1. VISHWAKARMA GOVERNMENT
ENGINEERING COLLEGE, CHANDKHEDA
An IDP
On
Designing Of Alternator Protection Schemes
Guided by Prepared by:-
S.P. Sapre Sir (H.O.D. Elec.) RATHOD NIKUNJSIN D. (120173109007)
PATEL ANIL S. (120173109022)
MODHA HARDIK P. (120173109020)
Industry Defined Project of Design of Alternator
2. Protection
At
Industry Guide:-
Ravi Patel (Project Engineer)
Ravi Unadkat (Project Engineer)
Hardik Patel (Project Engineer)
Snehal Patel (Project Engineer)
Satyam Dave (Project Engineer)
2
4. Industry Guide:-
Rupinder Singh (Regional Application Specialist (MESA) in India)
Aditya Taneja (Engineer-Sales & Application in India)
Hinson Lam (Technical Support HK world wide)
INDEX
1. Preface……………………………………………………………………………...6
4
5. 2. History of Siemens…………………………………………………………….7
3. Siemens Business Segments………………………………………………8
4. Alternator……………………………………………………………………….11
I. General Structure of a generator capability…..11
II. Cylindrical Rotor……………………………………...….11
III. Brushless alternators……………………………….…13
5. Synchronization of Alternator to Infinite Bus-bar……………...15
I. Equality of Voltage………………………………………15
II. Equality of Frequency………………………………….16
III. Phase Sequence…………………………………………...17
IV. Phase Difference Angle (Phase Displacement)18
6. Switch gear & Protection……………………………………..19
7. Protection of Alternator………………………………………………...…24
I. Alternator Faults………………………………………...24
A. Stator Winding Faults…………………………24
B. Field Winding or Rotor Circuit Faults…..24
C. Abnormal Operating Conditions…………..25
8. SIPROTEC 7UM62 RELAY………………………………………………...26
I. Advantages of 7UM62 Relay…………………………27
II. Function of 7UM62 Relay……………………………..28
9. SIPROTEC 7UM62 RELAY Configuration with Alternators…29
10. C.T.& P.T. Connection of 7UM62 Protection Relay……………..30
11. Differential Relay Operation of 7UM62 Relay for Alternator
Protection………………………………………………………………………31
12. Different Fault Setting for 10.4MW Steam –Turbine
Generator……………………………………………………………………….32
13. Brief About Faults in Alternators……………………………………34
14. Automatic Field Suppression and use of Neutral
CircuitBreaker…………………………………………………………………46
15. Problem Associated in 7UM62 Relay………………………….……..47
16. Solution………………………………………………………………………..…48
i. Brief About Solution………………………………………49
PREFACE
It gives me great pleasure to present this Report to the new trainee. My
Report Gives you more visualization and more Information about Turbines,
Alternators and It’s Auxiliaries. Some content is not given in details. There are
Illustrative Figures is given into this Report so you can easily Grasp.
5
6. I am Thankful to Satyam Dave Sir and Ravi Patel Sir (Electrical
Engineering) ,M.H.Makwana(Senior Manager of CPP at ARVIND MILLS) &
Rupider Singh(OMICRN,Delhi), thank you sir for sharing Information and
Knowledge regarding Alternator and It’s Protection System.
I am very very Thankful to Snehal PatelSir (Design Depart.-SIEMENS).
Thank you sir for arranging this Training sessions, giving Opportunity to
improve our skill and updated with today’s World Class Technology and giving
us Confidence.
Siemens & Halske was founded by Werner von Siemens on 12 October 1847. Based
on the telegraph, his invention used a needle to point to the sequence of letters, instead of
using Morse code. The company, then called Telegraphen Bauanstalt von Siemens & Halske,
opened its first workshop on October 12.
6
7. In 1881, a Siemens AC Alternator driven by a watermill was used to power the
world's first electric street lighting in the town of Godalming, United Kingdom. The company
contin light bulbs. In 1890, the founder retired and left the company to his brother Carl and
sons Arnold and Wilhelm. Siemens & Halske (S & H) was incorporated in 1897, and then
merged parts of its activities with Schuckert & Co., Nuremberg in 1903 to become Siemens -
Schuckert.
In 1907, Siemens (Siemens & Halske and Siemens 34,324 employees and was the
seventh -largest company in the German empire by number of employees. (seeList of
German companies by1907)
In March 2011, it was decided to list Osram on the stock market in the autumn, but
CEO Peter Loöscher said Siemens intended to retain a long-term interest in the company,
which was already independent from the technological and managerial viewpoints
In September 2011 Siemens, which had been responsible for constructing all 17 of
Germany's existing nuclear power plants, announced that it would exit the nuclear sector
following the Fukushima disaster and the subsequent changes to German energy policy.
Chief executive Peter Loescher has supported the German government's planned
Energiewende, its transition to renewable energy technologies, calling it a "project of the
century" and saying Berlin's target of reaching 35% renewable energy sources by 2020 was
feasible
The Business Segment
The business of Siemens is divided into four different segments (also called as sectors).
Siemens and its subsidiaries employ approximately 360,000 people across nearly 190 countries
and reported global revenue of approx. 73.5 billion Euros for the year of 2011. The sectors are as
follows.
Energy
Healthcare
Industry
Infrastructure and Cities.
Energy Sector
Siemens consolidates its innovative offerings in the Energy sector by combining its
full range expertise in the areas of Power Generation (PG) and Power
Transmission & Distribution (PTD). Utilizing the most advanced plant diagnostics
and systems technologies, Siemens provides comprehensive services for complete
power plants and for rotating machines such as gas and steam turbines, generators
and compressors.
