Simple very high-speed overcurrent protection relay
Приведено описание и представлены результаты экспериментальных исследований быстродействующего гибридного реле тока с чувствительным органом на герконе. Показано, что такое реле может быть с успехом использовано для ускорения действия основной релейной защиты....
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Інститут технічних проблем магнетизму НАН України
2007
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| Назва видання: | Електротехніка і електромеханіка |
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Simple very high-speed overcurrent protection relay / V. Gurevich // Електротехніка і електромеханіка. — 2007. — № 1. — С. 13-16. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-1428202018-10-17T01:23:32Z Simple very high-speed overcurrent protection relay Gurevich, V. Електричні машини та апарати Приведено описание и представлены результаты экспериментальных исследований быстродействующего гибридного реле тока с чувствительным органом на герконе. Показано, что такое реле может быть с успехом использовано для ускорения действия основной релейной защиты. Приведено опис і представлення результатів експериментальних досліджень швидкодіючого гібридного реле струму з чутливим органом на герконі. Показано, що такі реле може бути з успіхом застосовано для прискорення дії основного релейного захисту. Specification and results of experimental research on a high-speed hybrid overcurrent relay with a reed switch as the sensitive element are given. It is shown that this relay can be successfully used for acceleration of the basic relay protection action. 2007 Article Simple very high-speed overcurrent protection relay / V. Gurevich // Електротехніка і електромеханіка. — 2007. — № 1. — С. 13-16. — Бібліогр.: 3 назв. — англ. 2074-272X http://dspace.nbuv.gov.ua/handle/123456789/142820 621.316.925 en Електротехніка і електромеханіка Інститут технічних проблем магнетизму НАН України |
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Електричні машини та апарати Електричні машини та апарати |
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Електричні машини та апарати Електричні машини та апарати Gurevich, V. Simple very high-speed overcurrent protection relay Електротехніка і електромеханіка |
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Приведено описание и представлены результаты экспериментальных исследований быстродействующего гибридного реле тока с чувствительным органом на герконе. Показано, что такое реле может быть с успехом использовано для ускорения действия основной релейной защиты. |
| format |
Article |
| author |
Gurevich, V. |
| author_facet |
Gurevich, V. |
| author_sort |
Gurevich, V. |
| title |
Simple very high-speed overcurrent protection relay |
| title_short |
Simple very high-speed overcurrent protection relay |
| title_full |
Simple very high-speed overcurrent protection relay |
| title_fullStr |
Simple very high-speed overcurrent protection relay |
| title_full_unstemmed |
Simple very high-speed overcurrent protection relay |
| title_sort |
simple very high-speed overcurrent protection relay |
| publisher |
Інститут технічних проблем магнетизму НАН України |
| publishDate |
2007 |
| topic_facet |
Електричні машини та апарати |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/142820 |
| citation_txt |
Simple very high-speed overcurrent protection relay / V. Gurevich // Електротехніка і електромеханіка. — 2007. — № 1. — С. 13-16. — Бібліогр.: 3 назв. — англ. |
| series |
Електротехніка і електромеханіка |
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AT gurevichv simpleveryhighspeedovercurrentprotectionrelay |
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2025-07-10T15:49:46Z |
| last_indexed |
2025-07-10T15:49:46Z |
| _version_ |
1837275638703063040 |
| fulltext |
13 Електротехніка і Електромеханіка. 2007. №1
УДК 621.316.925
SIMPLE VERY HIGH-SPEED OVERCURRENT PROTECTION RELAY
Gurevich Vladimir, Ph.D
Israel Electric Corp., Central Electric Laboratory
POB10, Haifa 31000, Israel
fax: (++1) 603-308-5909, e-mail: gurevich2@bezeqint.net
Приведено опис і представлення результатів експериментальних досліджень швидкодіючого гібридного реле струму з
чутливим органом на герконі. Показано, що такі реле може бути з успіхом застосовано для прискорення дії основного
релейного захисту.
Приведено описание и представлены результаты экспериментальных исследований быстродействующего гибридного
реле тока с чувствительным органом на герконе. Показано, что такое реле может быть с успехом использовано для
ускорения действия основной релейной защиты.
Overcurrent and overload protection functions for
both low-voltage and high-voltage consumers of electric
power (and also electric networks) are usually realized on
current relays with dependent or independent time delay
characteristics, or on high-speed differential relays or
impedance (distance) relays (for power line protection). In
some situations, however (at close short circuits and high-
power sources), the multiplex overcurrent passing through
the protected object is capable of causing destruction of the
object, even when it is protected with one of the above-
mentioned protection relays. For such cases special very
high-speed relays are stipulated. Usually the time delay of
such high-speed relays, both electromechanical (for
example, KO-1, produced by АВВ) and microprocessor-
based (for example, SEL-551C from Schweitzer
Engineering Laboratories, BE1-50 from Basler Electric,
RCS-931A/B from NARI, etc.) is within 20 to 40
milliseconds (as stated by manufacturers). In addition,
electromechanical protection relays with instantaneous
pick-up characteristics frequently provide even higher
speeds (18-25 мс), than microprocessor-based relays.
