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DFTK-EP
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| DIGITAL FREQUENCY DEPENDING
LOAD SHEDDING RELAY |
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| The digital frequency depending load shedding
relay of type DFTK-EP is part of 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 system
information sheet too, in order to understand the device entirely. |
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| Application field
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| The digital frequency depending load shedding
relay of type DFTK-EP is applied on large power system to avoid dangerous
system frequency drop and consequently system breakdown when power plant
generators drop out. The frequency relay stages shed (switch off) loads
which are pre-programmed on a tripping software matrix. |
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| Main features |
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- Four independent frequency stages or three frequency stages and one
rate-of-change frequency stage (df/dt) combined with underfrequency
detection
- Underfrequency or overfrequency relay for first three stages, underfrequency
only for forth
- Separate blocking feature for any stages
- Very high frequency accuracy ((±0,005 Hz)
- Large frequency and delaying setting range set table separately for
each stage
- Settable release margin (hysteresis)
- Three voltage inputs with priority circuit
- Operation blocking on break-down of all the three voltages
- Consumer-friend modern digital parametering (setting) method
- Fast checking possibility of the protection setting data
- Password protection against unauthorized setting action
- Fast inquiring possibility of actual frequency data and sum of protection
working counters
- 8, 16, 24 or 32 output contacts by the order, programmable by software
matrix, to set separately individual loads for shedding on some frequency
stage
- 8 digital optical couplers
- Real time clock handling synchronizable by external PC or by GPS worId
time synchroniser
- RS 232 or optical fibre cable for external communication
- Immediately appearing "messages" on occurring protection
events
- Event recorder with 50 protection events with real date and time
- Cancelling all events by hand may be made by external PC only
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| Working principle |
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Voltage sample frequency is 1 kHz. A frequency
relay determines the frequency value as an average of four cycles by an
algorithm calculating the measuring value in each cycle. Each of the three
first stages can be under- or over frequency relay depending on setting
value of limiting frequency. If it is set higher than its setting frequency
value, the stage is underfrequency relay, and if it is set lower, the stage
is an overfrequency relay. The forth stage may be set to under frequency
stage only (if the rate-of-change frequency relay is set to zero), or to
under frequency and rate-of-change frequency relay.
The releasing margin (hysteresis) has to be set to avoid an unpleasant effect
on frequency fluctuation and a unwanted detection on actual operation frequency.
All the four stages has separately an independent timer.
The trip coils of customer C.B.'s which are intended to take part in the
load shedding action may be separately connected to the output relays of
digital frequency depending load shedding relay. The drivers of this relays
may be independently controlled by a set table tripping software matrix.
Setting (parametering) and checking of protection, inquiring of the working
data, events and signals, setting of tripping software matrix, and handling
of automatic signals (messages) is possible with a built-in LCD of 2x16
characters and six push-buttons on interactive mode by the aid of a menu
system or with an external PC. A handling program is delivered together
with the DFTK-EP digital frequency depending load shedding relay to make
handling functions possible by an external PC. |
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| Technical data |
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| Rated secondary voltage, Un |
100 V, 200 V or other |
| Voltage range to accurate frequency measurement |
(0,4-1,3)xUn |
| Overload capacity, thermal, continuous |
1,3xUn |
| Rated frequency |
50 Hz |
| Setting ranges |
| Voltage relay |
40-90 V |
| Frequency relays |
45-55 Hz, step 0,01 Hz |
| Hysteresis |
0,02-0,2 Hz |
| Limiting frequency |
45-55 Hz, step 0,01 Hz |
| Rate of change frequency relay (df/dt) |
0-10 Hz/s, step 0,1 Hz/s |
Each frequency relay, pick up timer
reset timer |
0-50 s, step 0,05 s
0-1,5 s, step 0,15 s |
| Self-check monitoring system, signal timer |
0,1-10 s, step 0,02 s |
| Blocking a frequency stage |
Setting to limiting frequency |
Accuracy, frequency relay
rate of change frequency relay
timers
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± 0,005%
± 0,05 Hz/s
± 2 ms |
| Principle operating time without time delay |
80 ms |
| External communication type |
RS 232/optièki kabl |
| External communication speed (BaudRate) |
150 to 19200 |
| Daily automatic self-check time |
0 to 23 h 59 min |
| Automatic self-check, block |
Setting to 60 min |
| No. of substations within a system |
0-253 |
| No. of devices within a substation |
0-253 |
Number of output relays (number required with order)
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8, 16, 24 or 32 pcs print relays
from them 1 NC, all the others NO |
Output contacts ratings:
rated switching voltage
continuous load current
switching on current
breaking current at 220 V dc,
pure conductive circuit
L/R = 40 ms load |
250 V
8 A
16 A
0,25 A
0,14 A |
Auxiliary DC voltage (the same supply unit)
voltage tolerance
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220 V or 110 V
88 V to 310 V |
| Permissive 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 |
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| Design, size |
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The DFTK-EP digital frequency depending load
shedding relay is a member of the device family EuroProt. It has two different
designs, the one is a device for rack mounting to a 19" standard cabinet
frame, the other is a flash mounting or raising mounting device to a panel.
Its size depends, of course, on the design chosen. The protection is controlled
by microprocessors and equipped with module system of plugged in PCB's,
set up of IC's.
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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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Weight 8 kg. |
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| Information required with order |
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- Type of relay [DFTK-EP]
- Rated V.T. secondary voltage [100 V, 200 V]
- Auxiliary d.c. voltage [220 V, 110 V, 48 V]
- Cases
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