Siemens 7SR242 Duobias Operating manual

7SR242 Duobias Commissioning & Maintenance Guide
The copyright and other intellectual property rights in this document, and in any model or article produced from it
(and including any registered or unregistered design rights) are the property of Siemens Protection Devices
Limited. No part of this document shall be reproduced or modified or stored in another form, in any data retrieval
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While the information and guidance given in this document is believed to be correct, no liability shall be accepted
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negligence or any other cause. Any and all such liability is disclaimed.
©2010 Siemens Protection Devices Limited
7SR242 Duobias
Multi-Function 2-Winding Transformer Protection Relay
Document Release History
This document is issue 2010/02. The list of revisions up to and including this issue is:
2010/06 Defect Report Form revised
2010/02 Document reformat due to rebrand
2010/02 Third issue. Software revision 2662H80001 R4c-3
2008/07 Second issue. Software revision 2662H80001R3d-2c.
2008/05 First issue
Software Revision History
2010/02 2662H80001 R4c-3 Revisions to: VT ratio settings, 87BD 1st bias slope limit setting
increments, CB fail function, LED CONFIG menu, DATA STORAGE
menu.
Added: Open circuit detection (46BC), CONTROL MODE menu,
Close circuit supervision (74CCS), Measured earth fault undercurrent
(37G), Pulsed output contacts.
2008/07 2662H80001R3d-2c. Demand metering. Optional DNP3.0 data comms.
2008/05 2662H80001R3-2b First Release

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Contents
Document Release History....................................................................................................................1
Software Revision History.....................................................................................................................1
Contents..................................................................................................................................................2
Section 1: Common Functions .............................................................................................................5
1.1 Overview ...................................................................................................................................5
1.2 Before Testing...........................................................................................................................5
1.2.1 Safety ...........................................................................................................................5
1.2.2 Sequence of Tests .......................................................................................................5
1.2.3 Test Equipment ............................................................................................................6
1.2.4 Precautions ..................................................................................................................6
1.2.5 Applying Settings .........................................................................................................7
1.3 Tests .........................................................................................................................................8
1.3.1 Inspection .....................................................................................................................8
1.3.2 Secondary Injection Tests............................................................................................8
1.3.3 Primary Injection Tests.................................................................................................8
1.3.4 Putting into Service ......................................................................................................8
1.4 AC Energising Quantities..........................................................................................................9
1.5 Binary Inputs ...........................................................................................................................10
1.6 Binary Outputs ........................................................................................................................11
1.7 Relay Case Shorting Contacts................................................................................................11
Section 2: Protection Functions.........................................................................................................12
2.1 Biased Differential (87BD, 87HS) ...........................................................................................14
2.1.1 Secondary Injection Testing.......................................................................................14
2.1.2 Primary Injection Testing............................................................................................17
2.1.3 Phase Overcurrent (50, 51)........................................................................................18
2.1.4 Definite Time Overcurrent (50) ...............................................................................19
2.1.5 Inverse Time Overcurrent (51).................................................................................19
2.2 Derived Earth fault (50N,51N).................................................................................................21
2.2.1 Definite Time Overcurrent (50N).............................................................................22
2.2.2 Inverse Time Overcurrent (51N) ..............................................................................22
2.2.3 ANSI Reset.................................................................................................................23
2.3 Measured Earth fault (50G, 51G)............................................................................................24
2.3.1 Definite Time Overcurrent (50G).............................................................................25
2.3.2 Inverse Time Overcurrent (51G) ..............................................................................25
2.3.3 ANSI Reset.................................................................................................................26
2.4 Restricted Earth fault (64H) ..................................................................................................27
2.5 Open Circuit (46BC)..............................................................................................................29
2.6 Negative Phase Sequence Overcurrent (46NPS) ..................................................................31
2.6.1 Definite Time NPS Overcurrent (46DT) ..................................................................32
2.6.2 Inverse Time NPS Overcurrent (46IT) .....................................................................32
2.7 Undercurrent (37, 37G).........................................................................................................34
2.7.1 37-n Elements ............................................................................................................34
2.7.2 37G-n Elements .........................................................................................................35
2.8 Thermal Overload (49)............................................................................................................36
2.9 Under/Over Voltage (27/59)...................................................................................................38
2.9.2 Undervoltage Guard (27/59UVG) ..............................................................................40
2.10 Neutral Over Voltage (59N) ..................................................................................................41
2.10.1 Definite Time (59NDT) ...............................................................................................42
2.10.2 Inverse Time (59NIT) .................................................................................................42