Power Generation Special Applications
Gas Turbines Fans
Steam Turbines Mechanical Drives
Generators Services
7
8. Power Plants Expansion Turbines
Renewables Compressor Packages
Environmental Systems
Fuel Gasifier
Power Transmission
Power Distribution
Automation, Controls, Protection & Electricals
Compression, Expansion & Ventilation
Turbo compressors
The Siemens Plant inManeja, Vadodara manufacture the steam turbine, the Condenser unit and
the Designing of the power plant for controlling the turbine and Designing Alternator and It’s
Auxiliaries component in the power plant
8
Energy Oil and Gas Steam Unit Gas Turbine
Sales
Marketing
Project
Engineering
Core
Engineering
Project
Management
B.O.P.(Bill of Project)
Mechanical
B.O.P.(Bill of
Project)Electrical
Lubricating Oil
Mechanism
Electrical Panel Design
M.C.C. Specifications
Turbine
Condenser
SIEMENS
BARODA
9. 1) The Process compressor consists of various parts as,
Project Engineering.
Core Engineering.
2) Project management.
3) The project Engineering consists of B.O.P. (bill of project) of the mechanical as well as
electrical.
4) In the B.O.P. Electrical department the alternator, control panels, M.C.C. Metering Section
etc. are being designed.
5) In the B.O.P. mechanical department the turbine, lubrication, oil mechanism, pump sets,
bearing mechanism, gear box etc. are being designed.
6) Core Engineering consists of the turbine as well as the condenser Technology which is the
base of the total power plant.
7) B.O.P. also consists three things:
9
Steam jet ejection
Bearing
Gearbox
Pump sets
Alternator Specifications
Metering Panel
Single Line Diagram
LA, SC, PT, CT
Neutral Grounding
10. 1. S.L.D. ( Single line diagram )
2. L.A, S.C, C.T. & P.T. (lighting arrestor, Surge Capacitor, Current transformer, potential
transformer )
3. N.G.R. ( Neutral grounding resistance )
The process of the project management has three step are being carried out initially
S.L.D. is being drawn. After it L.A. S.C. C.T. & P.T. being Selected then the N.G.R. is being
selected
Alternator
10
Cylindrical Rotor
Stator
11. An alternator is an electrical generator that converts mechanical energy to electrical energy in the form
of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with
a stationary armature
Smooth cylindrical Rotor
It is used for steam turbine driven alternator. The rotor of this generator rotates in very high speed. The
rotor consists of a smooth solid forged steel cylinder having a number of slots milled out at intervals along
the outer periphery for accommodation of field coils. These rotors are designed mostly for 2 pole or 4 pole
turbo generator running at 3000 rpm or 1800 rpm respectively.
A conductor moving relative to a magnetic field develops an electromotive force(EMF) in it, (Faraday's
Law). This emf reverses its polarity when it moves under magnetic poles of opposite polarity. Typically, a
rotating magnet, called the rotor turns within a stationary set of conductors wound in coils on an iron core,
11
12. called the stator. The field cuts across the conductors, generating an induced EMF (electromotive force), as
the mechanical input causes the rotor to turn.
The rotating magnetic field induces an AC voltage in the stator windings. Since the currents in the stator
windings vary in step with the position of the rotor, an alternator is a synchronous generator.
The rotor's magnetic field produced by a field coil electromagnet.
Alternators used in central power stations also control the field current to regulate reactive power and to
help stabilize the power system against the effects of momentary faults. Often there are three sets of stator
windings, physically offset so that the rotating magnetic field produces a three phase current, displaced by
one-third of a period with respect to each other.
One cycle of alternating current is produced each time a pair of field poles passes over a point on the
stationary winding. The relation between speed and frequency is , where is the
frequency in Hz (cycles per second). is the number of poles (2,4,6...) and is the rotational speed
in revolutions per minute (RPM)
Brushless alternators:-
A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless
alternators may look like one unit but the two parts are readily identifiable on the large versions. The larger
of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field
coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a
rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted
on the rotor. Neither brushes nor slip rings are used, which reduces the number of wearing parts. The main
alternator has a rotating field as described above and a stationary armature (power generation windings).
Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the
exciter. This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC
supplies the rotating field of the main alternator and hence alternator output. The result of all this is that a
small DC exciter current indirectly controls the output of the main alternator.
12
13. PMG: It is a part of the generator excitation system where the rotor of the
PMG is mounted on the main generator extended shaft. Output of the PMG is
connected to Generator AVR Panel.
Space Heaters: They are fitted in the machine to avoid condensation in the event
of long storage, also when machine is not in operation. Care should be
taken such that it is switch on when not in operation, and switch off before the
machine is commissioned into operation.
Cooler: The cooler are used in alternator for its cooling purpose. They provide
cooling by air or by water medium. In CACW (Closed Air and Circulating Water) the
circulating air absorbs the heat loss of the machine and dissipates in to the cooling water
through the heat exchanger/tube bundle.
Fans are assembled on the shaft facilitate the effective cooling by circulating the air
from cold air to hot air & vice versa. There are three types of cooler.
13
14. Top Mounted Cooler
Side Mounted Cooler
Bottom Mounted Cooler
Basic Requirements to Design Alternator:
Ratings
Cooling System
Reactance
Efficiency
Stator (field)
Rotor (armature)
Power Capability Curve
Rotor Heating Limit
Synchronization of Alternator to Infinite Bus bar:-
Synchronization is the process to connect Alternator in Parallel with Infinite Busbar(Grid) which are
connected with no. of Alternators.
For synchronization, following conditions must be satisfied:
(1) EQUALITY OF VOLTAGE
(2) PHASE SEQUENCE
(3) EQUALITY OF FREQUENCY
(4) PHASE Difference Angle
14
15. Voltage:-
Voltage can be checked with the help of Potential Transformer.
If the Alternator Voltage More than Grid Voltage we can equal it by giving less Excitement to Rotor of
Alternator or Vice versa.
SYNCHRONIZING BY SYNCHROSCOPE:
15
16. Frequency:-
If the Frequency of Grid and Alternator is not same there is some resultant voltage is Produced between
them which tends to flow circulating current.
