Bueno Electric BEPR- 554U User manual

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BEPR- 554U
Generator Protection Device
Technical Manual
Operation Manual

Part 1
Technical Manual

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1 Introduction to Device
BEPR- 554U generator protection device is designed specifically for small and medium sized
generators, including generator differential protection and generator backup protection
Function BEPR-554
Differential protection √
Overvoltage protection √
Loss of excitation protection √
Compre ensive 3Uo stator ground protection √
Frequency protection √
One-point ground protection √
Rotator two-point ground protection √
Generator stator ground protection √
Reverse power protection √
Non-electric signal protection √
TA & TV breakage protection √
The device has the following features:
Main processor of the device is Motorola’s 32-bit microprocessor with fast speed, high reliability, rich
resources and big room to expandability;
The whole panel is a 240 × 128 big screen LCD which is operated and displayed in Chinese and has
friendly human-machine interface;
Multiple kinds of communication interfaces Reserved RS-232, RS-485/422, CAN and Ethernet can
conveniently conduct high-speed communication with the local station or remote system;
A/D has high conversion accuracy and fast speed and the device does not need adjustable parts to
automatically adjust sampling accuracy;
The device has well-improved software and hardware watchdog self-test function and automatically
blocks the trip in case of failure of CPU;
The device uses back inserted structure to separate light current from heavy current so as to greatly
enhance anti-jamming property of the device;

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The device has overall, rich and simple debug functions

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2 ardware Configuration of the Device
With an aim to executing the above functions in a set of hardware system and taking flexibility and
adaptability of the device into consideration, modular design is conducted for the device The device is
composed of the following modules:
2.1 AC and DC input module (AC/DC)
Three kinds of converting circuits are set according to different types of input signals
AC voltage: set isolation conversion of intermediate transformer, such as extreme voltage of generator
and high-tension side voltage of main transformer etc
AC current: set isolation conversion of intermediat converter and obtain voltage at secondary side
parallel resistance 1A and 5A converters are selected and secondary resistance is changed to meet the
requirement of measurement ranges of different currents, such as extreme current of generator and neutral
point current etc
DC voltage and current: set advanced isolated conversion of hall sensor, such as rotator voltage of
generator and diverter voltage of rotator
2.2 ost processing module (CPU)
All analogs resulting from conversion by AC and DC input modules can effectively filter out signals
within pass band through active filter with lowpass filtering and bandpass filtering to meet filtering
requirements of different frequency signals and achieve less than 1% of attenuation of fundamental wave,
and concurrently attenuation ratio and phase shift of analogs of all channels can reach good consistency
Figure 2-1: ardware of NSC 554 generator protection device
POWER
POWERPOWER
POWER
AC
ACAC
AC CPU
CPUCPU
CPU
MMI
Conversion
module of
AC and DC
input (TA
and TV etc )
A/D
CPU
Processor
CAN communication
Output
and
signal
Power
Voltage input
Current input
Human-
machine
dialogue
TRIP
TRIPTRIP
TRIP
DC input

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Central processing unit (CPU) is composed of A/D conversion, state quantity input, state quantity
output (used for pulse output of trip and close, alarm signal output, opening of block relay and other signal
outputs), microprocessor CPU, RAM, ROM, FLASH RAM and EEPROM High performance
microprocessor CPU (32-bit), large capacity ROM (256K bytes), RAM(256K bytes) and FLASH RAM (1M
bytes) enable the CPU module to have strong data processing and recording capacity and achieve various
complex fault handling schemes and record a lot of fault data C language programming can enable the
program to have strong reliability, portability and maintainability
All parts relevant to CPU are concentrated in a plug-in unit and all input and output state quantities go
through photoelectric coupling isolation If the parts in this module are in abnormal conditions, then main
processor drives block relay and cuts off OPS at photoelectric coupling output side of state quantity output
Auxiliary processor drives the above block relay when main processor is in abnormal conditions Block
relay will not be reset unless it is powered down Mutual monitoring of dual processors ensures operation
reliability of the device
The terminals of CPU module are used to connect in strap, dedicated input signal, output signal and
position signal required by the CPU
Analog/data conversion (A/D) uses 14-bit high accuracy, high stability, high speed and multi-channel
concurrent conversion unit whose precision working current can reach 0 04In and precision working voltage
can reach 0 2V to enhance measuring accuracy and speed All analogs can effectively filter out, through
lowpass filtering, higher harmonic wave and achieve less than 1% of attenuation of fundamental wave and
attenuation ratio and phase shift of analogs of all channels can reach good consistency
Figure 2-2 Schematic diagram of CPU module
Output
Signal and alarm output
To terminal
CPU
CAN
RAM
ROM
FLASH
I/O
To MMI
Terminal signal
Motherboard signal
EEPROM
Analog
i
nput
A/D conversion
CPU

