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DTI2-EP
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| DIGITAL OVERCURRENT PROTECTION |
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| The digital complex overcurrent protection
of type DTI2-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 complex overcurrent protection
of type DTI2-EP with independent or dependent time delaying is used in generating,
transmitting and distributing establishments as well as at consumers of
an electric power system on such fields where short circuits, faults or
abnormal operations cause overcurrent exceeding the rated current, hence
the events caused overcurrent can selectively be catched by overcurrent
relays. Typical application field is a protection for short circuit, back
up protection and protection agains overloading. |
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| Main features |
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- the overcurrent protection is designed by phase (3x[I>, I>>];
2x[I>, I>>])
- three or two phase type may be required (3f, 2f)
- the protection may be completed with zero sequence overcurrent relais
(3Io>, 3Io>>)
- the 3Io> design may be completed with zero sequence directional
detection as well (Io j)
- the overcurent relais may be separately set to independent or dependent
characteristic
- the dependent characteristic may be set to normal inverse, very inverse,
extremly inverse and long time earth fault inverse characteristic, according
to the equations as follows:
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Normal inverse
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Very inverse
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Extremly inverse
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Long time earth fault inverse
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t = k * 0,14 / (I0,02-1)
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t = k * 13,5 / (I-1)
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t = k * 80 / (I2-1)
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t = k * 120 / (I-1)
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- by the help of a digital software matrix, each overcurrent relais
starting and the two additional timers can make operating of the output
relais, starting their timers and the two additional timers
- the overcurrent relais may be set in per cent of the main C.T. rated
value, which should be set
- operation field (greatest and smallest angle values) as well as hysteresis
angle range (resetting ratio) of the zero sequence angle relay may be
set
- programming, checking of the protection, reading of the stored events,
receiving on-line informations is possible by a menu system with the
aid of a built in man-machine connection means (six pushbuttons, LCD
display with 2x16 characters)
- its handling may be carried out by an external PC (e.g. by a laptop)
or by a central computer (e.g. SCADA)
- the protection is provided with automatic and manually started self
monitoring system
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| Working principle |
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| Input currents of the device through inductive
auxiliary C.T. and analogue low pass filter go to the multiplexer, and the
S/H, where each phase current and the zero sequence current will be sampled
by 0.5 ms, and each overcurrent stage is separately applied to each input
currents.
The time delaying of the eight overcurrent relais may be independently
set. The high and low setting stages may also be separately set.
Inverse characteristics may be chosen according to the equations written
above.
Arbitrary working range of the angle (e.g. sinj,
cosj, 45°) may be chosen for the directional
earth fault relay (Io j).
Logical connections between the protection units as well as the timers
and the output relais may be programmed by a digital (software) matrix.
A continuous and a periodical monitoring system is buit into the device.
The continuous monitoring system checks the supply voltage. The periodical
monitoring system starts daily in a preset time, and when it is started
by hand with the aid of the Control menu point of the Parametring basic
menu. Both monitoring system gives alarm and automatic message appears
on the LCD display when a fault is found.
If the protection works also a message appears on the LCD display.
The protection workings will be stored by an event log with 50 events
memory, and by an event sequence recorder with 1 ms resolution and 300
events memory. The event log and the event sequence recorder may be read
through series line.
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| Technical data |
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Rated secondary current, In
Rated secondary zero sequence current, In o
(other value can be given when ordering) |
1 A or 5 A
0.1 A, 1 A or 5 A |
| Main C.T., primary current, settable |
50 to 1500 A, steps 15 A |
Zero sequence main C.T.,
primary current, settable
toroidal type C.T., ratio |
50 to 1500 A, steps 15 A
150/5 A |
Overload capacity, continuous
1 s |
4×In
100×In (if In = 1A)
50×In (if In = 5 A) |
| Dinamic current limit |
100×In |
| Accuracy, overcurrent relais (over 50 %) |
± 2 % |
Digital timers, (at step of 10 ms)
(at step of 1 s) |
± 3 ms
± 12 ms |
| Resetting ratio, overcurrent relais (on request, other
value) |
95% |
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Overcurrent relais, setting range in percent of main C.T. primary
current
high and low setting overcurrent relais
zero sequence relais
in case of toroidal type C.T.
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range
50 to 2500 %
10 to 104 %
10 to 104 % |
steps
5%
5‰ |
| Timers, setting range |
0 to 60000 ms |
10 ms |
| Dependent characteristic constant |
k= 0.02 to 1 |
0.02 |
| Additional timer T1, setting range |
0 to 60000 ms |
10 ms |
| Additional timer T2, setting range |
0 to 600 s |
1 s |
External communication
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RS 232/optical fibre cable |
| External communication, transfer speed
(BaudRate) |
150 to 19200, steps 2 times |
| Daily automatic self check, starting time |
0 to 23 hour 59 minute, steps 1 min |
| Automatic self check, blocking |
setting to 60 minute |
Output relais number
(programmable by software matrix)
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8, 12 or 16 pcs
print relais (as requested) |
Output contacts, electrical data:
rated switching voltage
continuous load current
making current
Breaking current at 220 V DC,
pure conductive load
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 |
220 V or 110 V
88 V to 310 V |
| Permissive ambient temperature |
0°C to 50°C |
| Insulation test (IEC 255) |
2 kV, 50 Hz
5 kV, 1.2/50 ms |
| Disturbance test (IEC 255) |
2.5 kV, 1 MHz |
| Electrostatic discharge test (ESD; IEC 801-2) |
8 kV |
| Burst test, (IEC 801-4) |
2 kV |
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| Design, size |
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The digital complex overcurrent protection of type DTI2-EP is an EuroProt
device so it has designs of two different kinds. The one may be put to
a standard cabinet of 19". The other design is an independent relay
case. There are three different sizes for the design suitable to the given
protection and SCADA tasks.Widths are 235, 341 ili 448 mm. Other dimensions
are given in the figure below (hight 250 mm, depth 250 mm).
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| Options |
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- Disturbance recorder
- Interface to a SCADA system
- Output contacts with 4 A DC breaking capability
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| Data to be ordered |
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Type
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DTI2-EP
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3f
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I0
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12K
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8D
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(example)
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Pc. of phases
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Earth fault prot.
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Pc. of output contacts
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Pc. of digital inputs
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- Rated current [1 A, 5 A]
- Feeding of zero sequence relais [main C.T., toroidal type C.T.]
- Whether is the logical (d.c.) busbar protection contact an NC or NO
type?
- Options [if needed]
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