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INS - 1T
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| DIRECTIONAL OVERCURRENT
RELAY |
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| Application |
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The INS-1T device, is intended for directional overcurrent protection
of networks with isolated, compensated, low resistance earthed and directly
earthed neutral.
The relay input information is a phase current and the line voltage, which
is in normal circuit conditions, perpen- dicular to this current.
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| Description |
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The directional overcurrent
relay receives information on voltage from a voltage measuring transformer
while information on current is received from a current measuring transformer.
According to the block diagram in fig. 1, information on current goes to
the current comparator 1> in which the required pick-up current setting
is effected (in the range of 0,6 to 1 ,8 Ir) .
Information on current direction is formed through serving both voltage
and current zero crossings. The zero crossing of voltage triggers a monostable
multivibrator circuit which generates a square wave pulse at its output
of duration b, adjustable from 0,55 ms to 10
ms. The falling edge of the square wave pulse having duration b
triggers the next monostable multivibrator circuit which generates a square
wave pulse of duration h = 10 ms.
If the instant of zero crossing of current falls within the interval h
, that means that the current laggs behind the voltage for the time equal
to at least b .Considering that the lagging time
corresponds to phase shift, the durati- on b
is calibrated in degrees directly (and can be set from 10° to 180°). A graphical
interpretation is presented in fig. 2. With voltage and current measuring
transformers connected as in fig. 1, the angle b
can be defined as the angle existing between voltage and the "nearer"
limit of the relay pick-up zone (having the "width" of 10 ms,
resp. 180° ). It is therefore possible, by selecting b
, to select an arbitrary position of the re ay pick-up semi-plane in the
plane U, I and thus match the relay optimally to network conditions.
In the example on fig. 2, it is visible that fault current I1, falls within
the relay pick-up zone. |
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| Features |
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The INS-1T relay is
made with high quality and reliable semiconductor components. Static construction
has offered high reliability, accuracy and sensitivity. The sensitivity
does not depend on the angle between current and voltage. The relay operation
is normal at 1% Un.
The choice of pick-up current settings and of pick-up zone positions of
the relay is possible within wide limits by means of the setting elements
on the relay front panel.
In the text b [ms] is calculated for the rated
frequency of 50Hz. |
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| SPECIFICATIONS |
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Rated current
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5A
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| Current overload |
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continuous
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10A
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6 s
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50A
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| 3 x 1s |
150A
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| Rated frequency |
50 or 60 Hz
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| Rated voltage |
100V, 110V, 120V
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| Voltage overload |
250V
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| Setting range |
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| I> |
(0,6-1,8) In
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| t> |
(0,2-6)s
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| b |
10o - 180o
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Accuracy of scales
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| I> |
5%
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| t> |
5% for t> 1s
50ms for t<1s
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| b |
5o
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| Sensitivity voltage threshold: |
1 V
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| Power drain |
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| From the current path |
0,5 VA
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| From the voltage path |
0,3 VA
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| From the auxiliary source of supply |
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| at 110 V DC |
7W
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| at 220 V DC |
14W
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| Auxiliary supply voltage from a storage battery or regulated |
110V DC, 220V DC
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| Supply source |
-15%, +10%
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| Contacts |
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| Maximum voltage |
250V
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| Continuous current |
5A
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| Current ata make |
10A
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| Breaking capacity |
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| for cos j = 1 |
1000 VA
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| for DC at L/R = 40 ms |
20 W
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| Ambient temperatrure |
-10oCšš +50oC
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| Tast voltage |
2 kV; 50Hz; 1 min.
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| Mass |
1,9 kg approx.
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| Dimensions |
as in fig. 3
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| How to order |
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- type of unit
- auxiliary voltage
For all inquiried please contact the manufacturer.
Subject to change without prior notice..
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