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2.3 uman-machine module (MMI) module
Human-machine module (MMI) is installed in the rear of the whole panel of the device The module
includes microprocessor (32-bit), large capacity ROM (512K bytes), RAM (1M bytes), FLASH RAM (1M
bytes), EEPROM, input and output state quantity, communication control unit, clock, LCD with big screen
(240 × 128), full screen operating keyboard and signal indicating lamp etc
The module is mainly used for human-machine interface management Its main functions include
keyboard operation, management of liquid crystal display, printing, signal lamp indication, communication
with debug computer, monitoring system of transformer substation or remote safety automated device, GPS
time calibration (minute/second pulse time) and information information with main CPU
The communication with all CPUs uses CAN and the communication rate is 100Kbps, which breaks
through the bottleneck of internal communication of the device and enhances internal information
transmission rate of the device
External communication has three ports, with one being set on the panel and two being set on the back
panel of communication interface module (COM panel) RS232 serial port on the panel is used to be
connected with PC Two communication ports on the back panel of communication interface module can be
set as different physical interfaces as required
485 interface, Ethernet interface and optical fiber interface etc are set up on the back panel to meet
the needs of different automatic system when the device connects in the plant and station automatic systems
The port on the back panel can be set as RS232 interface (used to drive serial printer) or RS422/485
interface (it is used to communication with engineer station or for centralized printing)
Communication specification adopts IEC60870-5-103 specification
Electronic schematic of Human-machine module (MMI) is shown in Figure 2-3:
CPU
Serial interface
RAM
ROM
FLASH
I/O
To CPU module
Communication port
To CPU and control etc
Signal and alarm output
LCD
Keyboard
EEPROM Panel signal
CAN
Ethernet Communication port

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2.4 Output and signal module (TRIP)
This module interfaces with the commands sent by CPU module and provides device
actions and alarm signals which can be transmitted to either signal lamp on the panel or central
signal device Each unit is equipped with a set of three-phase operation circuit Device can
adaptive tripping current, without on-site adjustment
Figure 2-3 Electronic schematic of MMI module

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3 Technical indicators
3.1 Operating environment
Working temperature:-20 ℃～ 60 ℃ , average temperature within 24 hours does not exceed 35 ℃
Storage temperature:-25 ℃～ 80 ℃ , not apply excitation at limiting value; irreversible changes will not
occur in the device The device should normally work after temperature is recovered
Relative humidity: not more than 95% (without dew)
Atmospheric pressure: 80 ～ 110kPa (below relative sea-level elevation of 2KM)
3.2 Nominal parameters
Rated DC voltage: 220V/110V (indicated in the order), around 10W, fluctuation range: -20% ～
+10%
Rated AC data:
Phase voltage: 3/100 V
Line voltage: 100V
AC: 5A/1A (indicated in the order)
Rate frequency: 50Hz
3.3 Technical parameters of device
Input circuit: 24V D C 2 4mA at each point
Output contact rating: 30W( τ =5ms), 220V D C or 0 5A D C
Trip time: ＜ 20ms
Each phase of AC voltage circuit of the device at nominal parameter ≤ 0 2VA
Each phase of AC current circuit of the device at nominal parameter ≤ 0 3VA
Voltage, current and power: 0 5 grade
Phase angle measurement error ≤ 1 °
Impedance measurement error ≤ 5%