Promotional materials may sometimes be found
which claim that an especially constructed high-speed
microprocessor relay is capable of operating with a time
delay of less than one period (less than 20 мс), Fig. 1.
Fig. 1. Oscillogram of operation of a high-speed microprocessor
relay of the SEL-487B type. According to promotional materials
its operation time is less than 20 milliseconds
Such small operating time delays really can be
realized sometimes for microprocessor relays with
injection of high current with an artificially fixed phase
for the first half-cycle (as on the oscillogram, Fig. 1).
Unfortunately in practice such extreme artificially created
conditions are rarely achieved, therefore such unique
operation times look more like an advertising gimmick
than a parameter provided under real operating
conditions.
Many companies are engaged in development and
production of actual high-speed relays. The analysis of
real transients of short circuits with high DC components
and strong CT saturation has brought some researchers to
the conclusion that it is impossible to provide relay
protection for operating times of about one half-cycle (10
ms). These researchers offer a new algorithm based on
measurement of first (di/dt) and even second (di2/dt)
current derivatives. In reality, experimental oscillograms
of transients (Fig. 2) confirm the stability of such
parameters as a current derivative (speed of change of
current, or in other words an inclination angle of the front
of the first pulse of a current at short circuit) even with
high DC components contained in the current. On the
basis of these researches one of the Israeli companies has
developed a microprocessor relay with this algorithm.
Thus the relay has turned out to be relatively complex
because measurement of only the second current
derivative is insufficient for realizing necessary relay
stability.
Fig. 2. Shows relation between the CT secondary current,
applied to input of the relay and secondary ratio current at close
short circuit mode
Inserting special elements for blocking of excessive
relay operations is required because of the excessive
sensitivity of the relay to some operating modes, as revealed.
In addition, as the current derivative depends on a relation
between an initial current before failure and a pickup current
Електротехніка і Електромеханіка. 2007. №1 14
at failure, it appeared that the relay does not always work
properly if relative high load current is preceded to failure
mode, and vice versa, excessive relay operations sometimes
take place for great current changes (from zero value up to
high values, but less of pickup value).
Despite some technical problems, preliminary tests
of the relay prototype have confirmed its high speed. For
the most difficult cases the time delay displayed was 8.4
мs, which it is much less than any microprocessor relays
existing today in the market. The EMI compatibility and
some other important relay parameters have not been
investigated yet; nevertheless, the possibility of creation
of the overcurrent microprocessor relay with an operation
time of about a half period has been confirmed.
The author offers an alternative variant of a very
simple and low-priced high-speed overcurrent relay with
an algorithm based on measurement of
instantaneous value of a current. The relay is so simple
that it can be produced by the own staff of power systems.
The offered overcurrent relay is based on a reed switch
[1], with a high-voltage thyristor as an electronic
amplifier, Fig. 3.
Fig. 3. Basic circuit diagram of a simple very high speed
overcurrent relay on reed switch
The basic sensitive element in this device is the reed
switch, which begins to vibrate at a pickup with frequency
of 100 Hz. Its first pulse opens a powerful thyristor SCR,
which energizes a circuit breaker trip-coil. The thyristor
remains in the conductive condition, despite reed switch
vibration, so long as the circuit is not turned-OFF by
auxiliary contact of the circuit breaker. An addition
auxiliary relay with a low impedance current coil and a
spark protected power reed switch may be used for
energizing of external electromechanical relays of
automatic or signal systems. Subminiature high-voltage
vacuum reed switches of the MARR-5 (Hamlin) or MIN-
21 (Binsack Reedtechnik GmbH) types, with
withstanding voltage of 1.5-2 kV and turn-ON times of
not more than 0.6-0.7 ms, are used as metering elements
that provide high reliability of the relay. A thyristor of the
30TPS16 type was also chosen with a large reserve for
current (30А) and for voltage (1600 В), allowing to
choose for protection from overvoltages the varistor RV,
also having a large reserve (clamping voltage of about
800 VDC) regarding rated voltage (220VDC), providing
both higher reliability and longer durability.
The reed switch module [2] can be provided with
different methods of pickup adjustment: by means of a
moving reed switch inside the coil, or by using different
modules with different fixed values of pickup current.
The last variant is quite acceptable, as this module is very
simple and low-priced. After adjustment of the reed
switch position in the coil, it must be fixed by means of
silicon glue.
Output auxiliary relays are also made as reed relays
(without adjustment) because their winding is not
standard relay winding, but is designed as current winding
(80–100 turnings) for current values suitable to the trip
coil of circuit breakers. For such purpose power reed
switches can be used, for example R14U, R15U
(Yaskawa Electric America); MKA-52202 (Russia); GC
1513 (Comus Group); DRT-DTH (Hamlin), provided
with spark protection (RC-circuit).
The prototype model of a 10А pickup reed switch
module (Fig. 4) without a thyristor amplifier (thyristor
switch-ON time is less than 10 µs, which does not affect
in any way the general time delay of the device) and
without an auxiliary relay, has been submitted to tests.