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2.11 Under/Over Frequency (81) ....................................................................................................43
2.12 Overfluxing (24) ......................................................................................................................45
2.12.1 definite time (24DT)....................................................................................................45
2.12.2 inverse time (24IT) .....................................................................................................46
Section 3: Supervision Functions ......................................................................................................47
3.1 CB Fail (50BF) ........................................................................................................................47
3.2 Trip/Close Circuit Supervision (74TCS, 74CCS) ..................................................................49
3.3 Magnetising Inrush Detector (81HBL2) ................................................................................50
3.4 Overfluxing Detector (81HBL5).............................................................................................52
Section 4: Control & Logic Functions................................................................................................53
4.1 Quick Logic .............................................................................................................................53
Section 5: Testing and Maintenance..................................................................................................54
5.1 Periodic Tests .........................................................................................................................54
5.2 Maintenance............................................................................................................................54
5.3 Troubleshooting ......................................................................................................................54
5.4 Defect Report Form ................................................................................................................56

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List of Figures
Figure 2-1 Biased Differential ...........................................................................................................14
Figure 2-2 Secondary Injection using a Variac...............................................................................15
Figure 2-3 Phase Overcurrent...........................................................................................................18
Figure 2-4 Measured Earth Fault........................................................................................................21
Figure 2-5 Measured Earth Fault........................................................................................................24
Figure 2-6 Restricted Earth Fault.......................................................................................................27
Figure 2-7 Open Circuit........................................................................................................................29
Figure 2-8 Negative Phase Sequence Overcurrent...........................................................................31
Figure 2-9 Undercurrent ......................................................................................................................34
Figure 2-10 Thermal Overload.............................................................................................................36
Figure 2-11 Phase Under/Over Voltage..............................................................................................38
Figure 2-12 Neutral Overvoltage.........................................................................................................41
Figure 2-13 Under/Over Frequency ....................................................................................................43
Figure 2-14 Under/Over Frequency ....................................................................................................45
Figure 3-1 CB Fail.................................................................................................................................47
Figure 3-2 Trip Circuit Supervision ....................................................................................................49
Figure 3-3 Magnetising Inrush Detector ............................................................................................50
Figure 3-4 Magnetising Inrush Detector ............................................................................................52

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Section 1: Common Functions
1.1 Overview
Commissioning tests are carried out to prove:
a) Equipment has not been damaged in transit.
b) Equipment has been correctly connected and installed.
c) Prove characteristics of the protection and settings which are based on calculations.
d) Confirm that settings have been correctly applied.
e) To obtain a set of test results for future reference.
1.2 Before Testing
1.2.1 Safety
The commissioning and maintenance of this equipment should only be carried out by skilled personnel trained in
protective relay maintenance and capable of observing all the safety precautions and regulations appropriate to
this type of equipment and also the associated primary plant.
Ensure that all test equipment and leads have been correctly maintained and are in good condition. It is
recommended that all power supplies to test equipment be connected via a Residual Current Device (RCD),
which should be located as close to the supply source as possible.
The choice of test instrument and test leads must be appropriate to the application. Fused instrument leads
should be used when measurements of power sources are involved, since the selection of an inappropriate range
on a multi-range instrument could lead to a dangerous flashover. Fused test leads should not be used where the
measurement of a current transformer (C.T.) secondary current is involved, the failure or blowing of an instrument
fuse or the operation of an instrument cut-out could cause the secondary winding of the C.T. to become an open
circuit.
Open circuit secondary windings on energised current transformers are a hazard that can produce high voltages
dangerous to personnel and damaging to equipment, test procedures must be devised so as to eliminate this risk.
1.2.2 Sequence of Tests
If other equipment is to be tested at the same time, then such testing must be co-ordinated to avoid danger to
personnel and/or equipment.
When all cabling and wiring is completed, a comprehensive check of all terminations for tightness and compliance
with the approved diagrams must be carried out. This can then be followed by the insulation resistance tests
which, if satisfactory allows the wiring to be energised by either the appropriate station supply or test supply.
When primary injection tests are completed satisfactorily, all remaining systems can be functionally tested before
the primary circuit is energised. Some circuits may require further tests before being put on load.
Protection relay testing will require access to the protection system wiring diagrams, relay configuration
information and protection settings. The following sequence of tests is loosely based on the arrangement of the
relay menu structure. A test log based on the actual tests completed should be recorded for each relay tested. A
typical example of this Site Test Sheet is included.
The ‘Description of Operation’ section of this manual provides detailed information regarding the operation of
each function of the relay.

