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OGYD-EP
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| BUSBAR DIFFERENTIAL PROTECTION |
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| The complex digital busbar differential protection
of type OGYD-EP is a member of the device family named EuroProt. This short
description contains special data of this type. General and common features
of EuroProt family can be found in the EuroProt system information sheet.
Accordingly it is proposed to study both this short description and the
system information sheet, in order to get a clear picture of this protection. |
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| Application field |
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The busbars used in a high voltage electric
power system play an important role. Since the busbar concentrates the short-circuit
power, destructive effects caused by a fault, by a device failure, by a
handling mistake or by any other reasons are very high. A high speed busbar
protection with high reliability can decrease the damage.
The OGYD-EP type three phase biased busbar differential protection and circuit
breaker failure protection, based on optical fibre cable links can be used
for this aim. Information (currents, voltages, position indications, trips)
from the bay units are sent to the central unit through high speed series
lines of optical fibre cable, in which busbar-selective and independent
measuring relays are assigned to the real busbar configuration. The central
unit performs the bus bar protection evaluation, and detects the failure
of a breaker, and backup trip command is sent to the bay units if it is
necessary. |
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| Main features |
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Functional characteristics:
- one central unit
- one bay unit, per bays
- all currents and other signals are three phase information
- a bay unit is a distance protection or an overcurrent protection of
EuroProt type, where a bay module is installed
- all the bay units are interconnected with the central unit through
high speed series line of an optical fibre cable pair
- each feeder unit sends signals to the central unit as follows:
- three phase currents separately, synchronised in each 1 ms
- information about three phase voltage presence/absence
- two bit position indication ofbusbar disconnect switch of the
feeder
- field breaker failure protection starting
- phase selective signal of the C.H. trip command
- the central unit is of digital design, it has independent main processor
(CPU MAIN) and separate digital signal processor (DSP, called CPU OGYD)
- the central unit sends signals to each feeder unit through optical
fibre cable pair as follows:
- synchronising signal in each 1 ms
- trip commands ifit is necessary
- the central unit is automatically configured according to the information
collected through optical fibre cable pairs, and assigns independent
measuring functions to each busbar sections
- each measuring relay separately calculates its differential (summarised)
current, and its biased current by summarising the absolute values
- the measuring relays make a decision on base of their characteristic
with one knee point
- the special evaluation function operates properly even in case of
high level C. T. saturation
- voltage breakdown condition is necessary to trip
- operating time is 20 ms (see Technical Data in detail)
- the breaker failure protection has two stages, the first stage sends
a trip command again the own C.H., the second stage initiates tripping
of all circuit breaker of the busbar section.
Software characteristics:
- built-in self-check functions
- digital event recorder for 50 events, and an event sequence recorder
with 1 ms time resolution for maximum 300 events
- analogue event records with current data
Hardware characteristics:
- numerical type, with own AID converter, digital signal processor (DSP)
and separate main processor
- there are two designs:
- centralised design, where the central unit and the feeder units
are built in one cabinet
- decentralised design (field design), at which the central unit
is built into one central case and the feeder units are located
at their own field
- opto-coupler inputs
- output contacts
- the type of the contacts (NC or NO) can be selected individually for
each contacts when ordering
- versions for 19" rack cabinet mounting or housed in relay case
(semi-flush mounting or hinged type)
- optional DlGIPROT fault recorder board
Communication:
- 2x16 character LCD display for setting the functions, displaying messages
and reading recorded events
- on-line screen on external PC to make commissioning and testing easier
- external communication interface, can be set for RS 232 or for fibre
optic cable
- optional interface module for SCADA systems
- the parameters can be saved and downloaded
- real time clock handling with the help of RAM with battery, (which
can be synchronised via optical fibre cable connected to external PC,
to the SCADA system)
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| Working principle |
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The digital busbar protection includes one
central unit and bay units for each bays. The bay unit is an EuroProt type
distance protection or overcurrent protection, extended with a signal processing
and optical cable driver board. The bay unit uses the own supply unit, built-in
CT's and analog/digital converter of the EuroProt device. The disconnector
position signals are input via optical coupler boards.
Each bay unit is interconnected with the central unit through high speed
series line of an optical fibre cable pair (transmitter and receiver). Optical
fibre connection is used even if centralised design is applied. The bay
units installed in the feeder bays send the disconnector switch position
indications with two bit signals (open-closed), the three phase voltage
presence or absence, the trip commands given to the feeder CB, and the external
and own breaker failure protection starting in each milliseconds to the
central unit through the high speed optical cable pair. If the position
indications do not change in IO ms, OGYD "configures" itself,
i.e. determines the actual substation configuration, the actual state of
the busbar system, and assigns individual measuring functions to all the
busbar sections.
The central unit sends a synchronizing signal to each bay units through
optical fibre cable pair. The bay units send instantaneous current values
in three phases in each ms to the central unit. The values are processed
by the assigned measuring relay functions of the central unit. The tripping
characteristic of a measuring relay is shown in Figure 1.