Fig. 4. Unit of reed switch, submitted on tests with rated pickup
current of 10A
Tests were performed by artificial simulation of
various modes on a current by means of a Power System
Simulator F2253 (DOBLE Engineering), and also by
injection in the module, by means of the same simulator,
of real secondary currents of short circuit transients
restored from COMTRADE files of the real failures in
160 kV power network, extracted from microprocessor-
based transient recorders.
In the first series of experiences operation time of
the module was measured at instant change of current on
an input of the module in a range from 0.2–0.8 IPICKUP up
to 1.2–5 IPICKUP, with various random phases of current
transition and also with a zero phase of current sinusoid,
Fig. 5. The tests verified that the lower limit
predetermined current value preceded to pickup current
does not affect operating time (Fig. 6), as against
microprocessor based relay reactions to current
derivatives.
Research also affects harmonics (contained in a
current) on operating time at different phase transitions of
a current, Fig. 7, and verified that even the high
harmonics content does not affect operating time.
The main factors are still the phase and magnitude of
a current transient. For the most difficult case, that is at
small current I = 1.2IPICKUP and with switching current
phase at close to 45º, maximal operation time can reach
7–8 ms.
15 Електротехніка і Електромеханіка. 2007. №1
Fig. 5. Some oscillograms of operation of reed switch unit at
instant change of current with various phases of current
transition. Non-operating zones of the relay are marked
Fig. 6. Oscillogram of operation of relay with previous
non-operating current (9 А), near to a pickup (10 А)
Heavier testing appeared for real secondary currents
of short circuit transients contains a high DC component,
causing displacement of a sinusoid of current concerning
an axis, Fig. 8. The maximal operation time fixed at these
tests reach 9.4 ms. In addition, in some experiences with
high DC components, pickup current decreased by as
much as 0,7 of the rated pickup current. This occurred
when the relay pickup phase occurred at the moment
corresponding to the maximal displacement of the first
half wave of a current sinusoid. For such conditions relay
picked up at much smaller current than at a normal
sinusoid in the continuous mode. In our opinion, this
phenomenon is not so essential, as the basic purpose of
such high-speed relays is not exact current measure, but
only detection of the presence of a dangerous short circuit
for acceleration of action of basic relay protection. In
other words, at adjustment of the relay for a primary
current, for example, 20 кА, it is possible to achieve
pickup in some cases at a current of 14 кА that also
specifies a dangerous short circuit, as well as pickup of a
20 кА current. Nevertheless, in some cases this
phenomenon can limit application of reed relays.
Fig. 7. Oscillograms of operation of relay at high harmonic content
in current (for contents of the third harmonic of 7.5 % and 20 %)
Due to use of the reed switch as a sensitive threshold
element, the high speed overcurreent relay developed is not
only very simple, low-priced, and accessible to
manufacturing even by technicians, but also high steady to
external electromagnetic influences: to distortions of a
current, to voltage spikes, to powerful high-frequency
radiations [3], etc. Such sensitive elements on a reed switch,
adjusted on operation at the high rate of a current, can be
built-in also in various microprocessor protection relays (or
can be connected to them outside, through a separate input)
as the bypassed element of the microprocessor for
accelerator tripping of the circuit breaker.
CONCLUTIONS
1. Development of a high-speed overcurrent relay
with a time delay of up to 10 ms for acceleration of action
of main protection is an actual problem.
2. The algorithm for the microprocessor-based over-
current relay which provides real operating time within
the one half-cycle of a current is now known.
3. Use of the reed switch as a sensitive component of
high speed overcurrent relays is a prospective direction
allowing creation of simple and at the same time,
competitive relays, for the purpose of revealing close
short circuits and acceleration of action of basic relay
Електротехніка і Електромеханіка. 2007. №1 16
Fig. 8. Oscillogram of operation of the relay for actual short
circuit transients containing a high DC component
Fig. 9. Principle of winding-free overcurrent reed relay.
1 – current carrying bus bar; 2 – reed switch with pickup
depends on distance X from the bus bar and on angle α for
longitudinal axis Y
Fig. 10. Design of high-voltage overcurrent reed relay not
requiring CT: 1 - main insulator; 2 - fixative plate; 3 - inside nut; 4
- semi-conductive cover; 5 - bushing; 6 - fixative nut; 7 - fastener;
8 - reed switch; 9 - high-voltage bus bar; 10 - epoxide compound
Fig. 11. External view of high-voltage (24 kV) overcurrent reed
relay not requiring CT
REFERENCES
[1] Gurevich V. Protection Devices and Systems for High-
Voltage Applications. – Marcel Dekker, New-York, 2003,
304 pp.
[2] Gurevich V. Electric Relays: Principles and Applications. –
CRC Press (Taylor & Francis Group), Boca Raton-London-
New York, 2005, 704 pp.
[3] Gurevich V. Electromagnetic Terrorism: New Hazards. –
Electrical Engineering & Electromechanics, 2005, No. 4, pp.
81- 83.
Поступила 10.03.2006
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