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1.2.3 Test Equipment
Required test equipment is:
Secondary injection equipment with integral time interval meter
Primary injection equipment
A d.c. supply with nominal voltage within the working range of the relay's d.c. auxiliary supply rating
A d.c. supply with nominal voltage within the working range of the relay’s d.c. binary input rating
Other equipment as appropriate to the protection being commissioned – this will be specified in the product
specific documentation.
The secondary injection equipment should be appropriate to the protection functions to be tested. Additional
equipment for general tests and for testing the communications channel is:
•Portable PC with appropriate interface equipment.
•Printer to operate from the above PC (Optional).
Use of PC to facilitate testing
The functions of ReyDisp Evolution (see Section 2: Settings and Instruments) can be used during the
commissioning tests to assist with test procedures or to provide documentation recording the test and test
parameters. One method is to clear both the waveform and event records before each test is started, then, after
the test upload from the relay the settings, events and waveform files generated as a result of application of the
test. These can then be saved off to retain a comprehensive record of that test.
Relay settings files can be prepared on the PC (offline) or on the relay before testing commences. These settings
should be saved for reference and compared with the settings at the end of testing to check that errors have not
been introduced during testing and that any temporary changes to settings to suit the test process are returned to
the required service state.
A copy of the Relay Settings as a Rich Text Format (.rtf) file suitable for printing or for record purposes can be
produced from ReyDisp as follows. From the File menu select Save As, change the file type to Export
Default/Actual Setting (.RTF) and input a suitable filename.
When testing is completed the event and waveform records should be cleared and the settings file checked to
ensure that the required in-service settings are being applied.
1.2.4 Precautions
Before electrical testing commences the equipment should be isolated from the current and voltage transformers.
The current transformers should be short-circuited in line with the local site procedure. The tripping and alarm
circuits should also be isolated where practical. The provision and use of secondary injection test sockets on the
panel simplifies the isolation and test procedure.
Ensure that the correct auxiliary supply voltage and polarity is applied. See the relevant scheme diagrams for the
relay connections.
Check that the nominal secondary current rating of the current and voltage transformers has been correctly set in
the System Config menu of the relay.

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1.2.5 Applying Settings
The relay settings for the particular application should be applied before any secondary testing occurs. If they are
not available then the relay has default settings that can be used for pre-commissioning tests. See the Relay
Settings section of this manual for the default settings.
Note that the tripping and alarm contacts for any function must be programmed correctly before any scheme tests
are carried out.
The relay features multiple settings groups, only one of which is active at a time. In applications where more than
one settings group is to be used it may be necessary to test the relay in more than one configuration.
Note. One group may be used as a ‘Test’ group to hold test-only settings that can be used for regular
maintenance testing, eliminating the need for the Test Engineer to interfere with the actual in-service settings in
the normally active group. This Test group may also be used for functional testing where it is necessary to disable
or change settings to facilitate testing.
When using settings groups it is important to remember that the relay need not necessarily be operating
according to the settings that are currently being displayed. There is an ‘active settings group’ on which the relay
operates and an ‘edit/view settings group’ which is visible on the display and which can be altered. This allows the
settings in one group to be altered from the relay fascia while the protection continues to operate on a different
unaffected group. The ‘Active Settings Group’ and the ‘Edit Settings Group’ are selected in the ‘System
Configuration Menu’.
The currently Active Group and the group currently Viewed are shown at the top of the display in the Settings
display screen. If the View Group is not shown at the top of the display, this indicates that the setting is common
to all groups. CT/VT ratio, I/O mapping and other settings which are directly related to hardware are common to
all groups.
If the relay is allowed to trip during testing then the instruments display will be interrupted and replaced by the
‘Trip Alert’ screen which displays fault data information. If this normal operation interferes with testing then this
function can be temporarily disabled for the duration of testing by use of the Trip Alert Enabled/Disabled setting in
the System Config Menu.
After applying a settings change to the relay, which may involve a change to the indication and output contacts,
the TEST/RESET key should be pressed to ensure any existing indication and output is correctly cleared.