If the Frequency of generator is greater than Grid so by Decreasing speed of rotor or Vice versa. We can get
same Frequency as Grid.
Synchroscope is a device that shows the correct instant of closing the synchronizing switch with the help of
a pointer which will rotate on the dial. The rotation of pointer also indicates whether the incoming machine
is running too slow or too fast.
16
17. If incoming machine is slow then pointer rotates in anticlockwise direction and if machine is fast then
pointer rotates in clockwise direction.
Fig. 3 Synchronizing by Synchroscope
Phase Sequence:-
It is forknowing Three Phase Sequence (R, Y, B or U, V, W) It is forensured to that the three phase (R, Y, B
or U, V, W)of Alternator is connected to Grid three phase. If there is interchanging of R-Y’ instead of R-R’
there is 240o
or 120o
Phase difference which result to voltage difference so the circulating current flow
between them. And it can be measured by Phase Sequence Indicator.
Phase Displacement:-
17
We have to give three phase signal of both P.T. to
this Phase Sequence Indicator.
If the Phase Sequence is(Rg-Ra, Yg-Ya, Bg-Ba)
Correct it will Rotate in a Arrow Direction.
If it rotate in another direction the Phase
Sequence is incorrect (Rg-Ya, Yg-Ra, Bg-Ba) so we
have to interchange Generator terminal.
18. When there is equal Voltage, Frequency and same Phase Sequence but there is small phase
Displacement it can result in a flow of circulating Current between Alternator and Grid.
Forcomplete minimization of Phase displacement We have to see both waveforms then
increase frequency of alternator when it catch the grid voltage phasor then we have to
dercrease it’s frequency to rated frequency.
(Figure of Grid and Alternator phasor diagram)
Note:- InSynchronization of 11 kV Alternator to Grid Tolerance of 10o
is acceptable.
Switch gear & Protection:-
18
Phase Displacement Between two waveform of
Alternator and Grid
The Value of Vg and Va is
Different for time t1
Valternator
Vgrid
t1
Grid Voltage Phasor
Alternator Voltage Phasor
Phase Displacement
19. As a switch gear the Circuit Breaker is used. There are two function of Circuit Breaker
1. It switches ON and OFF the circuit in healthy condition.
2. It breaks the circuit in abnormal condition such as short circuit or fault.
Normal Operation of Power System:-
1. Voltages and currents are balanced i.e. the three-phase voltages are equal and the three-phase
currents are also almost equal.
2. Frequency of the supply is equal to the rated frequency. There is very little change in the
frequency.
3. There is no change in the voltage beyond some limit.
4. Power flow is in the desired direction.
5. Value of current is equal to the rated value or less than it.
Abnormal Condition of power system:-
1. Overloading of Equipment:-
2. Unbalanced loading:-
3. Failure of prime mover in power station
4. Failure of exciter in power Station
5. Loose Contacts
Fault:-
Abnormalities is the result of Fault. It means the defect developed in electrical system due
to which flow of current is diverted from its desired path.
When there is change in voltage, current, frequency, power factor or temperature beyond
some limit, the condition of the power system is called the abnormal condition.
Cause of Fault:-
1. Defect in insulation of the winding of electrical equipment :
i. Ageing
ii. Voltage surge
2. Defect in underground cable :
3. Defect in overhead line :
4. Defect in the bus bars of control panel of the substation :
Various types of Faults occurred in Power System:-
19
20. N
o
Fault Chance
s
1. Over head Fault 50%
(i) Line to Ground Fault 85%
(ii) Line to line Fault 8%
(iii
)
Line to line Ground Fault 5%
(iv) Line to line Fault 2%
2. Underground Cables 10%
3. Switchgear 15%
4. Transformer 12%
5. CT & PT 2%
6. Control Equipment 3%
7. Miscellaneous 6%
Function of a protection System:-
When fault or abnormal condition is produced in power system. The faulty component should be
immediately isolated or should be isolated as quickly as possible from the system because otherwise the
faults spreads in the healthy system and more damage occurs to the system so the reliability becomes
lesser.And there is always Backup Protection is used at Primary Protection.
20
21. If High Voltage or High Current passes through the instrument transformer gives signal to the relay and
relay operates the circuit breaker.
21
22. In a new Trend of Power System there is continuously data transferred of Voltage level, current, frequency,
power factor, active power and reactive power between all the substation of National Grid of India through
Power Line Communication Line so by this PLCC line we can operate any Circuit Breaker.
Functional Requirements of Protection Relay:-
(1) Reliability
The most important requisite of protective relay is reliability. They remain inoperative for a long
time before a fault occurs; but if a fault occurs, the relays must respond instantly and correctly.
(2) Selectivity
It is the ability of the relay to sense the fault in its own zone and to operate the circuit breaker to
isolate the faulty component without affecting other healthy sections which are not in its zone.
(3) Sensitivity
The relaying equipment must be sufficiently sensitive so that it can be operated reliably when level
of fault condition just crosses the predefined limit.
(4) Simplicity
22
23. Relay have to be designed so simple that anyone can interference with them.
(5) Discrimination
The relay should have the power of discrimination which means that it should operate only when fault
occurs in its own zone and should not operate when there is through fault.
Thus it should be capable to sense whether the fault is in its own zone or it is the through fault.
So the relay should be capable to discriminate between overload and Fault.
(6) Speed
The protective relays must operate at the required speed. There must be a correct coordination provided in
various power system protection relays in such a way that for fault at one portion of the system should not
disturb other healthy portion. Fault current may flow through a part of healthy portion since they are
electrically connected but relays associated with that healthy portion should not be operated faster than the
relays of faulty portion otherwise undesired interruption of healthy system may occur.
