EP2620959A1 - Transformateur de mesure de tension - Google Patents
Transformateur de mesure de tension Download PDFInfo
- Publication number
- EP2620959A1 EP2620959A1 EP12152587.7A EP12152587A EP2620959A1 EP 2620959 A1 EP2620959 A1 EP 2620959A1 EP 12152587 A EP12152587 A EP 12152587A EP 2620959 A1 EP2620959 A1 EP 2620959A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- voltage
- voltage measuring
- resistance
- measuring transformer
- ferro
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/24—Voltage transformers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
- H01F27/422—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers
- H01F27/425—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers for voltage transformers
Definitions
- the invention relates to a voltage measuring transformer for transforming a high voltage into a low voltage, which transformer comprises:
- the invention relates in particular to voltage measuring transformers or potential transformers which are used in power distribution.
- voltage measuring transformers are typically used to reduce a high voltage of several kilo-voltage down to typical voltages of for example 100 V. This enables one to measure high voltage at low voltage level
- a known phenomenon with voltage measuring transformers is the occurrence of ferro-resonance. Due to ferro-resonance, the current can increase out of control, damaging the voltage measuring transformer due to overheating.
- Ferro-resonance is typically initiated when the following elements are present:
- EP 1727257 describes the use of a tertiary coil on the low voltage side of the transformer to provide a damping or load to dampen possible ferro-resonance.
- This publication proposes a load consisting of a positive temperature coefficient thermistor in series with two other resistances.
- the positive temperature coefficient thermistor will warm up and provide additional resistance, damping and clearing the ferro resistance.
- the current on the high voltage side of a transformer is typically small. Only when ferro-resonance occurs, the current will increase rapidly. By having means for increasing the resistance upon such an occurrence, the ferro-resonance can be damped.
- the means for increasing the resistance will have no effect during normal operation. This ensures that voltage measurements can be conducted at high accuracy.
- the means for increasing the resistance comprise at least a positive temperature coefficient thermistor arranged in parallel with a resistor.
- PTC positive temperature coefficient
- an additional resistance is arranged in parallel, which will partly take over, when the resistance of the thermistor has increased due to the temperature rise.
- the current in the high voltage coil is low and the temperature of the transformer is low, such that the resistance of the PTC thermistor is small or even not relevant. So, the current in the high voltage coil during normal operation will flow through the PTC thermistor leaving the additional resistance out of use.
- An additional advantage of having means for increasing the resistance arranged in the primary, high voltage, coil is that these means can be arranged per voltage measuring transformer. So, a three phase setup is not required and the invention can also be applied to a single phase voltage measuring transformer.
- a varistor is provided for protection of the thermistor.
- the resistance of a varistor decreases abruptly upon increased voltage. So, when the voltage due to ferro-resonance increases to such a high level, that otherwise the PTC thermistor would be damaged, the varistor will shunt the thermistor and prevent damage to the thermistor.
- Yet another embodiment of the voltage measuring transformer according to the invention comprises at least two thermistors being in heat conducting contact with each other.
- the at least two thermistors are arranged on a heat conducting frame.
- This heat conducting frame could be integrated in the frame of the voltage measuring transformer.
- the means for increasing the resistance comprise at least a bipolar transistor.
- a PTC thermistor instead of a PTC thermistor it is also possible use a bipolar transistor like an Insulated-gate bipolar transistor (IGBT) or Gate turn-off thyristor (GTO).
- IGBT Insulated-gate bipolar transistor
- GTO Gate turn-off thyristor
- the figure shows a schematic view of an embodiment of the voltage measuring transformer according to the invention.
- the figure shows a three phase setup for transforming a high voltage three phase current L1, L2, L3 into a low voltage three phase current l1, l2,l3.
- Each voltage measuring transformer 1 has a high voltage primary coil 2 and a low voltage secondary coil 3 (shown schematically in the figure).
- each high voltage primary coil 2 is grounded while the other side of the primary coil is connected to one of the phases L1, L2, L3 of the high voltage power supply.
- means 4, 5 for increasing the resistance upon the occurrence of ferro-resonance are arranged in series with the primary, high voltage, coil 2 of the voltage measuring transformer 1. These means 4, 5 are arranged on the high voltage side of the transformer 1, but can also be arranged on the grounded side.
- the means for increasing the resistance have a positive temperature coefficient thermistor 4 and a conventional resistor 5 arranged in parallel.
- the current through the primary coil 2 will be low, such that the temperature remains low.
- the resistance of the PTC thermistor 4 will be small, such that the current goes through the PTC thermistor 4.
- the resistance of the resistor 5 will be selected high, such that in normal operation, virtually no current will flow through the resistor 5.
- the conventional resistor 5 will ensure that the current through the thermistor 4 will be kept within limits, as with increasing resistance of the thermistor 4, part of the current will go through the conventional resistor 5.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformers For Measuring Instruments (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP12152587.7A EP2620959A1 (fr) | 2012-01-26 | 2012-01-26 | Transformateur de mesure de tension |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP12152587.7A EP2620959A1 (fr) | 2012-01-26 | 2012-01-26 | Transformateur de mesure de tension |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2620959A1 true EP2620959A1 (fr) | 2013-07-31 |
Family
ID=45507617
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP12152587.7A Withdrawn EP2620959A1 (fr) | 2012-01-26 | 2012-01-26 | Transformateur de mesure de tension |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP2620959A1 (fr) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106067737A (zh) * | 2016-02-25 | 2016-11-02 | 中国科学院等离子体物理研究所 | 一种自取能供电方法 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB928923A (en) * | 1959-11-25 | 1963-06-19 | Micafil Ag | Circuit arrangement for preventing sawtooth oscillations in capacitive potential transformers |
GB1569188A (en) * | 1975-11-20 | 1980-06-11 | Transmicro Scandinavia Ab | Electrical transformer system |
JPS5642323A (en) * | 1979-09-14 | 1981-04-20 | Toshiba Corp | Capacitor type potential transformer |
EP1727257A1 (fr) | 2005-05-25 | 2006-11-29 | ABB Sp.zo.o. | Circuit de protéction pour transformateurs de tension |
CN102024554A (zh) * | 2009-09-21 | 2011-04-20 | 芮骏 | 三相电力电网电磁式电压互感器消谐保护器 |
-
2012
- 2012-01-26 EP EP12152587.7A patent/EP2620959A1/fr not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB928923A (en) * | 1959-11-25 | 1963-06-19 | Micafil Ag | Circuit arrangement for preventing sawtooth oscillations in capacitive potential transformers |
GB1569188A (en) * | 1975-11-20 | 1980-06-11 | Transmicro Scandinavia Ab | Electrical transformer system |
JPS5642323A (en) * | 1979-09-14 | 1981-04-20 | Toshiba Corp | Capacitor type potential transformer |
EP1727257A1 (fr) | 2005-05-25 | 2006-11-29 | ABB Sp.zo.o. | Circuit de protéction pour transformateurs de tension |
CN102024554A (zh) * | 2009-09-21 | 2011-04-20 | 芮骏 | 三相电力电网电磁式电压互感器消谐保护器 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106067737A (zh) * | 2016-02-25 | 2016-11-02 | 中国科学院等离子体物理研究所 | 一种自取能供电方法 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
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AX | Request for extension of the european patent |
Extension state: BA ME |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20140201 |