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| Transformer protection panelPower transmission
is done through remote route between power
station and receiving-end. And the efficiency of
transmission is directly related to an economic
feasibility. |
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| Thus, generation voltage is stepped up and
transmitted to receiving-end through remote grid.
At a receiving-end, through stepping down, a
power gets supplied while caring safety of
distribution network and power customer. |
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| This process of step up and step down is done
by power transformer that which is one of the
power facilities. Power transformer is important
because it influences efficiency, safety, and
stability of power transmission. |
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| Power transformer is not only one of expensive
power facilities which need long time for
maintenance and contains multiple potential
problems. Problem of power transformer can
lead outage of power customer. Thus power
transformer protection is directly related to power
quality issue, making reliability important. |
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| Protection relay needed for protection of
transformer has current differential function as
main protection. And for back up protection, over
current protection is used in each primary side
and in secondary side. Especially in secondary
side, for NGR protection, ground over voltage
protection relay is applied. |
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| GABO’s transformer protection panel has a main
protection relay 7UT6x made from SIEMENS, in
order to guarantee reliability. By having
accumulated knowledge in manufacturer
technology of protection panel, and experienced
professionals, we strive to accomplish noise
immunity, stable earthing, durability, insulation,
assembly, all of which being incorporated in
order to generate products of credibility. |
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TRANSFORMER PROTECTION SYSTEM CONFIGURATION |
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| Transformer protection relay measures current of primary and
secondary current, and by using the measurement, it calculates
restraint current and differential current. Thus transformer protection
relay decides any existence of transformer internal/external fault by
using ratio current differential relaying function. |
| In a transformer, depends
on number of winding, it is
divided into 2 winding and 3
winding transformer. And
current differential relaying
function gets calculated by
sum of all winding’s current. |
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TRANSFORMER PROTECTION RELAY (7UT6x) |
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| - Digital Protection Relay with 32 Bit high-speed microprocessor. |
| - Up to 5 winding transformer current differential protection. |
| - Stable Dual-Slope characteristics |
| - Phase shift automatic compensation by using 12 Matrix. |
| - Automatic compensation on primary and secondary currency mismatch by using transformer’s a rated current. |
| - Magnetizing inrush current detection through second harmonic blocking element. |
| - Current auto-compensation to CT saturation and CT ratio error, tap changer. |
| - Convenient function such as Remote setting/ Fault analysis by software. |
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TRANSFORMER PROTECTION RELAY (7UT6x) RATIO DIFFERENTIAL CHARACTERISTICS CURVE |
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| A ratio current differential characteristic for transformer
protection is divided into trip area and non-trip area by ratio
between restraint current (scalar sum) and that of differential
current (vector sum). |
| In case of transformer protection, it uses phase compensation
decided from primary and secondary winding connection.
Phase compensation uses vector group such as 30 [deg] x 12
in order to compensate phase difference and to prevent maloperation
by zero sequence current. |
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TRANSFORMER MAGNETIZING INRUSH CURRENT DETECTION |
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| A magnetizing inrush current occurs when circuit breaker gets closed and transformer becomes initially energized. |
| This magnetizing inrush current
occurs in primary side and does
not pass on to secondary side,
which causes differential current
between two sides. The differential
current function needs a function
that prevents mal-operation
caused by magnetizing inrush
current. |
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TRANSFORMER PROTECTION RELAY (7UT6x) TECHNICAL STANDARD/SPECIFICATION |
| Index |
Item |
Specification |
Remarks |
| Rating |
Power Supply |
Voltage Input |
DC : 125[V], AC : 230[V](Frequency 50/60[hz]) |
Selectable |
| Power Consumption |
20[W] ~ 28[VA] |
| Analog |
Current |
1[A], Burden : 0.05[VA]
5[A], Burden : 0.3[VA] |
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| Power |
80/125[V], Power Consumption ≤ 0.3[VA] |
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| Digital input |
Number of digital input : 3 ~ 29
Voltage Range : 88 ~ 300[VDC] |
Selectable |
| Digital Output |
Number of digital output : 4 ~ 24
Allowable Current : Continus(5[A]), 30[A](0.5[sec]) |
| Communication |
Communication Port |
RS-232, RS-485, Ethernet, FO(Fiber Optic) |
Selectable |
| Protocol |
Profibus, DNP3.0, IEC61850, TCP/IP |
| Time Synchronization |
DCF77/IRIG-B/SNTP |
Selectable |
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