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4. Insulating Property
4.1 Insulation resistance
Megohmmeter with open circuit voltage 500V is used to measure insulation resistance of live part and
dead part of the device and casings of the device and electrically unassociated circuits of the device and the
insulation resistances of all circuits with different grades are not less than 100M Ω in atmospheric
conditions of normal test
4.2 Dielectric strength
The device can withstand line frequency pressure test with 50Hz frequency and 2000V voltage and
duration of 1 minute without breakdown and flashover and destroyed components in atmospheric conditions
of normal test The electric potentials of the remaining circuits are interconnected and grounded when
voltage is applied on any circuit during test
4.3 Impulse voltage
Short-time impulse voltage test with 1 2/50µs standard lightning wave is applicable for grounding of
power input circuit, AC input circuit and output contact circuit of the device and between circuits in
atmospheric conditions of normal test and voltage of open circuit test is 5kV
4.4 umid-heat resistance property
The device can withstand humid heat test stated in Chapter 21 of GB7261 The highest test
temperature is +40 ℃ and maximum humidity is 95% and test duration is 48 hours and each cycle lasts
24-hour alternating humid heat test Insulation resistances of all conducting channels to exposed dead metal
part, insulation resistance between casings and between all electrically unassociated circuits should be
measured to be not less than 1 5M Ω and medium VOLTAGE WITHSTAND STRENGTH should be
measured to be not lower than 75% of voltage amplitud in dielectric strength test voltage amplitude stated in
2 3 2 according to 2 3 1 within two hours before the test is finished
4.5 Electromagnetic interference resistance property
4 5 1 Impulsive interference
The device can withstand interference test stated in GB6162 and test power frequencies are 100kHz
and 1MHz and test voltage is attenuating oscillatory wave of common mode 2500V and differential mode
1000V Power is applied on the tested device in advance and interference test voltages are added according
to critical conditions listed in No 3 3 of GB6162 and the device will not have maloperation and reject
operation
4 5 2 Fast transient disturbance

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The device can withstand fast transient interference test with IV level (4kV ± 10%) stated in IEC255
－ 22 － 4 standard
4 5 3 Electrostatic discharge
The device can withstand electrostatic discharge test with IV level (space discharge 15kV and contact
discharge 8kV) stated in IEC255 － 22 － 2 standard
4.6 Mechanical property
4 6 1 Vibration
The device can withstand vibration and endurance test with rigorous ranking level I stated in 16 3 of
GB7261
4 6 2 Impact
The device can withstand vibration and endurance test with rigorous ranking level I stated in 17 5 of
GB7261
4 6 3 Collision
The device can withstand vibration and endurance test with rigorous ranking level I stated in 18 of
GB7261

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5 Protection Configuration
Multiple protection functions and non-electric signal interface can be provided according to
requirements on protection of generator transformer in Technical Regulations on Relay Protection and
Safety Automatic Device to meet the requirement on protection of generator transformer unit of small sized
generating unit The protection requirement on generator, main transformer, station transformer, high
voltage reserved transformer, excitation transformer and large synchronous phase modifier can be met
Protection configuration is flexible and reasonably designed to meet counter measures requirement of power
system and ensure operational reliability of the device
5.1 Differential protection of generator
5 1 1 Protection Principle
The differential action of the generator can use single-phase differential action mode Single-phase
differential action mode: any phase differential protection action, namely tripping This mode is equipped
with TA line broken detection function Differential protection is transiently blocked in case of TA line
broken and the signal of TA line broken is delayed When protection braking current is more than knee
current, locking of TA line broken is released, namely, setting TA line broken and not blocking differential
action
The protection is equipped with threshold crossing alarm function of differential current Differential
protection can be braked through secondary harmonic wave (indicated in the order)
Percentage restraint is improved in digital protection compared to traditional protection principle It is
composed of no restraint part and percentage restraint part and has higher sensitivity and capacity of
anti-TA saturation
Its action equation is as follows:





