLJLWDOLQSXWV
The filter time eliminates debounces and short disturbances on digital inputs. The
filter time may be set individually for each input.
)LJ )LOWHULQJRIDGLJLWDOLQSXW
The figure above illustrates the input filtering. At the beginning, the input signal is
at high state, the first low state is filtered and no input status change is detected. The
second low state is longer than the set filter time, thus detected as a change and
attached with the time tag t0.When the input signal returns to high state, after the
filter time, the state is accepted and attached with the time tag t1.
Each digital input has a filter time parameter Input # filter
(Configuration\Digital inputs\Input filtering), where # is the
number of the input.
A risk fordebounces and short disturbances on digital inputsgrows if the input filter
time is changed to less than the default value.
Amplitude error at the whole measuring range
(e = error in per cent) Amplitude correction factor
= 1/(1+ e/100)
Phase displacement error at the whole
measuring range
(e = error in degrees)
Phase displacement error = - e
7DEOH )LOWHUWLPHSDUDPHWHU
3DUDPHWHU 9DOXHV 'HIDXOW
Input # filter 1...65535 ms 5 ms
t0t1
dipo_rex
Filter Time
Filtered Input
Input
Filter Time
Filter

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 QYHUVLRQRIGLJLWDOLQSXWV
The status of digital inputs can be inverted with parameters accessible through the
HMI or the Relay Setting Tool (Configuration\Digital inputs\Input
inversion). When inverted, the status of a digital input is TRUE (1) when no
control voltage is applied to the terminals, and FALSE (0) when the control voltage
is applied.
 2XWSXWV
The outputs are categorized as follows:
•HSPO: High speed power output, single or double pole contact, for example for
tripping purposes
•PO: Power output, single pole contact
•SO: Signal output, NO/NC (Normally open/Normally closed) contact
For detailed information about terminal connections, refer to the terminal diagrams.
Technical data of the outputs is found in the section “Technical data”on page 37.
 +LJKVSHHGSRZHURXWSXW+632
The high-speed power output HSPO1 can be connected as a double-pole output
where the object to be controlled (for example a circuit breaker) is electrically
connected between the two relay contacts, see theFigure 4.1.8.1.-1 below. The high-
speed double-pole power output is recommended to be used for tripping purposes.
Cbcoilrex
)LJ +LJKVSHHGGRXEOHSROHSRZHURXWSXW+632
The high-speed power output HSPO1 can also be connected as a single-pole power
output wherethe object to be controlled (for example a circuitbreaker) iselectrically
connected in series with the two relay contacts, see the Figure 4.1.8.1.-2 below.
+
-
HSPO1
CB

20
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doubpolerex
)LJ +LJKVSHHGVLQJOHSROHSRZHURXWSXW+632
 6LQJOHSROHSRZHURXWSXWV32
The single-pole power outputs PO1...3 are outputs where the object to be controlled
is connected in series with two heavy-duty output relay contacts, see the Figure
4.1.8.2.-1 below. These outputs can be used for tripping purposes and for circuit
breaker and disconnector control. Two singe-pole outputs may be used to obtain
another double-pole output.
PO1connrex
)LJ 6LQJOHSROHSRZHURXWSXWV32 
 6LJQDOOLQJRXWSXWV62
The signalling relay outputs (SO1 and SO2) are not heavy-duty outputs and thus
they cannot be used for controlling, for example, a circuit breaker. Available relay
contacts are Normally Open/Normally Closed type (NO/NC), see the Figure
4.1.8.3.-1 below. These outputs can be used for alarming and other signalling
purposes.
NoncRex
)LJ  6LJQDOOLQJRXWSXW62
+
-
CB
HSPO1
+
-
CB
PO1...3
O/ C
e.g.
SO1