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1.3 Tests
1.3.1 Inspection
Ensure that all connections are tight and correct to the relay wiring diagram and the scheme diagram. Record any
deviations. Check that the relay is correctly programmed and that it is fully inserted into the case. Refer to
‘Section 2: Settings and Instruments’ for information on programming the relay.
1.3.2 Secondary Injection Tests
Select the required relay configuration and settings for the application.
Isolate the auxiliary D.C. supplies for alarm and tripping from the relay and remove the trip and intertrip links.
Carry out injection tests for each relay function, as described in this document
For all high current tests it must be ensured that the test equipment has the required rating and stability and that
the relay is not stressed beyond its thermal limit.
1.3.3 Primary Injection Tests
Primary injection tests are essential to check the ratio and polarity of the current transformers as well as the
secondary wiring. Primary injection testing of the 87BD Biased Differential protection is recommended to avoid
relay operation during first energisation of the transformer if incorrect values are applied to the ICT Connection
protection setting.
Note. If the current transformers associated with the protection are located in power transformer bushings it may
not be possible to apply test connections between the current transformer and the power transformer windings.
Primary injection is needed however, to verify the polarity of the CTs. In these circumstances primary current
must be injected through the associated power transformer winding. It may be necessary to short circuit another
winding in order to allow current to flow. During these primary injection tests the injected current is likely to be
small due to the impedance of the transformer.
Phase current transformer polarities and connections can be checked by examination of the relay Current Meters
and Differential Meters in the Instruments Menu when the protected plant is carrying load but Earth Fault CT
polarity can only be checked during primary injection.
1.3.4 Putting into Service
After tests have been performed satisfactorily the relay should be put back into service as follows:-
Remove all test connections.
Replace all secondary circuit fuses and links, or close m.c.b.
Ensure the Protection Healthy LED is on, steady, and that all LED indications are correct. If necessary press
CANCEL until the Relay Identifier screen is displayed, then press TEST/RESET to reset the indication LEDs.
The relay meters should be checked in Instruments Mode with the relay on load
The relay settings should be downloaded to a computer and a printout of the settings produced. The installed
settings should then be compared against the required settings supplied before testing began. Automated setting
comparison can be carried out by ReyDisp using the Compare Settings Groups function in the Edit menu. Any
modified settings will be clearly highlighted.

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1.4 AC Energising Quantities
Voltage and current measurement for each input channel is displayed in the Instrumentation Mode sub-menus,
each input should be checked for correct connection and measurement accuracy by single phase secondary
injection at nominal levels. Ensure that the correct instrument displays the applied signal within limits of the
Performance Specification.
Applied Current Applied
Voltage
W1-IA W1-IBW1-ICI
G1 W2-IA W2-IBW2-ICI G2 V 1(VX)
Secondary
Primary
Apply 3P balanced Current at nominal levels and ensure that the measured Zero Phase Sequence and Negative
Phase Sequence quantities are approximately zero.
ZPS NPS
Current

