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INH
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| RELAYS FOR OVERCURRENT AND
HOMOPOLAR PROTECTION |
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| Application |
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The relays for overcurrent and earth-fault protection, type INH are intended
for selective protection of single-side powered (radial) overhead and
cable lines, generators and transformers from overload, short circuits
and asymmetric loads (as a consequence of accidental ground of a live
part of the plant, earth-fault, asymmetric load on consumer end, etc.).
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| Description |
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| Overload protection |
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| With an input current exceeding
the permissible value (having continual settings in the range from 0,6 In
to 1 ,8 In) for longer than the setting on the time scale, the output relay
will be activated and a command released for the circuit breaker tripping.
The time delays of the time scale have continual settings from 0,2 s to
6 s. |
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| Short circuit protection |
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| With an input current exceeding the value set
on the scale of short circuit protection (with settings in the range from
3 In to 10 In or 5 In to 25 In for N option respectively), the output relay
will be activated practically instantaneously and a command released for
the circuit breaker tripping. With an input current ranging between 1 ,8
In and 3 In (5 In for N option), the operation of the overcurrent relay
is same as for the case of overload protection. |
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| Homopolar protection |
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With an input homopolar current exceeding the
value set on the scale of homopolar protection (with settings in the range
from 0,1 In to 1 In) for longer than the setting on a time scale, the output
relay will be activated and a command released for the circuit breaker tripping.
The devices for overcurrent and homopolar protection, type INH are. self-contained
units of the Automatic Control System for Transformer Stations - SAUT. Same
as other units of that System, the relays type INH are static relays and
have independent time lag characteristics.
In a most complex arangement, the unit comprises a comparator for overload
currents, a comparator for short circuit currents, a comparator for homopolar
current and a time delay member which is common for both overcurrent and
homopolar current comparator.
The relay receives information on current magnitude from current instrument
transformers wired into appropriate phases of the protected plant, or from
jaw-type transformers. The information is then processed in the measuring
circuit, and depending on the amount and the position of potentiometers
I > (in the range from 0,6 In to 1 ,8 In, Ih > (in the range from
0,1 In to 1 In), and I >> (in the range from 3 In to 10 In or 5 In
to 25 In respectively), the compara- tors I > , Ih > or I >>
can have operated.
The operation of the comparators I > and 1h > (see fig. 7) results
into:
- an instantaneous activation of the auxiliary relay the contacts of
which (12-13 normally opened) are usually wired to operate the automatic
reclosing unit (APU) and for signalling;
- an activation of the final control relay with closing of the contacts
17 -18, 19-20 and 21-22 after expiration of the time delay set on the
scale t > in the range of 0,2 to 6 s.
With an overload current I > , or Ih > occuring shorter than the
time set on the scale t > , the relay "b" and the time member
t > return instantaneously to their initial state, so the time member
will not activate the output relay.
The operation of the comparator I >> results into:
- an instantaneous operation of both the above relays.
The scales I>, Ih>, I>> and t> are logically arranged,
easily accessible, clearly marked and ggraduated and can be set continually.
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| Features |
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The overcurrent relays, type INH are all solid-state
units (static construction) distinguished by their rehability and accuracy,
very good pick-up to drop-off ratio, low power drain and practically unlImited
lIfe.
In addition to homopolar member, the relays, type INH can incorporate the
protection for one, two or three phases, what is achieved by repeating certain
assemblies in the unit. Considering that the current response magnitude
is same for all phases, INH relays have four, respectively three scales
with continual settings:
- a scale for overload protection current I >
- a scale for homopolar protection current Ih >
- a time delay scale t >
- a scale for short circuit protection current I >
When the unit for overcurrent and homopolar protection is applied for
polyphase protection (most usual case), it will respond as soon as the
current In any protected phase exceeds the set value.
The units for overcurrent and homopolar protection are equipped with an
instantaneous contact (terminals 12-13 in fig. 3) which makes them possible
to be coupled with the automatic reclosing unit (APU). The units, type
INH are powered from the source of auxilIary power 110 V DC or 220 V DC.
The units, type INH 300 V and INH 340 (V and C) as well as the units option
N are housed into the box I 41 ( see dimensional drawings in figs. 20
and 21 ), while all other units type INH are housed in the housing H 21
(see the dimensional drawings in figs. 22 and 23).
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| Method of coding |
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The relays type INH represent a line of overcurrent and homopolar relays
with definite time lag characteristic, manufactured by "Energoinvest"
The symbol INH denotes that, in addition to overcurrent protection, the
unit contains the homopolar current protection number. Following the INH
symbol, each relay type is denoted by the symbols on four subsequent places:
The following symbols can be found on individual places:
0 - denotes that overload protection member is not contained in any phase
(only homopolar member contained).
1 - denotes that overload protection member is contained In one phase.
2 - denotes that overload protection member is contained in two phases
3 - denotes that overload protection member is contained in three phases
Place II
0 - denotes that no short circuit protection member I >> is contained
4 - denotes that the short circuit protection member I >> is contained
Place III
0 - denotes that no phase failure signalling Is contained
Place IV
Standard construction:
V - external power supply
On request:
C - the unit is equipped with a separate output relay for the member
I >, the contacts wired to terminals 14 and 15 (figs. 4 and 8), and
terminals 23-24, 25-26. 27-28 (fig. 12)
N - the unit is equipped with separate output relays for the members I
>, Ih >, I > (or Ih > ) + + t > and I >>,
Example:
INH - 240 - Overcurrent and homopolar relay type INH with definite time
lag characteristics, containing the homopolar protection member, the overload
protection member I > in two phases,. the short circuit protection
member I >>, without phase failure signalling.
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| SPECIFICATIONS |
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Rated current
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5A, 1A
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| Overload current setting range (I>) |
0,6 In to 1,8 In
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Homopolar current setting range (Ih>)
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0,1In to 1 In
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Short circuit seting range (I>>
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3 In to 10 In)
(za N varijantu 5 In to 25 In)
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| Accuracy of current setting |
5%
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| Time delay setting range (t>) |
0,2s to 6s
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| Accuracy of time setting scale |
better than 50 ms for t<1s
5% for t>1s
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| Pick-up for drop-off ratio |
in excess of 0,9
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| Power taken per phase at In = 5A |
less than 2 VA
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| Power drain from auxiliary |
at 110V= 6,5 VA
at 220V = 13VA
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| Supply voltage of storage battery or regulated
source of supply |
110V=, 220V=,
-15% +10%
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Contact ratings
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| Maximum voltage |
250V
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| Continuous current |
5A
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| Current at make |
10A
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| Breaking power at cosj
= 1 |
1000 VA
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| at DC with L/R = 40 ms |
20W
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| Ambient temperature limits |
-10oC to +50oC
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| Test voltage |
2 kV, 50 Hz, 1 min.
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| Mass |
with housing I 41 7 kg approx.
with housing H 21 3 kg approx.
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| Dimensions |
according to figs. 20 - 23
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| How to order |
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- type of relay
- rated current
- auxiliary voltage
For any details please contact the manufacturer.
Subject to change without prior notice.
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