Zones of Protection:-
23
24. Protection of Alternator:-
Protection of Alternator is the most complex because of following
results:
Alternator is a costly equipment and one of the major links in a power system.
Alternator is not a single equipment but is associated with unit-transformers, auxiliary transformer,
station bus-bars, excitation system, prime mover, voltage regulating equipment, cooling system
etcetera. The protection of alternator, is therefore, to be coordinated with the associated equipment.
The alternator capacity has sharply risen in recent years from 30 MW to 500 MW with the result
that loss of even a single machine may cause overloading of the associated machines in the system
and eventual system instability.
Alternator Faults:-
A. Stator Winding Faults
Such faults occur mainly due to the insulation failure of stator winding coils.
The main types of stator winding faults are
(i) Phase to Earth Faults
(ii) Phase to Phase Faults
(iii) Inter turn Faults inter turn involving turns of same winding.
The stator windings of Big Alternators are hollow copper bars type so stator faults are the most
dangerous faults and also it is very expensive to repair and in some case there is need of
replacement of alternator stator.
There may be to possibility in the above Fault:
(1) Arcing to core, which welds lamination together causing eddy current hot spots on subsequent
use. Repairs to this condition involve expenditure of considerable money and time.
(2) Severe heating in the conductors damaging them and the insulation with possible fire breaks.
B. Field Winding or Rotor Circuit Faults
Faults in the rotor circuit may be either earth faults (conductor to earth faults) or inter turn
faults, which are caused by severe mechanical and thermal stresses.
The faults due to short ckt of rotor core and bits winding not lead to Earth fault but earth fault
will short circuit of rotor winding and may thereby develop an unsymmetrical field system, giving
unbalanced force to rotor. This can cause severe vibration of the rotor with possible damage to Bearing
and may bend the shaft.
Also Failure of Excitation may occur due to open ckt or short ckt in the field. so due to this the
rotor rpm increases and whole machine act as a induction generator and supplying leading power
factor. So there is loss of synchronism as bad as system stability.
24
25. C. Abnormal Operating Conditions
1. Failure of prime mover resulting in synchronous motor.
2. Failure of field
3. Unbalanced loading and subsequent heating of alternator
4. Overloading
5. Over voltage at Alternator terminals
6. Over speed
7. Ventilation failure
8. Current leakage in the body of the alternator
SIPROTEC 7UM62 Relay
25
26. The SIPROTEC 4 7UM62 is ONE bay, ONE IED (Intelligent Electronic Device)
Siemens is the world market leader in delivering combined protection & control relays.
We provide control functionality with the CFC (Continuous function chart), which is
accepted
as state-of-art in industrial automation.
The numerous other additional functions assist the user in ensuring cost-
effective system management and reliable power supply. Measured values display
current operating conditions. Stored status indications and fault recording provide
assistance in fault diagnosis not only in the event of a disturbance in generator operation.
Combination of the units makes it possible to implement redundancy concepts.
26
27. Advantages:-
Compact design and lower costs:-
Due to integration of many functions into one relay.
Less Maintenance:-
No any rotating parts.
No Drifting(aginf):-
Because of measuring characteristics is fully numerical process.
High measuring accuracy:-
Due to digital filtering and optimized measuring algorithms. Many integrated
add-on functions, for example, for load monitoring, event/fault recording
and the maloperating.
On board Programming:-
Local operation keypad and display designed to modern ergonomic criteria.
Protectin + Monitoring:-
The SIPROTEC 4 7UM62 Protection Relay can do more than just protect.
They also offer numerous additional functions. Be it earth faults, short-circuits,
overloads, overvoltage, overfrequency or under frequencyasynchronous
conditions, protection relays assure continued operation of power stations.
For all size & Types of generators:-
The SIPROTEC 4 7UM62 Protection Relays is a compact unit which has
been specially developed and designed for the protection of small, medium-sized
and large generators.
The integrate all the necessary protections functions and are particularly
suited for the protection of:
Hydro and pumped-storage generators
Co-generation stations
Private power stations using regenerative
energy sources such as wind or
biogases
Diesel generator stations
Gas-turbine power stations
27
28. Industrial power stations
Conventional steam power stations.
The SIPROTEC 4 7UM62 includes all necessary protection functions for large
synchronous and asynchronous motor sand for transformers.
Flexibility:-
The integrated programmable logic functions (continuous function chart
CFC) offer the user high flexibility so that adjustments can easily be made to the
varying power station requirements on the Basis of special system conditions.
Communication:-
The Flexible communication interfaces are open for modern communication
architectures with control system.
Protocol Description
MODBUS RTU Communication & Numerous Automation Solutions
PROFIBUS-DP Internationally standardized communication system
IEC 60870-5-103 Internationally standardized protocol for communication in
the protected area.
IEC 61850 protocol The Ethernet-based IEC 61850 protocol is the worldwide
standard for protection and control system used by power
supply corporations
DNP 3.0 (Distributed Network Protocol version) is a messaging-
based communication protocol
RS 485 BUS Upon failure of a unit, the remaining system continues to
operate without any faults
Fiber-optic double
ring circuit
Fiber-optic double ring circuit is immune to
electromagnetic interference.
Upon failure of a section between two units, the
communication system continues to operate without
disturbance
Remote Operation & Interlocking:-
The Ethernet-based IEC 61850 protocol is the worldwide standard for
protection and control systems used by power supply corporations so information
can also be exchanged directly between bay units.
28
31. Unit connection with neutral earthing transformer :-
Connections to three voltage transformers (phase-to-earth voltages) and in each case
three current transformers, differential protection function connected via generator and unit
transformer; Loading resistor connected either directly to star spoint circuit or via matching
transformers.