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1.5 Binary Inputs
The operation of the binary input(s) can be monitored on the ‘Binary Input Meters’ display shown in ‘Instruments
Mode’. Apply the required supply voltage onto each binary input in turn and check for correct operation.
Depending on the application, each binary input may be programmed to perform a specific function; each binary
should be checked to prove that its mapping and functionality is as set as part of the Scheme Operation tests.
Where the pick-up timers associated with a binary input are set these delays should be checked either as part of
the scheme logic or individually. To check a binary pick-up time delay, temporarily map the binary to an output
relay that has a normally open contact. This can be achieved in the Output Matrix sub-menu by utilising the BI n
Operated settings. Use an external timer to measure the interval between binary energisation and closure of the
output contacts. Similarly, to measure the drop-off delay, map to an output relay that has a normally closed
contact, time the interval between binary de-energisation and closure of the output contacts.
Note. The time measured will include an additional delay, typically less than 20ms, due to the response time of
the binary input hardware, software processing time and the operate time of the output relay.
BI Tested DO
Delay
Measure
d
PU
Delay
Measured Notes (method of initiation)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

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1.6 Binary Outputs
A minimum of six output relays are provided. Two of these have change over contacts, BO2 & BO3, one has a
normally closed contact, BO1 and the remainder have normally open contacts.
Care should be observed with regard to connected devices when forcing contacts to operate for test purposes.
Short duration energisation can cause contact failure due to exceeding the break capacity when connected to
inductive load such as electrically reset trip relays.
Close each output relay in turn from the ReyDisp Evolution PC programme, Relay – Control - Close output relay.
This function will energise the output for its minimum operate time. This time is specified in the Output Config -
Binary Output Config menu for each output relay and may be too short to measure with a continuity tester.
An alternative method of energising an output permanently so that wiring can be checked is to temporarily map
the relay being tested to the ‘Protection Healthy’ signal in the Output Matrix, as this signal is permanently
energised the mapped relay will be held energised, normally open contacts will be closed and vice versa.
BO Checked Notes (method of test)
1NC
2NO
2NC
3NO
3NC
4
5
6
7
8
9
10
11
12
13
14
1.7 Relay Case Shorting Contacts
CT inputs and terminals C25-C26 (Relay Withdrawn Alarm) are fitted with case mounted shorting contacts which
provide a closed contact when the relay is withdrawn from the case. The operation of these contacts should be
checked.
CT Shorting contacts checked
Relay Withdrawn Alarm Checked

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Section 2: Protection Functions
This section details the procedures for testing each protection function of the 7SR24 relay. These tests are carried
out to verify the accuracy of the protection pick-ups and time delays at setting and to confirm correct operation of
any associated input and output functionality.
Guidance for calculating test input quantities is given in the relevant test description where required. In many
cases it may be necessary to disable some functions during the testing of other functions, this prevents any
ambiguity caused by the operation of multiple functions from one set of input quantities. The ‘Function Config’
Menu provides a convenient high level point at which all elements of a particular function can be
Enabled/Disabled to suit testing. The ‘Config’ tab in ‘ReyDisp Evolution’ can be used to ‘Enable/Disable’ individual
elements. Note that this screen disables functions by applying setting changes to the relay and that any changes
must be sent to the relay to take effect and settings must be returned to their correct value after testing.
The table below indicates functions where function conflicts may occur during testing, consideration should be
given to disabling functions to avoid interference.
Function
Under
Test
Biased Differential
Differential Highset
Phase Overcurrent
Derived E/F
Measured E/F
Restricted E/F
Open Circuit
NPS Overcurrent
Undercurrent
Thermal
U/O voltage
Neutral Overvoltage
U/O Frequency
Overfluxing
CB Fail
Trip cct Supervision
Inrush Detector
Overfluxing Detector
Biased Diff. OOOOOOOOO O
Diff. Hi
g
hset O OOOOOO O
Phase OC O O OO OOOO O
Derived E/F O O O OOOOOO O
Measured E/F O O O O OOOOO O
Restricted E/F O O O O O OOOO O
Open Circuit O O O O OO O
NPS OC O O O O O OO O
Undercurrent O O O O O O O O
Thermal O O O O O O O O
U/O volta
g
e O O O O
Neutral OV O O O
U/O Frequenc
y
O O
Overfluxin
g
OO O
CB Fail O O O O O O O O O O O O O O
74TCS/74CCS
Inrush Detecto
r
O/fluxin
g
Detecto
r
The General Pickup LED can be used to assess operation of functions during testing if other functions are
disabled or if the setting allocating General Pickup is temporarily modified.
Particular care should be taken when testing overcurrent functions that the thermal rating of the current inputs is
not exceeded.