≥+
+−−≥+
qTN
qgTNSTN
III
IIIIKII
&&
&&&& )2/(
Of which: I
g
: - knee-point current of curve
I
q
: -starting current of curve
K
s
: - slope of curve

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Iq
Isd
Ig
Iz
Id
qgTNSTN
IIIIKII +−−≥+ )2/( &&&&
Figure 5-1 Characteristic curve of percentage restraint
Criterion for CT line broken :
Condition 1: abrupt change starts;
Condition 2: abrupt change must be negative abrupt change;
Condition 3: No abrupt change on the opposite side of abrupt change;
Condition 4: No change on other sides
5 1 2 Input analog
Current at generator end: I
AT
, I
BT
, I
CT
;
Neutral point current of generator: I
AN
, I
BN
, I
CN
;
Protection calculation uses differential current method
5 1 3 Logic chart of protection is as follows:
A phase differential
B phase differential
C phase differential
or
&
TA line broken alarm
Action tripping
Differential current
threshold crossing t/0 Differential current
threshold
TA wire broken

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Figure 5-2 Differential output logic of generator: single-phase differential action mode
5 1 4 Setting contents and setting principles
1) Setting contents
Setting contents
No
Setting name Unit
Setting range and
instructions
1
Quick-break setting A
See setting
principels and
setting proposals
2
Differential setting
A
3
Proportional differential inflection
point setting
A
4
Differential braking proportion
coefficient
5
Remove break line blocking Uf2
V
6
Differential current out limited setting
A
7
Differential current out limited delay
setting
S
Control characters
No Setting 1 Setting 0
1
Quick-break protection input Quick-break protection quit
2
CT break line check input CT break line check quit
3 CT break line not bloking differential CT break line bloking differential
2) Setting principels and setting proposals
(a) Proportional coefficient of the brake Kz (rate of curve)
Kz should accord escape outside three-phase short circuit when the maximum transient unbalanced
differential current to setting, usually, the generator differential use Kz = 0 3 ~ 0 5, unit: no
(b) Starting current Iq
Pickup current of setting differential protection: Iq=0 3 ～ 0 4Ie, unit:A;
According to avoid the maximum unbalanced differential current under the condition of normal
setting Unbalanced differential current reasons: mainly is the variable ratio error of differential protection
on both sides of the TA and the adjustment error of channel circuit protection device
(c) Knee-piont current Ig
Knee-point current of setting differential protection: Ig=0 5 ～ 0 8Ie, unit:A;

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The size of the Ig, decided to start braking effect to protect the current size, avoid external fault is
recommended after resection of the transient process of the maximum unbalanced differential current
setting
(d) Differential instantaneous Is
Differential instantaneous Isd Isd: Is=4 ～ 8Ie, unit: A
Differential action occurs when differential current of generator is more than the setting ID despite the
breaking
It is based on rated current of the generator
(e) Generator rated current Ie
Calculate based on
ϕ cos3
T
Uen
Pe
Ie =
Inside: Pe Generator power rating , K;
Ue Generator voltage rating, KV;
T
n
ratio of differential TA;
ϕ cos
The rated power factor of generator
(f) Differential protection sensitivity calibration
According to relevant technical regulations, longitudinal differential protection, the sensitivity of
generator must meet the machine end two-phase metallicity short-circuit, the sensitive coefficient of the
differential protection Ksen2, Ksen sensitive coefficient is defined as a machine side two-phase metallicity
short-circuit, when the short circuit current and the ratio of the differential protection operating current, the
bigger the Ksen, protective action is sensitive, the higher reliability
Digital protection sensitivity calibration required by regulations, because only Ksen meet the
requirements, to ensure that when the internal fault, there is all kinds of aperiodic component in fault current,
TA saturation effects, TA transient characteristics influence and so on, reliable protection action
Ksen 、 Kz and differential protection setting values, Iq, Ig have relations, especially the Kz affected
most General advice according to this specification values, Ksen can meet the requirements
5.1.5 The engineering application considerations
TA secondary circuit open circuit would cause the danger of high voltage, especially large
generating units For this purpose, the recommended TA break line not locking differential
protection scheme