Different Relay Opretation of 7UM62 Relay for Alternator Protection:-
1. Definite Time Over current Protection with Under Voltage (I>, ANSI 50/51)
2. Definite Time Over current Protection with Direction Detection(I>>, ANSI 50,51,67)
3. Inverse-Time Over current Protection (ANSI 51V)
4. Thermal Overload Protection (ANSI 49)
5. Unbalanced Load (Negative Sequence) Protection (ANSI 46)
6. Startup Over current Protection (ANSI 51)
7. Differential Protection (ANSI 87G/87M)for Generators and Motors
8. Differential Protection (ANSI 87T) for Transformers
9. Earth Current Differential Protection (ANSI 87GN,TN)
10. Under excitation (Loss-of-Field) Protection (ANSI 40)
11. Reverse Power Protection (ANSI 32R)
12. Forward Active Power Supervision (ANSI 32F)
13. Impedance Protection (ANSI 21)
14. Out-of-Step Protection (ANSI 78)
15. Under voltage Protection (ANSI 27)
16. Overvoltage Protection (ANSI 59)
17. Frequency Protection (ANSI 81)
18. Over excitation (Volt/Hertz) Protection (ANSI 24)
19. Rate-of-Frequency-Change Protection df/dt (ANSI 81R)
20. Jump of Voltage Vector
21. 90-%-Stator Earth Fault Protection (ANSI 59N, 64G, 67G)
22. Sensitive Earth Fault Protection (ANSI 51GN, 64R)
23. 100-%-Stator Earth Fault Protection with 3rd Harmonics (ANSI 27/59TN 3rd Harm.)
24. 100-%-Stator Earth Fault Protection with 20 Hz Voltage Injection (ANSI 64G - 100%)
25. Sensitive Earth Fault Protection B (ANSI 51GN)
26. Inter turn Protection (ANSI 59N (IT))
27. Rotor Earth Fault Protection R, fn (ANSI 64R)
28. Sensitive Rotor Earth Fault Protection with 1 to 3 Hz Square Wave Voltage Injection
(ANSI 4R - 1 to 3 Hz)
29. Motor Starting Time Supervision (ANSI 48)
30. Restart Inhibit for Motors (ANSI 66, 49Rotor)
31. Breaker Failure Protection (ANSI 50BF)
32. Inadvertent Energization (ANSI 50, 27)
33. DC Voltage/Current Protection (ANSI 59NDC/51NDC)
34. Temperature Detection by Thermoboxes
31
32. Different Fault Setting for 10.4MW Steam –Turbine Generator
Protection
Relay
Description Setting Time Circuit Breaker Trip
Turbine
Remark
27 Under
Voltage
Protection
9.5 KV
9.5 KV
Inst.
9 sec
-
-
-
×
- PTR:
11KV/110V
32-1
32-2
Revers
Power
Protection
7 W
13.9W
1 sec.
10sec.
-
× × -
During Normal
Stop
CTR:800/1A
40-1 Loss Of
Excitation
Protection
Zone-1 0.06 sec.
- - -
40-2 Center-
115.67 ohm
Radius
110.38mm
Zone-2 0.50 sec.
× × ×
Center-
69.04 ohm
Radius
63.73 ohm
46-A Negative
Sequence
O/C
Protection
0.06 A 2 sec. - - - CTR 800/1 A
46-T 0.09 A 14 sec. - × -
51 V Voltage
Restrain O/C
Protection
1.6 A TF : 1.7
× × ×
CTR 800/1 A
59 Over Voltage
Protection
124 V TF: 5.7
×
×
×
×
×
×
PTR:
11KV/110V
133 V 0.035
sec.
81 Over
Frequency
Protection
51.5 HZ 0.10 sec. - - -
51.6 HZ 10 sec. - × ×
52.1 HZ 0.10 sec. - × ×
Under
Frequency
Protection
48 HZ 0.10 sec. - - ×
47.5 HZ 10 sec. - × -
47 HZ 1 sec. - × -
87 G Generator
Differential
Protection
0.20 A K1 = 1% × × ×
64R Rotor E/F
Protection
5 Kilo Ohm - - - On Excitation
Panel
58 Diode Failure
Protection
- - - On Excitation
Panel
28G Generator
Over Temp.
(Wdg.)
- - - On Suvimac Panel
- × - On Suvimac Panel
Generator
Over Temp.
(Hot Air)
- - - On Suvimac Panel
- × - On Suvimac Panel
38 BG Gen. Bearing - - -
32
33. Over Temp.
Protection
× × ×
24 A Over
Flux(59.81)
1.08 pu 5 sec. - - -
24 T 1.10 pu 30 sec. × × ×
1.17 pu 2 sec. × × ×
51GN Stator Earth
Fault
Protection
0.10A TF : 1 × × × CTR 800/1 A
Dl-1 GENERATOR OFF LINE
Dl-2 TURBINE NORMAL STOP
Dl-3 BEARING HIGH TEMP. TRIP
Dl-4 GENERATOR STATOR TEMP. HIGH TRIP
Dl-5 OCCELOGRAPH TRIGGER NOT USE
Dl-6 EXERTERNAL VOLTAGE TRANSFORMER FUSE FAILURE
(1) Definite Time Over current Protection with Under Voltage (I>, ANSI
50/51):-
33
34. The over current protection is used as backup protection for the short-circuit
protection
of the protected object. It also provides backup protection for downstream network
faults which may be not promptly disconnected thus endangering the protected
object.
(2) Definite Time Over current Protection with Direction Detection(I>>,
ANSI 50,51,67):-
The over current protection is used as backup protection for the short-circuit
protection of the protected object. It also provides backup protection for downstream
network faults which may be not promptly disconnected thus endangering the
protected object.
(3) Inverse-Time Over current Protection (ANSI 51V):-
The over current time protection represents the short-circuit protection for
small or low voltage machines. For larger machines it is used as back-up protection
for the machine short-circuit protection (differential protection and/or impedance
protection). It provides back-up protection for network faults which may be not
promptly disconnected thus endangering the machine.