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It should be considered that where several overlapping elements are used simultaneously, the overall protection
operate time may be dependent on the operation of different individual elements at the various levels of applied
current or voltage. The resulting composite characteristic may be tested by enabling all of the relevant applicable
elements or the element operations can be separated or disabled and tested individually.
All relay settings should be checked before testing begins. It is recommended that the relay settings are extracted
from the relay using ReyDisp Evolution software and a copy of these settings is stored for reference during and
after testing. It may be necessary to disable some protection functions during the testing of other functions to
allow unambiguous results to be obtained.
Care must be taken to reset or re-enable any settings that have been temporarily altered during the testing before
the relay can be put into service. At the end of testing the relay settings should be compared to the file extracted
at the start to ensure that errors have not been introduced.
An example ‘Test Sheet’ summary document is included at the end of this Guide.

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2.1 Biased Differential (87BD, 87HS)
Figure 2-1 Biased Differential
Voltage Inputs: None
Current Inputs: W1-IL1 (IA),W1-IL2 (IB),W1-IL3 (IC), and W2-IL1 (IA),W2-IL2 (IB),W2-IL3 (IC),
Disable: 46, 49, 50, 51, 50N, 51N, 50BF,
Map Pickup LED: 87BD, 87HS - Self Reset
The differential elements are subjected to CT multipliers, Vector Group Compensation and Zero Sequence filters
when applied to power transformers. The complexity of these features can cause confusion during testing and
lead to incorrect relay settings being applied. It is recommended that the accuracy of the differential elements are
tested by secondary injection with simplified differential settings applied to avoid ambiguity before reinstating the
required site settings which can be tested more thoroughly by primary injection followed by final checking with the
protected transformer on load.
2.1.1 Secondary Injection Testing
The settings used for Secondary Injection test purposes should be:
W1ICTMultiplier1x W1ICT
Connection Yy0,0deg W2 ICT
Multiplier 1x W2ICT
Connection Yy0,0deg

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Secondary testing of the bias characteristic will be greatly simplified by the use of automated numeric protection
test equipment such as the Omicron CMC256. This equipment can be programmed using setting which match
those of the relay to test for accuracy over the whole operating range and give a clear easy to use graphical
display of relay performance against the specified characteristic.
The relay characteristic can however be tested manually by recording a sequence of operating points for
increasing levels of Restrain current. This can be achieved phase by phase using a single current source such as
a Variac with two independently variable current limiting resistors as shown in figure 2-2 or from two independent
single or three phase current sources.When two separate sources are used the phase of the two sinusoidal
supplies must be the same and the Restrain and Operate currents must be calculated from the sum and
difference of the two currents.
During manual testing the Operate and Restrain currents can be monitored on the relay in the Differential Meters
in the Instruments menu.
For manual testing, the bias slope is usually checked for Restrain current up to 250% of nominal current. For
testing above this level the continuous current rating of the relay inputs is likely to be exceeded, equipment or test
procedure should be arranged in such a way that the short term thermal withstand of the relay current inputs is
not exceeded during testing.
Figure 2-2 Secondary Injection using a Variac
2.1.1.1 Results for testing 87BD with a Variac BIAS CURRENT (X IN)
MEASURED ON AMMETER A1
0.00 1.00 1.50 2.00 2.50
87BD INITIAL
SETTING 87BD 1ST BIAS SLOPE SETTING
Operate Current Measured on Ammeter A2
0.10 0.10 0.10 0.11 0.16 0.21 0.26
0.20 0.20 0.20 0.22 0.33 0.44 0.56
0.30 0.30 0.30 0.35 0.53 0.71 0.88
0.40 0.40 0.40 0.50 0.75 1.00 1.25
0.50 0.50 0.50 0.67 1.00 1.33 1.67
0.50 0.60 0.50 0.86 1.29 1.71 2.14
0.50 0.70 0.50 1.08 1.62 2.15 2.69
Selected Settings Test Results
0.00 1.00 1.50 2.00 2.50
Phase A Pickup
Phase B Pickup
Phase C Pickup