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5.2 Generator stator ground protection
5.2.1 The protection reflects zero sequence voltage size of generator
Fundamental wave type stator ground fault protection, protection for machine side to about
90% within the scope of the stator winding earth fault As a small stator earthing protection of
the unit Also can use with the three times harmonic stator ground protection to protect fault
protection of 100% of the large and medium-sized generator stator ground fault
5 2 1 2 3U0 Protection principle
The protection reflects zero sequence voltage size of generator The protection has third harmonic
wave filtering function Zero sequence voltage is obtained from opening △ winding of generator terminal
TV or neutral point TV secondary side (also from secondary square winding of arc suppressing coil)
Action equation 3Uo>3Uog ， 3Uo is opening △ winding of generator terminal TV or neutral point TV
secondary side (also from secondary square winding of arc suppressing coil); 3Uog is action voltage fixed
value
5.2.1.3 Logic chart of protection is as follows: 
When the zero sequence voltage as the input voltage of stator ground fault protection from opening
△ winding of generator terminal TV, in order to ensure when the TV break line protection misoperation,
needs to introduce a TV break line locking
3U0> t/0
发信或跳闸
Figure 5-3 Tripping logic of 3Uo generator stator ground protection
5 2 1 4 Setting contents and setting principles
1) Setting contents
Setting contents
No Setting name Unit Setting range and
instructions
1 Stator ground 3Uo setting V See setting
principels and
setting proposals
2 Stator ground 3Uo delay S
Control characters
No Setting 1 Setting 0
1 TV break line lockIng 3Uo TV break line not lockIng 3Uo
2) Setting principles and setting proposals
(a) Action voltage 3Uog
signaling or tripping

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In protection device, set up the good performance of the three times harmonic filtration device,
therefore, 3 uog should based on escape during normal running opening △ winding of generator terminal
TV or neutral point TV secondary side may be the biggest wave of zero sequence voltage to setting
When the stator lead wire is not enclosed bus bar, and pass the wear casing wall from outdoor,could be
10 ～ 13V
When the stator lead wire is not enclosed bus bar, could be 5 ～ 10V
(b) Action delay
Deferred operation time of setting protection, unit (s) t=6s ～ 9s
5 2 2 The protection reflects zero sequence current size of generator
Zero sequence current of the stator ground fault protection, suitable for the machine end position
three-phase outlet with zero sequence current transformer of small generators The protection can be
separately as a generator of the internal stator winding the stator ground fault protection
5 2 2 1 3I0 Protection principle 
Protect access 3 IO current, from the zero sequence current transformer secondary qualification , in the
generator terminal three-phase outlet
Action equation 3Io>3Iog, 3Io On machine side three-phase line zero sequence current transformer of
the secondary current; 3Iog is action current fixed value
5 2 2 2 Logic chart of protection is as follows:
Figure 5-4 Tripping logic of 3Io generator stator ground protection
5.2.2.3 Setting contents and setting principles
1) Setting contents
Setting contents
No Setting name Unit Setting range and
instructions
1 Stator ground 3Io setting A See setting
principels and
setting proposals
2 Stator ground 3Io delay S
Control characters
3I0> t/0
signaling or tripping

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No Setting 1 Setting 0
1 3I0 stator ground input 3I0 stator ground quit
2) Setting principles and setting proposals
Of zero sequence current action value 3 I0g setting, quite tedious The main reason is that zero
sequence TA no strain ratio, a zero sequence current is by magnetic flux leakage to the secondary of TA
For this purpose, the setting value should be issued by the generator primary side zero sequence
current Its value should refer to the security of the generator allows determining grounding current, such as
4 A or 3 A
When the primary current action is determined, with a long wire through the zero sequence TA to check
the single phase current When is equal to a setting into the current when the current action, observation of the
ma number as shown on the interface, the ma number as fixed values input device and curing
Deferred operation time of setting protection, unit (s) t=6s ～ 9s
5.3 Overvoltage protection of generator
5 3 1 Protection principle 
The protection reflects voltage size of generator terminal
Voltage is obtained from line voltages of generator terminal TV and three line voltages are and/or
relation, such as U
CA
voltage
Tripping mode: signaling or tripping 
U
CA
> t/0
发信或跳闸
Figure 5-4 Overvoltage protection tripping logic of generator
5 3 2 Setting contents and setting principles 
1) Setting contents
Setting contents
No Setting name Unit Setting range and
instructions
1 Overvoltage setting V See setting
principels and
setting proposals
2 Overvoltage delay setting S
Signaling or tripping