(4) Thermal Overload Protection (ANSI 49)
The thermal overload protection prevents thermal overloading of the stator
windings
of the machine being protected.
(5) Unbalanced Load (Negative Sequence) Protection (ANSI 46)
Unbalanced load protection detects unbalanced loads of three-phase induction
motors. Unbalanced loads create a counter-rotating field which acts on the rotor at
double frequency. Eddy currents are induced at the rotor surface leading to local
overheating in rotor end zones and slot wedges. Another effect of unbalanced loads is
overheating of the damper winding. In addition, this protection function may be used
to detect interruptions, faults, and polarity problems with current transformers. It is
also useful in detecting 1-pole and 2-pole faults with magnitudes lower than the load
currents.
34
35. The most common causes are system asymmetries(untransposed lines), unbalanced loads,
unbalanced system faults, and open phases. These system conditions produce negative-
phase-sequence components
of current that induce a double-frequency current in the surface of the rotor, the retaining
rings, the slot wedges, and to a smaller degree, in the field winding.
These rotor currents may cause high and possibly dangerous temperatures in avery short
time., the melting of the wedges in the air gap. ANSI standards have established that the
35
36. limits can be expressed as
2
2i dt k
where
2i
is the negative sequence current flowing. The
machine designer establishes constant k. It can be in the range of 5 – 50. An inverse-time
over current relay excited by negative sequence current can be used for this protection.
(6) Startup Over current Protection (ANSI 51)
(7) Differential Protection (ANSI 87G/87M) for Transformers
Differential protection systems operate according to the principle of current
comparison
and are therefore also known as current balance protection systems. They utilize the
fact that in a healthy protected object the current leaving the object is the same as
that which entered it (current Ip, dotted in the following figure).
(8) Differential Protection (ANSI 87M/G) for Generators and Motors
Differential protection systems operate according to the principle of current
comparison and are therefore also known as current balance protection systems.
They utilize the fact that in a healthy protected object the current leaving the object is
the same as that which entered it.
This result shows that for the internal fault under ideal conditions Idiff = Istab.
Consequently, the characteristic of internal faults is a straight line with a upward
slope of 45° (dot-and-dash line in the following figure).
36
37. (9) Earth Current Differential Protection (ANSI 87GN,TN)
The earth current differential protection detects earth faults in generators and
transformers
with a low-ohmic or solid star point earthing. It is selective, and more sensitive than
the classical Differential protection
(10) Under excitation (Loss-of-Field) Protection (ANSI 40)
If The field excitation is lost while the mechanical input remains intact. Since the
generator is already synchronized with the grid, it would attempt to remain synchronized by
running as an iduction generator. As an induction generator, the machine speeds up slightly
above the synchronous speed and draws its excitation from the grid.
On loss of excitation, the terminal voltage begins to decrease and the current
begins to increase, resulting in a decrease of impedance and also a change of power factor.
37
38. (11) Reverse Power Protection (ANSI 32R)
Reverse power protection is used to protect a turbo-generator unit on failure of
energy to the prime mover when the synchronous generator runs as a motor and
drives the turbine taking motoring energy from the network. This condition leads to
overheating of the turbine blades and must be interrupted within a short time by
tripping the network circuit-breaker. For the generator, there is the additional risk
that, in case of a malfunctioning residual steam pass (defective stop valves) after the
switching off of the circuit breakers, the turbine-generator-unit is speeded up, thus
reaching an over speed. For this reason, the system isolation should only be
performed after the detection of active power input into the machine.
(12) Forward Active Power Supervision (ANSI 32F)
The machine protection 7UM62 includes an active power supervision which
monitors whether the active power falls below one set value as well as whether a
38
39. separate second set value is exceeded. Each of these functions can initiate different
control functions.
(13) Impedance Protection(distance protection) (ANSI 21)
The distance relay applied for this function is intended to isolate the
generator from the power system for a fault which is not cleared by the transmission
line breakers.
Machine impedance protection is used as a selective time graded protection to
provide shortest possible tripping times for short-circuits in the synchronous
machine, on the terminal leads as well as in the unit transformer. It thus also
provides backup protection functions to the main protection of a power plant or
protection equipment connected in series like generator, transformer differential and
system protection devices.
(14) Out-of-Step Protection (ANSI 78)
Depending on power network conditions and feeding generators, dynamic
occurrences such as load jumps, short-circuits not disconnected quickly enough,
auto-reclosure or switching actions, may cause system swings. Such power swings
endanger power network stability. Stability problems often result from active power
swings which can lead to pole-slipping and generator overloading.
The point at which the apparent impedance swing crosses the impedance line
between the generator and the system is referred to as the electrical center of the
swing and represents the point at which zero voltage occurs when the generator and
the system are 180 degrees out-of-phase. During pole slipping the voltage magnitude
between the generator and the system reaches two per unit when the angle difference
reaches 180 degrees, which can result in high currents that cause mechanical forces
in the generator stator windings and undesired transient shaft torques. It is possible
for the resulting torques to be of sufficient magnitude to cause the shaft to snap or
damage turbine blades.
(15) Under voltage Protection (ANSI 27)
39
40. Under voltage protection detects voltage dips in electrical machines and
avoids inadmissible operating states and possible loss of stability. Two-pole short
circuits or earth faults cause asymmetrical voltage collapse. Compared with three
single phase measuring systems, the detection of the positive phase-sequence system
is not influenced by these procedures and is particularly advantageous for assessing
stability problems.
(16) Overvoltage Protection (ANSI 59)
Overvoltage protection serves to protect the electrical machine and connected
electrical plant components from the effects of inadmissible voltage increases. Over
voltages can be caused by incorrect manual operation of the excitation system, faulty
operation of the automatic voltage regulator, (full) load shedding of a generator,
separation of the generator from the system or during island operation.