Figure 1.
The busbar protection operation can be effective only if the voltage breaks
down in the affected feeder and phase. The algorithm is extended by CT circuit
failure monitoring and optical cable failure monitoring system.
The operation of the digital breaker failure protection built in the OGYD-EP
protection is as follows. The breaker failure protection is assigned separately
for each measuring relays. Only the feeders switched to the busbar by disconnectors
take part in the operation of breaker failure protection.
Each bay unit connected to the busbar section gets the breaker failure protection
starting command, checks whether current flows on the feeder, and whether
there is really trip command to any of the trip coils. If all the conditions
are fulfilled the feeder unit sends message to the central unit without
time delay, that breaker failure is possible on the feeder.
When the conditions of the breaker failure protection are fulfilled, the
central unit starts two timers. One of them sends a command after time delaying
to the relevant feeder unit. If it is still non-effective and the starting
condition of the breaker failure protection is still existing, then after
a longer time delaying all CB's of the bus bar section get the trip command.
The breaker failure protection detects separately in each phase but gives
three phase trip command. |
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| Technical data |
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Rated secondary current, In
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1 A or 5 A |
| Rated voltage (line), Un |
100 V or 200 V |
| Rated frequency |
50 Hz or 60 Hz |
Overload capacity, voltage circuit, thermal, continuous
current circuit, thermal, continuous
1 s |
2xUn/Ö3
4xIn
100xIn (In=1 A), 50xIn (In=5 A) |
| Dynamic current limit |
100xIn |
Accuracy, timers
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± 3 ms (steps 10 ms)
± 12 ms (steps 1 s) |
| Number of opto-coupler inputs |
8-16 |
| Number of output relays |
16 pcs |
| Output contacts type (NC, NO) |
1 NC, 15 NO (or as requested) |
Output contacts, electrical
data:
rated switching voltage
continuous load current
making current
DC breaking capability at 220 V,
at pure conductive load
at load ofL/R = 40 ms
For the trip relays at load of L/R = 40 ms |
250 V
8 A
16 A
0,25 A
0,14 A
4 A |
Auxiliary DC voltage (the same supply unit)
voltage tolerance
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220 V or 110 V
88 V to 310 V |
| Permissible ambient temperature |
0o to 50o C |
| Insulation test (IEC 255) |
2 kV, 50 Hz
5 kV, 1.2/50 µs |
| Disturbance test (IEC 255) |
2.5 kV, 1 MHz |
| Electrostatic discharge (ESD; IEC 801-2) |
8 kV |
| Burst test, (IEC 801-4) |
2 kV |
| Electromagnetic (radio-frequency) interference test |
IEC 801-3 |
| Seting ranges |
| Measuring relay parameters, characteristic data (in
primary value) |
| Basic sensitivity, (I base) |
50-5000 A, step 10 A |
| Bias, (K) |
50-80%, step 5% |
| Max. value of feeder load, (I Offset, "a") |
0-5000 A, step 10 A |
| CT circuit monitoring failure current [CT failure start] |
10-5000 A, step 25 A |
| Measuring relay parameters (connected data per feeders
in the central unit) |
| 1-st feeder, CT primer rated current, (CTPr A) |
50-5000 A, step 25 A |
| 2-nd feeder, CT primer rated current, (CTPr A) |
50-5000 A, step 25 A |
| (n-1)-th feeder, CT primer rated current, (CTPr A) |
50-5000 A, step 25 A |
| n-th feeder, CT primer rated current, (CTPr A) |
50-5000 A, step 25 A |
| Timer parameters |
| CT circuit monitoring timer, operating and drop out
delay [CT failure timer] |
100-32000 ms, step 10 ms |
| CB failure protection, first timer |
0-32000 ms, step 10 ms |
| CB failure protection, second timer |
0-32000 ms, step 10 ms |
| Disconnect switch disagreement protection, timer |
1-60 s, step 1 s |
| Voltage relay parameters |
| Feeder voltage checks |
0,7Un, fixed |
| Communication parameters |
| Eksternal communication |
RS 232/optical cable |
| Eksternal communication, BaudRate |
150 do 19200, step:2x |
| Optical fibre cable operation mode |
radial or loop |
| Substation code |
0-254 |
| Device code |
0-254 |
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| Design, size |
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| An EuroProt device is always rack mounted,
it has two design forms. One of the form is suitable to be mounted into
standard 19" cabinet frame, this form is also suitable to be mounted
directly to a relay panel with flash mounted form. The other form is a relay
panel mounted device with raised-hinged form.
The central unit of the OGYD-EP protection:
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Design
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Width
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Height
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Depth
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Rack mounting
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483 mm
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132,5 mm
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201 mm
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Panel mounting
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490 mm
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250 mm
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250 mm
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The feeder unit of the OGYD-EP protection:
It is a distance protection or an overcurrent protection containing a special
printed circuit board plugged into the protection. |
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