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2.1.1.2 Results for testing 87BD with 2 current sources
W1 CURRENT (X IN)
0.00 1.00 1.50 2.00 2.50
87BD INITIAL
SETTING 87BD 1ST BIAS SLOPE SETTING
W2 Current (x In)
0.10 0.10 0.1 1.11 1.66 2.21 2.76
0.20 0.20 0.2 1.22 1.83 2.44 3.06
0.30 0.30 0.3 1.35 2.03 2.71 3.38
0.40 0.40 0.4 1.5 2.25 3.0 3.75
0.50 0.50 0.5 1.67 2.5 3.33 4.17
0.50 0.60 0.5 1.86 2.79 3.71 4.64
0.50 0.70 0.5 2.08 3.12 4.15 5.19
Selected Settings Test Results
0.00 1.00 1.50 2.00 2.50
Phase A Pickup
Phase B Pickup
Phase C Pickup
2.1.1.3 Differential Highset 87HS
Differential Highset can be tested by single phase secondary current injection. 87HS settings will usually be
higher than the continuous thermal rating of the relay current inputs and equipment or test procedure should be
arranged in such a way that the short term thermal withstand of the relay current inputs is not exceeded during
testing. 50% of relay setting current can be injected into each of the 2 winding inputs simultaneously to achieve a
differential current level of 100% if test current is limited by test equipment capacity.
The settings used for Secondary Injection test purposes should be:
W1ICTMultiplier 1x
W1 ICT Connection Yy0,0deg
W2ICTMultiplier 1x
W2 ICT Connection Yy0,0deg
These settings ensure a 1:1 ratio between the injected current and the relay setting. Note that operation of the
element can be achieved at a lower level of current if a higher ICT multiplier setting is applied.
During testing the Operate current can be monitored on the relay in the Instruments menu.

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2.1.2 Primary Injection Testing
Primary injection is recommended to prove the relay connections, CT polarity and settings before putting the
protection scheme into service. Primary injection is essential to fully prove the connections of the Biased
Differential and REF protections. To provide a useful test the relay should have the final site specific settings
applied for primary injection tests.
WARNING!
It is important before carrying out any primary injection to ensure appropriate CTs are shorted to avoid operation
of mesh corner or busbar type unit protection. If the injected primary current is large enough, the bus zones
protection may operate.
Sufficient primary current to prove the connections and settings is required so that a minimum secondary current
of about 10mA rms circulates in the relay inputs. This is difficult to achieve using high current primary injection
equipment due to the relatively high impedance of the transformer windings. An alternative method is to apply 415
LVAC to one side of the transformer with a short circuit applied to the other side. The external three-phase
primary short is usually applied to the HV side so that the LVAC supply is connected to the winding with lowest
impedance which will result in a higher current level. The test current that will be produced can be predicted
based on the impedance of the transformer and the applied test voltage. The primary test current is injected
through all of the biased differential CT’s on the LV side.
Injection of 3 phase current in this way will simulate balanced load conditions, or through fault. During injection,
check that the W1 and W2 relay currents are in anti-phase by examination of the relay ‘Differential Meters’ in
‘Instruments Mode’. Check each phase in turn, ensuring that the phase angle for ‘W1 Relay’ is in anti-phase with
‘W2 Relay’.
When the transformer is eventually energised and carrying load current, the above examination of the W1 and W2
relay current phase angle should be re-checked for anti-phase to ensure that the correct ICT Connection settings
are applied to the differential protection.
It should be noted that checking of Vector Grouping by phase alignment between W1 and W2 by 3 phase primary
injection or on-load will highlight phase cross-over or connection polarity but will not show incorrect application of
zero sequence filters.