(17) Frequency Protection (ANSI 81)
The frequency protection function detects abnormally high and low
frequencies of the generator. If the frequency lies outside the admissible range,
appropriate actions are initiated, such as separating the generator from the system.
A decrease in system frequency occurs when the system experiences an increase in
real power demand, or when a frequency or speed control malfunction occurs. The
frequency decrease protection is also used for generators which (for a certain time)
function on an island network. This is due to the fact that the reverse power
protection cannot operate on drive power failure. The generator can be disconnected
from the power system using the frequency decrease protection.
An increase in system frequency occurs e.g. when large loads (island network) are
removed from the system, or on frequency control malfunction. This entails risk of
self excitation for generators feeding long lines under no-load conditions.Through the
use of filters measurement is practically independent of harmonic influencesand very
accurate.
(18) Over excitation (Volt/Hertz) Protection (ANSI 24)
Over excitation protection is used to detect inadmissibly high induction in
generators and transformers, especially in power station unit transformers. The
protection must intervene when the limit value for the protected object (e.g. unit
transformer) is exceeded. The transformer is endangered, for example, if the power
station block is disconnected from the system from full-load, and if the voltage
regulator either does not operate or does not operate sufficiently fast to control the
associated voltage rise. Similarly a decrease in frequency (speed), e.g. in island
systems, can lead to an inadmissible increase in induction.
An increase in induction above the rated value very quickly saturates the iron
core and causes large eddy current losses.
40
41. (19) Inverse-Time Under voltage Protection (ANSI 27)
The inverse under voltage protection mainly protects consumers (induction
machines) from the consequences of dangerous voltage drops in island networks
avoiding inadmissible operating conditions and possible loss of stability. It can also be
used as a criterion for load shedding in interconnected networks. Two-pole short
circuits or earth faults cause asymmetrical voltage collapse. Compared with single
phase measuring systems, the detection of the positive phase-sequence system is not
influenced by these procedures and is therefore especially useful for assessing
stability problems.
(20) Rate-of-Frequency-Change Protection df/dt (ANSI 81R)
With the rate-of-frequency-change protection, frequency changes can be
quickly detected.
This allows a prompt response to frequency dips or frequency rises. A trip command
can be issued even before the pickup threshold of the frequency protection (see
Section 2.23) is reached.
Frequency changes occur for instance when there is an imbalance between the
generated and the required active power. They call for control measures on one hand
and for switching actions on the other hand. These can be unburdening measures,
such as network decoupling, or disconnection of loads (load shedding). The sooner
these measures are taken after a malfunction appears, the more effective they are.
The two main applications for this protection function are thus network
decoupling and load shedding.
(21) 90-%-Stator Earth Fault Protection (ANSI 59N, 64G, 67G)
The stator earth fault protection detects earth faults in the stator windings of
three phase machines. The machine can be operated in busbar connection (directly
connected to the network) or in unit connection (via unit transformer). The criterion
for the occurrence of an earth fault is mainly the emergence of a displacement
voltage, or additionally with busbar connection, of an earth current. This principle
makes possible a protected zone of 90 % to 95 % of the stator winding.
(22) Sensitive Earth Fault Protection (ANSI 51GN, 64R)
The highly sensitive earth fault protection detects earth faults in systems with
isolated or high-impedance earthed star point. This stage operates with the
magnitude of the earth current. It is intended for use where the earth current
amplitude gives an indication of the earth fault. As an example of this is with
electrical machines in busbar connection in an isolated power system, where during a
machine earth fault of the stator winding, the entire network capacity supplies the
earth fault current, but with a network earth fault, the earth fault current is negligible
due to the low machine capacitance.
The current may be measured using toroidal CTs.
41
42. (23) 100-%-Stator Earth Fault Protection with 3rd Harmonics (ANSI 27/59TN
3rd Harm.)
(24) 100-%-Stator Earth Fault Protection with 20 Hz Voltage Injection (ANSI
64G - 100%)
(25) Sensitive Earth Fault Protection B (ANSI 51GN)
The IEE-B sensitive earth current protection feature of 7UM62 provides
greater flexibility and can be used for the following applications.
Applications
• Earth current monitoring to detect earth faults (generator stator, terminal
lead,ttransformer).
• 3rd harmonics earth current measurement for detection of earth faults near the
generator
star point. The connection is accomplished in the secondary circuit of the neutral
transformer.
• Protection against load resistances by means of single-phase current monitoring.
• Shaft current protection in order to detect shaft currents of the generator shaft and
prevent that bearings take damage. The function is mainly used for hydro-electric
generators.
(26) Inter turn Protection (ANSI 59N (IT))
The inter turn fault protection detects faults between turns within a generator
winding (phase). This situation may involve relatively high circulating currents that
flow in the short-circuited turns and damage the winding and the stator. The
potective function is characterized by a high sensitivity.
42
43. Given the way the generators are constructed, it is rather unlikely that an inter
turn fault will occur.
Generators with a separate stator winding (e.g. large-sized hydro-electric
generators) are more likely to be affected. In this configuration, the transverse
differential protection or the zero sequence current protection are used instead
between the connected star points.
(27) Rotor Earth Fault Protection R, fn (ANSI 64R)
Rotor earth fault protection is used to detect earth faults in the excitation
circuit of synchronous machines. An earth fault in the rotor winding does not cause
immediate damage; however, if a second earth fault occurs it constitutes a winding
short-circuit of the excitation circuit. The resulting magnetic imbalances can cause
extreme mechanical forces which may destroy the machine.
(28) Sensitive Rotor Earth Fault Protection with 1 to 3 Hz Square Wave
Voltage Injection (ANSI 4R - 1 to 3 Hz)
(29) Motor Starting Time Supervision (ANSI 48)
(30) Restart Inhibit for Motors (ANSI 66, 49Rotor)
(31) Breaker Failure Protection (ANSI 50BF)
In the event of scheduled downtimes or a fault in the generator, the generator
can remain on line if the circuit-breaker is defectiveand could suffer substantial
damage.