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2) Setting principles and setting proposals
Overvoltage protection voltage, shall, depending on the type of generator and excitation mode, allow
the overvoltage of the ability and the condition of stator winding insulation to decide
(a) Overvoltage setting
 For the steam turbine generator
Ug＝（1.3～1.35）Ue
 For the hydro-generator
Ug＝1.5Ue
 For the hydro-generator with silicon controlled excitation
Ug＝（1.3～1.4）Ue
(b) Action delay t may be（0.3～0.5）S
5.4 Static stability excitation loss protection of generator
5 4 1 Protection principle
Loss of excitation protection is composed of measurement impedance criterion of generator terminal,
low voltage criterion of rotator, low voltage criterion of transformer high tension side and stator overcurrent
criterion The setting boundary of impedance is generally boundary circle or other shapes of static stability
If impedance circle set according to static stability boundary cannot meet the requirement in case of
under-excitation operation of generator, one of the following measures are generally taken to skive off
under-excitation operation zone
1: Move downward and set impedance circle according to stepout boundary
2: Use two straight lines through origin point to skive off under-excitation operation zone The depth
of under-excitation can be set
3: Use under-excitation operation zone (circular characteristics) to skive off leading phase zone
Operational equation of rotator low voltage:
Vfl zdVfd <
; Vfd<Vfl zd (1)
)( PtPKzdVfd −< ; Vfd>Vfl zd (2)
Of which:
Sn
× =Kk
Vfde
zdKfd
Vfd: rotator voltage

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Vfl zd: operating value of rotator low voltage
Vfde: rotator voltage (V) of generator in case of full load
Sn: rated power (MVA) of generator
Kk: reliable coefficient
Kfd zd: scale coefficient of rotator low voltage
P: generator output
Pt: Reactive power of generator
Take static stability boundary criterion for example to describe the composition of loss of excitation
protection principle:
Loss of excitation signal is sent and excitation switch command is output when rotator low voltage
criterion is met The criterion can predict whether generator loses stability due to loss of excitation so as to
take timely measures (switch excitation etc ) before generator loses stability to prevent the accident from
deteriorating
High-tension side voltage of the system with insufficient reactive power reserve will probably reach
system voltage breakdow before generator loses static stability after generator loss of excitation Therefore,
it indicates that loss of excitation of generator has threatened safe operation of power system when rotator
low voltage criterion and high tension side low voltage criterion are met and generator is tripped after
tripping command is sent by “and gate” logic
Destabilization signal is sent through “and gate” circuit when rotator low voltage criterion and static
stability boundary criterion are met The signal indicates that generator loses static stability due to loss of
excitation Destabilization signal is generated by static stability boundary criterion when rotator low voltage
criterion refuses operation in loss of excitation (if rotator voltage detects open circuit among rotator
windings)
Steam turbine can be asynchronously operated for a period of time in loss of excitation and
overcurrent criterion monitors active power of steam turbine If stator current is more than 1 05 times of
rated current, it indicates that average asynchronous power exceeds 0 5 times of rated power and command
is sent to drive down generator output to enable steam turbine to continue stable asynchronous operation
Stable asynchronous operation generally allows 2 ～ 15 minutes and so the protection sends tripping
command upon time delay Operators can have enough time to shoot troubles and resume excitation during
signaling to avoid tripping, which is of significance to economic operation If output cannot be driven down
within t2 and overcurrent criterion is met, tripping command is sent to ensure the safety of generator