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©2010 Siemens Protection Devices Limited Chapter 6 Page 18 of 57
2.1.3 Phase Overcurrent (50, 51)
Figure 2-3 Phase Overcurrent
Voltage Inputs: None
Current Inputs: W1-IL1 (IA), W1-IL2 (IB), W1-IL3 (IC), or W2-IL1 (IA), W2-IL2 (IB), W2-IL3 (IC),
Disable: 46, 49, 50BF, 87BD, 87HS
Map Pickup LED: 51-n/50-n - Self Reset
Other protection functions may overlap with these functions during testing, it may be useful to disable some
functions to avoid ambiguity.
These elements can be allocated to W1 or W2 current inputs by relay settings, ensure that current is injected on
the correct input.
Particular care should be taken when testing overcurrent functions that the thermal rating of the current inputs is
not exceeded.

7SR242 Duobias Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 19 of 57
2.1.4 Definite Time Overcurrent (50)
If DTL setting is small, gradually increase current until element operates.
If DTL is large apply 0.9x setting, check for no operation, apply 1.1x setting, check operation
Apply 2x setting current if possible and record operating time
Phas
e Dir. Is (Amps) DTL (sec) P.U. Current Amps Operate Time 2 x Is NOTES
IL1(IA)
IL2(IB)
IL3(IC)
Check correct indication, trip output, alarm contacts, waveform record.
2.1.5 Inverse Time Overcurrent (51)
It will be advantageous to map the function being tested to temporarily drive the relevant Pickup output in the
Pickup Config sub-menu in the Output Config menu as this will allow the Pick-up LED to operate for the function.
Gradually increase current until Pickup LED operates.
Apply 2x setting current and record operating time,
Apply 5x setting current and record operating time.
Compare to calculated values for operating times
Operate Current Operate Time
Ph. Dir Char.
(NI EI VI
LTI, DTL)
Is
(A) TM P.U.
(Amps) D.O. (Amps) 2 x Is (sec) 5 x Is (sec)
NOTES
IL1(IA)
IL2(IB)
P.U.
D.O.
&
TIMIN
G
TESTS IL3(IC)
Calculated Timing values in seconds for TM =1.0
Curve 2 xIs 5 xIs
IEC-NI 10.03 4.28
IEC-VI 13.50 3.38
IEC-EI 26.67 3.33
IEC-LTI 120.00 30.00
ANSI-MI 3.80 1.69
ANSI-VI 7.03 1.31
ANSI-EI 9.52 1.30
Note that the operate time may be subject to the Minimum op time setting for the element and/or may have a
Follower DTL applied.

7SR242 Duobias Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 20 of 57
2.1.5.1 Element Blocking
The Phase Overcurrent elements can be blocked by Binary Input Inhibit and Inrush Detector operation. This
functionality should be checked.
Element BI Inhibits Inrush Detector
51-1
51-2
50-1
50-2
2.1.5.2 ANSI Reset
If the element is configured as an ANSI characteristic, it may have an ANSI (decaying) reset delay applied. If
ANSI reset is selected for an IEC characteristic element, the reset will be instantaneous.
ANSI reset times from operated condition to fully reset are as follows for zero applied current and Time multiplier
(TM) = 1.0. The reset curve characteristic type and TM is defined by the operating characteristic.
Curve Fully operated to reset with Zero current applied & TM=1 (secs)
ANSI-MI 4.85
ANSI-VI 21.6
ANSI-EI 29.1
Apply current in the following sequence, a) 2x setting for a time to ensure element operation, b) Zero current for
the reset time above (xTM), c) 2x setting for a time to ensure element operation. Check that the second operation
(c) is similar to the first (a) and in line with the expected operate time for the element at this current level.
Repeat the test with the reset time (b) reduced to 50% of the previous value. Ensure that the second operate time
(c) is 50% of the first (a) operate time.
Check correct indication, trip output, alarm contacts, waveform record.
Operate time
(expected) Reset time (calculated) Operate time (measured) 50% Reset Time
(calculated)
50% operate
time
(calculated)
50% operate
time
(measured)
First test (c) Second Test (c)