Breaker failure protection evaluates a minimum current and the circuit-
breaker auxiliary contact. It can be started by internal protective tripping or
externally via binary input. Two-channel activation avoids overfunction.
(32) Inadvertent Energization (ANSI 50, 27)
The inadvertent energizing protection serves to limit damage by accidental
connection of the stationary or already started, but not yet synchronized generator,
by fast actuation of the mains breaker. A connection to a stationary machine is
equivalent to connection to a low-ohmic resistor. Due to the nominal voltage
impressed by the power system, the generator starts up with a high slip as an
43
44. asynchronous machine. In this context, unpermissibly high currents are induced
inside the rotor which may finally destroy it.
(33) DC Voltage/Current Protection (ANSI 59NDC/51NDC)
(34) Temperature Detection by Thermoboxes
Up to 2 RTD boxes with a total of 12 measuring points can be used for
temperature detection and evaluated by the protection device. They are particularly
useful for monitoring the thermal condition of motors, generators and transformers.
Rotating machines are additionally monitored for transgression of bearing
temperature thresholds.
The temperatures are measured in different locations of the protected object
by employing temperature sensors (RTD = Resistance Temperature Detector) and are
transmitted to the device via one or two 7XV566 RTD-boxes.
Differential relaying will detect threephasefaults, phase-to-phase faults, double-phase-to-
ground faults, and somesingle-phase-to-ground faults, depending upon how the generator is
grounded.
Differential relaying will not detect turn-to-turn faults in the same phase sincethere is no
difference in the current entering and leaving the phase winding.
Where applicable, separate turn fault protection may be provided with the splitphaserelaying
scheme.
This scheme will be discussed subsequently. Differentialrelaying will not detect stator ground
faults on high-impedance groundedgenerators.
The high impedance normally limits the fault current to levelsconsiderably below the practical
sensitivity of the differential relaying.
Threetypes of high-speed differential relays are used for stator phase fault detection:percentage
differential, high-impedance differential, and self-balancingdifferential.
Percentage Differential Protection
44
45. Automatic Field Suppression and use of Neutral Circuit Breaker
In the event of a fault on a generator winding even though the generator circuit breaker is tripped, the fault
continues to be fed as long as the excitation will exist because emf is induced in the generator itself.
So it is necessary to discharge excitation magnetic field in the shortest possible interval of time. Hence, it is
to be ensured that all the protection system not only trip the alternator circuit breaker but also trip
automatic field discharge switch.
The Schematic Diagram for Automatic Field Suppressing and opening of the neutral Circuit Breaker
45
46. In the event of fault the circulating relay contact is closed and so trip coils TC1, TC2, TC3 and TC4 are
energized.
The trip coil TC1 opens the main Circuit Breaker while TC2 and TC4 opens the upper contacts, shorts the
lower contacts so as to short-circuit the field winding through resistor R1 and R2.
This Process of discharging consists of the isolation of the exciter from the alternator rotor field winding
and involves the dissipation of magnetic energy stored in the inductive reactance of the rotor and the main
exciter windings.
After the Study of all Protection of 7UM62 Relay we have faced a problem that how we can test that
the parameters calculated are correct or not or whether there is any defect that crept in the relay.
Problem associated in 7UM62 Relay:-
I. Burn out of Microprocessor:-
Burn Out is rare case in the 7UM62 Relay. It can happened by ambient
temperature rise in surrounding.
II. Mal operation:-
i. Wrong Connection:-
Mal operation occurs due to wrong Connections of Wires with
Relay to C.T. & P.T.
ii. Imperfect Time & Peak up Setting:-
Mal operation occurs due to Imperfect time & Peak up setting so
relay operate when it’s not required.
III. During testing of one protection function an interfering signal from another function
will come and corrupt the test results.
46
47. Solution:-
i. Provide Cooling System:-
To cool down its surrounding temperature we have to installed in Air
Conditioner Room.
ii. During testing of one protection function an interfering
signal from another function will come and corrupt the
test results.
In this case the interfering functions needs to be blocked. i.e. If you
conduct Differential Protection on Generator we have to Blocked Earth Fault
Differential Protection out of step, Inverse time over current because Earth
fault Differential Current Protection, out of step, Inverse time over current will
operate fast than Differential Current Transformer.
47
48. iii. Mal Operation of Relay:-
Mal Operation can be Detected by Testing & Simulation of Relay by
testing kit.
Omicron CMC 356
The Universal Relay Test Set and Commissioning Tool
Omicron CMC 356 can Detect the Wrong Connection or wrong Time or
Wrong Pick up setting in 7UM62 Relay by Simulating ( Creating artificial Faults
in Sytem).
48
49. The CMC 356 is the universal solution for testing all generations and types of protection
relays.
Its powerful six current sources (three-phase mode: up to 64 A / 860 VA per channel) with a
great dynamic range, make the unit capable of testing even high-burden electromechanical
relays with very high power demands. Commissioning engineers will particularly appreciate
the possibility to perform wiring and plausibility checks of current transformers, by using
primary injection of high currents from the test set. The CMC 356 is the fi rst choice for
applications requiring the highest versatility, amplitude and power.
Application of CMC 365:-
Protection Relay Test Set
Power System Simulator
Programmable Voltage and
Current Source
Universal Tool for Substation
49
50. Commissioning
The Siemens 7UM62x test template includes the pick-up and trip time value tests which are
performed in a standardized way. For the pick-up value testing, the setting value is evaluated
by a ramp increasing the variable under test until the pick-up value is reached.
Trip times are tested by simulating a fault which exceeds the pick-up value and the specific
tolerances.
This results in a trip command of the tested protection function. The time between the
simulation of the fault and the reception of the trip signal is measured and evaluated.
50
